Receptive aphasia

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Receptive_aphasia

Receptive aphasia
Other names	Wernicke's aphasia, fluent aphasia, sensory aphasia
Broca's area and Wernicke's area
Specialty	Neurology

Wernicke's aphasia, also known as receptive aphasia, sensory aphasia or posterior aphasia, is a type of aphasia in which individuals have difficulty understanding written and spoken language. Patients with Wernicke's aphasia demonstrate fluent speech, which is characterized by typical speech rate, intact syntactic abilities and effortless speech output. Writing often reflects speech in that it tends to lack content or meaning. In most cases, motor deficits (i.e. hemiparesis) do not occur in individuals with Wernicke's aphasia. Therefore, they may produce a large amount of speech without much meaning. Individuals with Wernicke's aphasia are typically unaware of their errors in speech and do not realize their speech may lack meaning. They typically remain unaware of even their most profound language deficits.

Like many acquired language disorders, Wernicke's aphasia can be experienced in many different ways and to many different degrees. Patients diagnosed with Wernicke's aphasia can show severe language comprehension deficits; however, this is dependent on the severity and extent of the lesion. Severity levels may range from being unable to understand even the simplest spoken and/or written information to missing minor details of a conversation. Many diagnosed with Wernicke's aphasia have difficulty with repetition in words and sentences and/or working memory.

Wernicke's aphasia was named after German physician Carl Wernicke, who is credited with discovering the area of the brain responsible for language comprehension (Wernicke's area).

Signs and symptoms

The following are common symptoms seen in patients with Wernicke's aphasia:

Impaired comprehension: deficits in understanding (receptive) written and spoken language. This is because Wernicke's area is responsible for assigning meaning to the language that is heard, so if it is damaged, the brain cannot comprehend the information that is being received.

Poor word retrieval: ability to retrieve target words is impaired. This is also referred to as anomia.

Fluent speech: individuals with Wernicke's aphasia do not have difficulty with producing connected speech that flows. Although the connection of the words may be appropriate, the words they are using may not belong together or make sense (see Production of jargon below). 

Production of jargon: speech that lacks content, consists of typical intonation, and is structurally intact. Jargon can consist of a string of neologisms, as well as a combination of real words that do not make sense together in context. May include word salads. 

Awareness: Individuals with Wernicke's aphasia are often not aware of their incorrect productions, which would further explain why they do not correct themselves when they produce jargon, paraphasias, or neologisms.

Paraphasias:

• Phonemic (literal) paraphasias: involves the substitution, addition, or rearrangement of sounds so that an error can be defined as sounding like the target word. Often, half of the word is still intact which allows for easy comparison to the appropriate, original word.
  • Ex: "bap" for "map"
• Semantic (verbal) paraphasias: saying a word that is related to the target word in meaning or category; frequently observed in Wernicke's aphasia.
  • Ex: "jet" for "airplane" or "knife" for "fork"

Neologisms: nonwords that have no relation to the target word.

• Ex: "dorflur" for "shoe"

Circumlocution: talking around the target word.

• Ex: "uhhh it's white...it's flat...you write on it…" (when referencing paper)

Press of speech: run-on speech.

• If a clinician asks, "what do you do at a supermarket?" And the individual responds with "Well, the supermarket is a place. It is a place with a lot of food. My favorite food is italian food. At a supermarket, I buy different kinds of food. There are carts and baskets. Supermarkets have lots of customers, and workers…."

Lack of hemiparesis: typically, no motor deficits are seen with a localized lesion in Wernicke's area.

Reduced retention span: reduced ability to retain information for extended periods of time.

Impairments in reading and writing: impairments can be seen in both reading and writing with differing severity levels.

How to differentiate from other types of aphasia

• Expressive aphasia (non-fluent Broca's aphasia): individuals have great difficulty forming complete sentences with generally only basic content words (leaving out words like "is" and "the").
• Global aphasia: individuals have extreme difficulties with both expressive (producing language) and receptive (understanding language).
• Anomic aphasia: the biggest hallmark is an individuals poor word finding abilities; their speech is fluent and appropriate, but full of circumlocutions (evident in both writing and speech).
• Conduction aphasia: individual can comprehend what is being said and is fluent in spontaneous speech, but they cannot repeat what is being said to them.

Causes

The most common cause of Wernicke's aphasia is stroke. Strokes may occur when blood flow to the brain is completely interrupted or severely reduced. This has a direct effect on the amount of oxygen and nutrients being able to supply the brain, which causes brain cells to die within minutes. The primary classifications of stroke are hemorrhagic (ruptured blood vessel), or ischemic (blood clot reduces or completely stops blood flow). Two of the most common types of hemorrhagic stroke are subarachnoid hemorrhage and intracerebral hemorrhage. Subarachnoid hemorrhage is when an artery near the surface of the brain bursts causing blood to leak into the space between the brain and skull. Meanwhile intracerebral hemorrhage occurs when a blood vessel inside the brain bursts, causing spillage into surrounding brain tissue. Three main causes of these hemorrhagic strokes are hypertension (uncontrolled high blood pressure), aneurisms (weak spots in blood vessel walls), and arteriovenous malformations (rupture of abnormal tangle of thin-walled blood vessels). As previously noted the other major classification for a stroke is an ischemic stroke. The ischemic strokes, which are the most common form of stroke, are further broken down and can be classified as embolic or thrombotic. Embolic strokes occur when a blood clot forms away from the brain, typically in the heart. A small portion of this clot breaks away and travels through the blood vessels until eventually reaching a small enough vessel in the brain that it can no longer pass through, causing a blockage. Thrombotic strokes on the other hand are due to the formation of a blood clot directly formed in one of the arteries that supply the brain. In general, stroke is the number one leading cause of disability worldwide.,

"The middle cerebral arteries supply blood to the cortical areas involved in speech, language and swallowing. The left middle cerebral artery provides Broca's area, Wernicke's area, Heschl's gyrus, and the angular gyrus with blood". Therefore, in patients with Wernicke's aphasia, there is typically an occlusion to the left middle cerebral artery. 

As a result of the occlusion in the left middle cerebral artery, Wernicke's aphasia is most commonly caused by a lesion in the posterior superior temporal gyrus (Wernicke's area). This area is posterior to the primary auditory cortex (PAC) which is responsible for decoding individual speech sounds. Wernicke's primary responsibility is to assign meaning to these speech sounds. The extent of the lesion will determine the severity of the patients deficits related to language. Damage to the surrounding areas (perisylvian region) may also result in Wernicke's aphasia symptoms due to variation in individual neuroanatomical structure and any co-occurring damage in adjacent areas of the brain.

Diagnosis

"Aphasia is usually first recognized by the physician who treats the person for his or her brain injury. Most individuals will undergo a magnetic resonance imaging (MRI) or computed tomography (CT) scan to confirm the presence of a brain injury and to identify its precise location." In circumstances where a person is showing possible signs of aphasia, the physician will refer him or her to a speech-language pathologist (SLP) for a comprehensive speech and language evaluation. SLPs will examine the individual's ability to express him or herself through speech, understand language in written and spoken forms, write independently, and perform socially.

The American Speech, Language, Hearing Association (ASHA) states a comprehensive assessment should be conducted in order to analyze the patient's communication functioning on multiple levels; as well as the effect of possible communication deficits on activities of daily living. Typical components of an aphasia assessment include: case history, self report, oral-motor examination, language skills, identification of environmental and personal factors, and the assessment results. A comprehensive aphasia assessment includes both formal and informal measures.

Formal assessments:

• Boston Diagnostic Aphasia Examination (BDAE): diagnoses the presence and type of aphasia, focusing on location of lesion and the underlying linguistic processes. 
• Western Aphasia Battery - Revised (WAB): determines the presence, severity, and type of aphasia; and can also determine baseline abilities of patient.
• Communication Activities of Daily Living - Second Edition (CADL-2): measures functional communication abilities; focuses on reading, writing, social interactions, and varying levels of communication.
• Revised Token Test (RTT): assess receptive language and auditory comprehension; focuses on patient's ability to follow directions.

Informal assessments: 

Informal assessments aide in the diagnosis of patients with suspected aphasia.

• Conversational speech and language sample
• Family interview
• Case history or medical chart review
• Behavioral observations

Diagnostic information should be scored and analyzed appropriately. Treatment plans and individual goals should be developed based on diagnostic information, as well as patient and caregiver needs, desires, and priorities.

Treatment

According to Bates et al. (2005), "the primary goal of rehabilitation is to prevent complications, minimize impairments, and maximize function". The topics of intensity and timing of intervention are widely debated across various fields. Results are contradictory: some studies indicate better outcomes with early intervention, while other studies indicate starting therapy too early may be detrimental to the patient's recovery. Recent research suggests, that therapy be functional and focus on communication goals that are appropriate for the patient's individual lifestyle.

Specific treatment considerations for working with individuals with Wernicke's aphasia (or those who exhibit deficits in auditory comprehension) include using familiar materials, using shorter and slower utterances when speaking, giving direct instructions, and using repetition as needed.

Neuroplasticity: Role in Recovery 

Neuroplasticity is defined as the brain's ability to reorganize itself, lay new pathways, and rearrange existing ones, as a result of experience. Neuronal changes after damage to the brain such as collateral sprouting, increased activation of the homologous areas, and map extension demonstrate the brain's neuroplastic abilities. According to Thomson, "Portions of the right hemisphere, extended left brain sites, or both have been shown to be recruited to perform language functions after brain damage. All of the neuronal changes recruit areas not originally or directly responsible for large portions of linguistic processing. Principles of neuroplasticity have been proven effective in neurorehabilitation after damage to the brain. These principles include: incorporating multiple modalities into treatment to create stronger neural connections, using stimuli that evoke positive emotion, linking concepts with simultaneous and related presentations, and finding the appropriate intensity and duration of treatment for each individual patient.

Auditory comprehension treatment

Auditory comprehension is a primary focus in treatment for Wernicke's aphasia, as it is the main deficit related to this diagnosis. Therapy activities may include:

• Single-word comprehension: A common treatment method used to support single-word comprehension skills is known as a pointing drill. Through this method, clinicians lay out a variety of images in front of a patient. The patient is asked to point to the image that corresponds to the word provided by the clinician.
• Understanding spoken sentences: "Treatment to improve comprehension of spoken sentences typically consists of drills in which patients answer questions, follow directions or verify the meaning of sentences".
• Understanding conversation: An effective treatment method to support comprehension of discourse includes providing a patient with a conversational sample and asking him or her questions about that sample. Individuals with less severe deficits in auditory comprehension may also be able to retell aspects of the conversation.

Word retrieval

Anomia is consistently seen in aphasia, so many treatment techniques aim to help patients with word finding problems. One example of a semantic approach is referred to as semantic feature analyses. The process includes naming the target object shown in the picture and producing words that are semantically related to the target. Through production of semantically similar features, participants develop more skilled in naming stimuli due to the increase in lexical activation.

Restorative therapy approach

Neuroplasticity is a central component to restorative therapy to compensate for brain damage. This approach is especially useful in Wernicke's aphasia patients that have suffered from a stroke to the left brain hemisphere. 

Schuell's stimulation approach is a main method in traditional aphasia therapy that follows principles to retrieve function in the auditory modality of language and influence surrounding regions through stimulation. The guidelines to have the most effective stimulation are as follows: Auditory stimulation of language should be intensive and always present when other language modalities are stimulated. 

• The stimulus should be presented at a difficulty level equal to or just below the patient’s ability.
• Sensory stimulation must be present and repeated throughout the treatment.
• Each stimulus applied should produce a response; if there is no response more stimulation cues should be provided.
• Response to stimuli should be maximized to create more opportunities for success and feedback for the speech-language pathologist.
• The feedback of the speech-language pathologist should promote further success and patient and encouragement.
• Therapy should follow an intensive and systemic method to create success by progressing in difficulty.
• Therapies should be varied and build off of mastered therapy tasks. 

Schuell’s stimulation utilizes stimulation through therapy tasks beginning at a simplified task and progressing to become more difficult including:

Point to tasks. During these tasks the patient is directed to point to an object or multiple objects. As the skill is learned the level of complexity increases by increasing the number of objects the patient must point to. 

• Simple: "Point to the book."

• Complex: "Point to the book and then to the ceiling after touching your ear."

Following directions with objects. During these tasks the patient is instructed to follow the instruction of manually following directions that increase in complexity as the skill is learned. 

* Simple: "Pick up the book." 

* Complex: "Pick up the book and put it down on the bench after I move the cup." 

Yes or no questions - This task requires the patient to respond to various yes or no questions that can range from simple to complex.

Paraphrasing and retelling - This task requires the patient to read a paragraph and, afterwords, paraphrase it aloud. This is the most complex of Schuell’s stimulation tasks because it requires comprehension, recall, and communication.

Social approach to treatment

The social approach involves a collaborative effort on behalf of patients and clinicians to determine goals and outcomes for therapy that could improve the patient's quality of life. A conversational approach is thought to provide opportunities for development and the use of strategies to overcome barriers to communication. The main goals of this treatment method are to improve the patient's conversational confidence and skills in natural contexts using conversational coaching, supported conversations, and partner training.

• Conversational coaching involves patients with aphasia and their speech language pathologists, who serve as a "coach" discussing strategies to approach various communicative scenarios. The "coach" will help the patient develop a script for a scenario (such as ordering food at a restaurant), and help the patient practice and perform the scenario in and out of the clinic while evaluating the outcome.
• Supported conversation also involves using a communicative partner who supports the patient's learning by providing contextual cues, slowing their own rate of speech, and increasing their message's redundancy to promote the patient's comprehension.

Additionally, it is important to include the families of patients with aphasia in treatment programs. Clinicians can teach family members how to support one another, and how to adjust their speaking patterns to facilitate their loved one's treatment and rehabilitation.

Prognosis

Prognosis is strongly dependent on the location and extent of the lesion (damage) to the brain. Many personal factors also influence how a person will recover, which include age, previous medical history, level of education, gender, and motivation. All of these factors influence the brain's ability to adapt to change, restore previous skills, and learn new skills. It is important to remember that all the presentations of Receptive Aphasia may vary. The presentation of symptoms and prognosis are both dependent on personal components related to the individual's neural organization before the stroke, the extent of the damage, and the influence of environmental and behavioral factors after the damage occurs. The quicker a diagnosis of a stroke is made by a medical team, the more positive the patient's recovery may be. A medical team will work to control the signs and symptoms of the stroke and rehabilitation therapy will begin to manage and recover lost skills. The rehabilitation team may consist of a certified speech-language pathologist, physical therapist, occupational therapist, and the family or caregivers. The length of therapy will be different for everyone, but research suggests that intense therapy over a short amount of time can improve outcomes of speech and language therapy for patients with aphasia. Research is not suggesting the only way therapy should be administered, but gives insight on how therapy affects the patient's prognosis.

Expressive aphasia

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Expressive_aphasia 

 

Expressive aphasia
Other names	Broca's aphasia, non-fluent aphasia, agrammatic aphasia
Broca's area and Wernicke's area
Specialty	Neurology

Expressive aphasia, also known as Broca's aphasia, is a type of aphasia characterized by partial loss of the ability to produce language (spoken, manual, or written), although comprehension generally remains intact. A person with expressive aphasia will exhibit effortful speech. Speech generally includes important content words but leaves out function words that have only grammatical significance and not real-world meaning, such as prepositions and articles. This is known as "telegraphic speech". The person's intended message may still be understood, but their sentence will not be grammatically correct. In very severe forms of expressive aphasia, a person may only speak using single word utterances. Typically, comprehension is mildly to moderately impaired in expressive aphasia due to difficulty understanding complex grammar.

It is caused by acquired damage to the anterior regions of the brain, such as Broca's area. It is one subset of a larger family of disorders known collectively as aphasia. Expressive aphasia contrasts with receptive aphasia, in which patients are able to speak in grammatical sentences that lack semantic significance and generally also have trouble with comprehension. Expressive aphasia differs from dysarthria, which is typified by a patient's inability to properly move the muscles of the tongue and mouth to produce speech. Expressive aphasia also differs from apraxia of speech, which is a motor disorder characterized by an inability to create and sequence motor plans for speech.

Signs and symptoms

Broca's (expressive) aphasia is a type of non-fluent aphasia in which an individual's speech is halting and effortful. Misarticulations or distortions of consonants and vowels, namely phonetic dissolution, are common. Individuals with expressive aphasia may only produce single words, or words in groups of two or three. Long pauses between words are common and multi-syllabic words may be produced one syllable at a time with pauses between each syllable. The prosody of a person with Broca's aphasia is compromised by shortened length of utterances and the presence of self-repairs and disfluencies. Intonation and stress patterns are also deficient.

For example, in the following passage, a patient with Broca's aphasia is trying to explain how he came to the hospital for dental surgery:

Yes... ah... Monday... er... Dad and Peter H... (his own name), and Dad.... er... hospital... and ah... Wednesday... Wednesday, nine o'clock... and oh... Thursday... ten o'clock, ah doctors... two... an' doctors... and er... teeth... yah.

The speech of a person with expressive aphasia contains mostly content words such as nouns, verbs, and some adjectives. However, function words like conjunctions, articles, and prepositions are rarely used except for “and” which is prevalent in the speech of most patients with aphasia. The omission of function words makes the person's speech agrammatic. A communication partner of a person with aphasia may say that the person's speech sounds telegraphic due to poor sentence construction and disjointed words. For example, a person with expressive aphasia might say "Smart... university... smart... good... good..."

Self-monitoring is typically well preserved in patients with Broca's aphasia. They are usually aware of their communication deficits, and are more prone to depression and outbursts from frustration than are patients with other forms of aphasia.

In general, word comprehension is preserved, allowing patients to have functional receptive language skills. Individuals with Broca's aphasia understand most of the everyday conversation around them, but higher-level deficits in receptive language can occur. Because comprehension is substantially impaired for more complex sentences, it is better to use simple language when speaking with an individual with expressive aphasia. This is exemplified by the difficulty to understand phrases or sentences with unusual structure. A typical patient with Broca's aphasia will misinterpret "the man is bitten by the dog" by switching the subject and object to “the dog is bitten by the man.”

Typically, people with expressive aphasia can understand speech and read better than they can produce speech and write. The person's writing will resemble their speech and will be effortful, lacking cohesion, and containing mostly content words. Letters will likely be formed clumsily and distorted and some may even be omitted. Although listening and reading are generally intact, subtle deficits in both reading and listening comprehension are almost always present during assessment of aphasia.

Because Broca's area is anterior to the primary motor cortex, which is responsible for movement of the face, hands, and arms, a lesion affecting Broca's areas may also result in hemiparesis (weakness of both limbs on the same side of the body) or hemiplegia (paralysis of both limbs on the same side of the body). The brain is wired contralaterally, which means the limbs on right side of the body are controlled by the left hemisphere and vice versa. Therefore, when Broca's area or surrounding areas in the left hemisphere are damaged, hemiplegia or hemiparesis often occurs on the right side of the body in individuals with Broca's aphasia.

Severity of expressive aphasia varies among patients. Some people may only have mild deficits and detecting problems with their language may be difficult. In the most extreme cases, patients may be able to produce only a single word. Even in such cases, over-learned and rote-learned speech patterns may be retained for instance, some patients can count from one to ten, but cannot produce the same numbers in novel conversation.

Manual language and aphasia

In deaf patients who use manual language (such as American Sign Language), damage to the left hemisphere of the brain leads to disruptions in their signing ability. Paraphasic errors similar to spoken language have been observed; whereas in spoken language a phonemic substitution would occur (e.g. "tagle" instead of "table"), in ASL case studies errors in movement, hand position, and morphology have been noted. Agrammatism, or the lack of grammatical morphemes in sentence production, has also been observed in lifelong users of ASL who have left hemisphere damage. The lack of syntactic accuracy shows that the errors in signing are not due to damage to the motor cortex, but rather are a manifestation of the damage to the language-producing area of the brain. Similar symptoms have been seen in a patient with left hemisphere damage whose first language was British Sign Language, further showing that damage to the left hemisphere primarily hinders linguistic ability, not motor ability. In contrast, patients who have damage to non-linguistic areas on the left hemisphere have been shown to be fluent in signing, but are unable to comprehend written language.

Overlap with receptive aphasia

In addition to difficulty expressing oneself, individuals with expressive aphasia are also noted to commonly have trouble with comprehension in certain linguistic areas. This agrammatism overlaps with receptive aphasia, but can be seen in patients who have expressive aphasia without being diagnosed as having receptive aphasia. The most well-noted of these are object-relative clauses, object Wh- questions, and topicalized structures (placing the topic at the beginning of the sentence). These three concepts all share phrasal movement, which can cause words to lose their thematic roles when they change order in the sentence. This is often not an issue for people without agrammatic aphasias, but many people with aphasia rely heavily on word order to understand roles that words play within the sentence.

Causes

More common

• Stroke or brain anoxia.
• Brain tumor
• Brain trauma

Less common

• Autoimmune disease
• Paraneoplastic syndrome
• Micrometastasis
• neurodegenerative disorders
• Certain infections (e.g., Bartonella henselae)
• Metabolic disease (e.g., hyperosmolar hyperglycemic state)

Common causes

The most common cause of expressive aphasia is stroke. A stroke is caused by hypoperfusion (lack of oxygen) to an area of the brain, which is commonly caused by thrombosis or embolism. Some form of aphasia occurs in 34 to 38% of stroke patients. Expressive aphasia occurs in approximately 12% of new cases of aphasia caused by stroke.

In most cases, expressive aphasia is caused by a stroke in Broca's area or the surrounding vicinity. Broca's area is in the lower part of the premotor cortex in the language dominant hemisphere and is responsible for planning motor speech movements. However, cases of expressive aphasia have been seen in patients with strokes in other areas of the brain. Patients with classic symptoms of expressive aphasia in general have more acute brain lesions, whereas patients with larger, widespread lesions exhibit a variety of symptoms that may be classified as global aphasia or left unclassified.

Expressive aphasia can also be caused by trauma to the brain, tumor, cerebral hemorrhage and by extradural abscess.

Understanding lateralization of brain function is important for understanding which areas of the brain cause expressive aphasia when damaged. In the past, it has been believed that the area for language production differs between left and right-handed individuals. If this were true, damage to the homologous region of Broca's area in the right hemisphere should cause aphasia in a left-handed individual. More recent studies have shown that even left-handed individuals typically have language functions only in the left hemisphere. However, left-handed individuals are more likely to have a dominance of language in the right hemisphere.

Uncommon causes

Less common causes of expressive aphasia include primary autoimmune phenomenon and autoimmune phenomenon that are secondary to cancer (as a paraneoplastic syndrome) have been listed as the primary hypothesis for several cases of aphasia, especially when presenting with other psychiatric disturbances and focal neurological deficits. Many case reports exist describing paraneoplastic aphasia, and the reports that are specific tend to describe expressive aphasia. Although most cases attempt to exclude micrometastasis, it is likely that some cases of paraneoplastic aphasia are actually extremely small metastasis to the vocal motor regions.

Neurodegenerative disorders may present with aphasia. Alzheimer's disease may present with either fluent aphasia or expressive aphasia. There are case reports of Creutzfeldt-Jakob disease presenting with expressive aphasia.

Diagnosis

Expressive aphasia is classified as non-fluent aphasia, as opposed to fluent aphasia. Diagnosis is done on a case-by-case basis, as lesions often affect the surrounding cortex and deficits are highly variable among patients with aphasia.

A physician is typically the first person to recognize aphasia in a patient who is being treated for damage to the brain. Routine processes for determining the presence and location of lesion in the brain include magnetic resonance imaging (MRI) and computed tomography (CT) scans. The physician will complete a brief assessment of the patient's ability to understand and produce language. For further diagnostic testing, the physician will refer the patient to a speech-language pathologist, who will complete a comprehensive evaluation.

In order to diagnose a patient who is suffering from Broca's aphasia, there are certain commonly used tests and procedures. The Western Aphasia Battery (WAB) classifies individuals based on their scores on the subtests; spontaneous speech, auditory comprehension, repetition, and naming. The Boston Diagnostic Aphasia Examination (BDAE) can inform users what specific type of aphasia they may have, infer the location of lesion, and assess current language abilities. The Porch Index of Communication Ability (PICA) can predict potential recovery outcomes of the patients with aphasia. Quality of life measurement is also an important assessment tool. Tests such as the Assessment for Living with Aphasia (ALA) and the Satisfaction with Life Scale (SWLS) allow for therapists to target skills that are important and meaningful for the individual.

In addition to formal assessments, patient and family interviews are valid and important sources of information. The patient's previous hobbies, interests, personality, and occupation are all factors that will not only impact therapy but may motivate them throughout the recovery process. Patient interviews and observations allow professionals to learn the priorities of the patient and family and determine what the patient hopes to regain in therapy. Observations of the patient may also be beneficial to determine where to begin treatment. The current behaviors and interactions of the patient will provide the therapist with more insight about the client and their individual needs. Other information about the patient can be retrieved from medical records, patient referrals from physicians, and the nursing staff.

In non-speaking patients who use manual languages, diagnosis is often based on interviews from the patient's acquaintances, noting the differences in sign production pre- and post-damage to the brain. Many of these patients will also begin to rely on non-linguistic gestures to communicate, rather than signing since their language production is hindered.

Treatment

Currently, there is no standard treatment for expressive aphasia. Most aphasia treatment is individualized based on a patient's condition and needs as assessed by a speech language pathologist. Patients go through a period of spontaneous recovery following brain injury in which they regain a great deal of language function.

In the months following injury or stroke, most patients receive traditional treatment for a few hours per day. Among other exercises, patients practice the repetition of words and phrases. Mechanisms are also taught in traditional treatment to compensate for lost language function such as drawing and using phrases that are easier to pronounce.

Emphasis is placed on establishing a basis for communication with family and caregivers in everyday life. Treatment is individualized based on the patient's own priorities, along with the family's input.

A patient may have the option of individual or group treatment. Although less common, group treatment has been shown to have advantageous outcomes. Some types of group treatments include family counseling, maintenance groups, support groups and treatment groups.

Melodic intonation therapy

Melodic intonation therapy was inspired by the observation that individuals with non-fluent aphasia sometimes can sing words or phrases that they normally cannot speak. "Melodic Intonation Therapy was begun as an attempt to use the intact melodic/prosodic processing skills of the right hemisphere in those with aphasia to help cue retrieval words and expressive language." It is believed that this is because singing capabilities are stored in the right hemisphere of the brain, which is likely to remain unaffected after a stroke in the left hemisphere. However, recent evidence demonstrates that the capability of individuals with aphasia to sing entire pieces of text may actually result from rhythmic features and the familiarity with the lyrics.

The goal of Melodic Intonation Therapy is to utilize singing to access the language-capable regions in the right hemisphere and use these regions to compensate for lost function in the left hemisphere. The natural musical component of speech was used to engage the patients' ability to produce phrases. A clinical study revealed that singing and rhythmic speech may be similarly effective in the treatment of non-fluent aphasia and apraxia of speech. Moreover, evidence from randomized controlled trials is still needed to confirm that Melodic Intonation Therapy is suitable to improve propositional utterances and speech intelligibility in individuals with (chronic) non-fluent aphasia and apraxia of speech.

Melodic Intonation Therapy appears to work particularly well in patients who have had a unilateral, left hemisphere stroke, show poor articulation, are non-fluent or have severely restricted speech output, have moderately preserved auditory comprehension, and show good motivation. MIT therapy on average lasts for 1.5 hours per day for five days per week. At the lowest level of therapy, simple words and phrases (such as "water" and "I love you") are broken down into a series of high- and low-pitch syllables. With increased treatment, longer phrases are taught and less support is provided by the therapist. Patients are taught to say phrases using the natural melodic component of speaking and continuous voicing is emphasized. The patient is also instructed to use the left hand to tap the syllables of the phrase while the phrases are spoken. Tapping is assumed to trigger the rhythmic component of speaking to utilize the right hemisphere.

FMRI studies have shown that Melodic Intonation Therapy (MIT) uses both sides of the brain to recover lost function, as opposed to traditional therapies that utilize only the left hemisphere. In MIT, individuals with small lesions in the left hemisphere seem to recover by activation of the left hemisphere perilesional cortex. Meanwhile, individuals with larger left-hemisphere lesions show a recruitment of the use of language-capable regions in the right hemisphere. The interpretation of these results is still a matter of debate. For example, it remains unclear whether changes in neural activity in the right hemisphere result from singing or from the intensive use of common phrases, such as "thank you", "how are you?" or "I am fine." This type of phrases falls into the category of formulaic language and is known to be supported by neural networks of the intact right hemisphere.

A pilot study reported positive results when comparing the efficacy of a modified form of MIT to no treatment in people with nonfluent aphasia with damage to their left-brain. A randomized controlled trial was conducted and the study reported benefits of utilizing modified MIT treatment early in the recovery phase for people with nonfluent aphasia.

Melodic Intonation Therapy is used by music therapists, board-certified professionals that use music as a therapeutic tool to effect certain non-musical outcomes in their patients. Speech language pathologists can also use this therapy for individuals who have had a left hemisphere stroke and non-fluent aphasias such as Broca's or even apraxia of speech.

Constraint-induced therapy

Constraint-induced aphasia therapy (CIAT) is based on similar principles as constraint-induced movement therapy developed by Dr. Edward Taub at the University of Alabama at Birmingham. Constraint-induced movement therapy is based on the idea that a person with an impairment (physical or communicative) develops a "learned nonuse" by compensating for the lost function with other means such as using an unaffected limb by a paralyzed individual or drawing by a patient with aphasia. In constraint-induced movement therapy, the alternative limb is constrained with a glove or sling and the patient is forced to use the affected limb. In constraint-induced aphasia therapy the interaction is guided by communicative need in a language game context, picture cards, barriers making it impossible to see other players' cards, and other materials, so that patients are encouraged ("constrained") to use the remaining verbal abilities to succeed in the communication game.

Two important principles of constraint-induced aphasia therapy are that treatment is very intense, with sessions lasting for up to 6 hours over the course of 10 days and that language is used in a communication context in which it is closely linked to (nonverbal) actions. These principles are motivated by neuroscience insights about learning at the level of nerve cells (synaptic plasticity) and the coupling between cortical systems for language and action in the human brain. Constraint-induced therapy contrasts sharply with traditional therapy by the strong belief that mechanisms to compensate for lost language function, such as gesturing or writing, should not be used unless absolutely necessary, even in everyday life.

It is believed that CIAT works by the mechanism of increased neuroplasticity. By constraining an individual to use only speech, it is believed that the brain is more likely to reestablish old neural pathways and recruit new neural pathways to compensate for lost function. 

The strongest results of CIAT have been seen in patients with chronic aphasia (lasting over 6 months). Studies of CIAT have confirmed that further improvement is possible even after a patient has reached a "plateau" period of recovery. It has also been proven that the benefits of CIAT are retained long term. However, improvements only seem to be made while a patient is undergoing intense therapy. Recent work has investigated combining constraint-induced aphasia therapy with drug treatment, which led to an amplification of therapy benefits.

Medication

In addition to active speech therapy, pharmaceuticals have also been considered as a useful treatment for expressive aphasia. This area of study is relatively new and much research continues to be conducted. 

The following drugs have been suggested for use in treating aphasia and their efficacy has been studied in control studies.

• Bromocriptine – acts on Catecholamine Systems
• Piracetam – mechanism not fully understood, but most likely interacts with cholinergic and glutamatergic receptors, among others
• Cholinergic drugs (Donepezil, Aniracetam, Bifemelane) – acts on acetylcholine systems
• Dopaminergic psychostimulants: (Dexamphetamine, Methylphenidate)

The most effect has been shown by piracetam and amphetamine, which may increase cerebral plasticity and result in an increased capability to improve language function. It has been seen that piracetam is most effective when treatment is begun immediately following stroke. When used in chronic cases it has been much less efficient.

Bromocriptine has been shown by some studies to increase verbal fluency and word retrieval with therapy than with just therapy alone. Furthermore, its use seems to be restricted to non-fluent aphasia.

Donepezil has shown a potential for helping chronic aphasia.

No study has established irrefutable evidence that any drug is an effective treatment for aphasia therapy. Furthermore, no study has shown any drug to be specific for language recovery. Comparison between the recovery of language function and other motor function using any drug has shown that improvement is due to a global increase plasticity of neural networks.

Transcranial magnetic stimulation

In transcranial magnetic stimulation (TMS), magnetic fields are used to create electrical currents in specified cortical regions. The procedure is a painless and noninvasive method of stimulating the cortex. TMS works by suppressing the inhibition process in certain areas of the brain. By suppressing the inhibition of neurons by external factors, the targeted area of the brain may be reactivated and thereby recruited to compensate for lost function. Research has shown that patients can demonstrate increased object naming ability with regular transcranial magnetic stimulation than patients not receiving TMS. Furthermore, research suggests this improvement is sustained upon the completion of TMS therapy. However, some patients fail to show any significant improvement from TMS which indicates the need for further research of this treatment.

Treatment of underlying forms

Described as the linguistic approach to the treatment of expressive aphasia, treatment begins by emphasizing and educating patients on the thematic roles of words within sentences. Sentences that are usually problematic will be reworded into active-voiced, declarative phrasings of their non-canonical counterparts. The simpler sentence phrasings are then transformed into variations that are more difficult to interpret. For example, many individuals who have expressive aphasia struggle with Wh- sentences. "What" and "who" questions are problematic sentences that this treatment method attempts to improve, and they are also two interrogative particles that are strongly related to each other because they reorder arguments from the declarative counterparts. For instance, therapists have used sentences like, "Who is the boy helping?" and "What is the boy fixing?" because both verbs are transitive- they require two arguments in the form of a subject and a direct object, but not necessarily an indirect object. In addition, certain question particles are linked together based on how the reworded sentence is formed. Training "who" sentences increased the generalizations of non-trained "who" sentences as well as untrained "what" sentences, and vice versa. Likewise, "where" and "when" question types are very closely linked. "What" and "who" questions alter placement of arguments, and "where" and "when" sentences move adjunct phrases. Training is in the style of: "The man parked the car in the driveway. What did the man park in the driveway?" Sentence training goes on in this manner for more domains, such as clefts and sentence voice.

Results: Patients’ use of sentence types used in the TUF treatment will improve, subjects will generalize sentences of similar category to those used for treatment in TUF, and results are applied to real-world conversations with others. Generalization of sentence types used can be improved when the treatment progresses in the order of more complex sentences to more elementary sentences. Treatment has been shown to affect on-line (real-time) processing of trained sentences and these results can be tracked using fMRI mappings. Training of Wh- sentences has led improvements in three main areas of discourse for aphasics: increased average length of utterances, higher proportions of grammatical sentences, and larger ratios of numbers of verbs to nouns produced. Patients also showed improvements in verb argument structure productions and assigned thematic roles to words in utterances with more accuracy. In terms of on-line sentence processing, patients having undergone this treatment discriminate between anomalous and non-anomalous sentences with more accuracy than control groups and are closer to levels of normalcy than patients not having participated in this treatment.

Mechanisms of recovery

Mechanisms for recovery differ from patient to patient. Some mechanisms for recovery occur spontaneously after damage to the brain, whereas others are caused by the effects of language therapy. FMRI studies have shown that recovery can be partially attributed to the activation of tissue around the damaged area and the recruitment of new neurons in these areas to compensate for the lost function. Recovery may also be caused in very acute lesions by a return of blood flow and function to damaged tissue that has not died around an injured area. It has been stated by some researchers that the recruitment and recovery of neurons in the left hemisphere opposed to the recruitment of similar neurons in the right hemisphere is superior for long-term recovery and continued rehabilitation. It is thought that, because the right hemisphere is not intended for full language function, using the right hemisphere as a mechanism of recovery is effectively a "dead-end" and can lead only to partial recovery.

It has been proven that, among all types of therapies, one of the most important factors and best predictors for a successful outcome is the intensity of the therapy. By comparing the length and intensity of various methods of therapies, it was proven that intensity is a better predictor of recovery than the method of therapy used.

Prognosis

In most individuals with expressive aphasia, the majority of recovery is seen within the first year following a stroke or injury. The majority of this improvement is seen in the first four weeks in therapy following a stroke and slows thereafter. However, this timeline will vary depending upon the type of stroke experienced by the patient. Patients who experienced an ischemic stroke may recover in the days and weeks following the stroke, and then experience a plateau and gradual slowing of recovery. On the contrary, patients who experienced a hemorrhagic stroke experience a slower recovery in the first 4–8 weeks, followed by a faster recovery which eventually stabilizes.^[57]

Numerous factors impact the recovery process and outcomes. Site and extent of lesion greatly impacts recovery. Other factors that may affect prognosis are age, education, gender, and motivation. Occupation, handedness, personality, and emotional state may also be associated with recovery outcomes.

Studies have also found that prognosis of expressive aphasia correlates strongly with the initial severity of impairment. However, it has been seen that continued recovery is possible years after a stroke with effective treatment. Timing and intensity of treatment is another factor that impacts outcomes. Research suggests that even in later stages of recovery, intervention is effective at improving function, as well as, preventing loss of function.

Unlike receptive aphasia, patients with expressive aphasia are aware of their errors in language production. This may further motivate a person with expressive aphasia to progress in treatment, which would affect treatment outcomes. On the other hand, awareness of impairment may lead to higher levels of frustration, depression, anxiety, or social withdrawal, which have been proven to negatively affect a person's chance of recovery.

History

Expressive aphasia was first identified by the French neurologist Paul Broca. By examining the brains of deceased individuals having acquired expressive aphasia in life, he concluded that language ability is localized in the ventroposterior region of the frontal lobe. One of the most important aspects of Paul Broca's discovery was the observation that the loss of proper speech in expressive aphasia is due to the brain's loss of ability to produce language, as opposed to the mouth's loss of ability to produce words.

The discoveries of Paul Broca were made during the same period of time as the German Neurologist Carl Wernicke, who was also studying brains of aphasiacs post-mortem and identified the region now known as Wernicke's area. Discoveries of both men contributed to the concept of localization, which states that specific brain functions are all localized to a specific area of the brain. While both men made significant contributions to the field of aphasia, it was Carl Wernicke who realized the difference between patients with aphasia that could not produce language and those that could not comprehend language (the essential difference between expressive and receptive aphasia).

Psycholinguistics

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Psycholinguistics 

Psycholinguistics or psychology of language is the study of the interrelation between linguistic factors and psychological aspects.

The field is concerned with psychological and neurobiological factors that enable humans to acquire, use, comprehend and produce language. The discipline is mainly concerned with the mechanisms in which languages are processed and represented in the mind and brain.

Modern research makes use of biology, neuroscience, cognitive science, linguistics, and information science to study how the mind-brain processes language, and less so the known processes of social sciences, human development, communication theories and infant development, among others. There are a number of sub-disciplines with non-invasive techniques for studying the neurological workings of the brain; for example, neurolinguistics has become a field in its own right. Initial forays into psycholinguistics were found in philosophical and educational fields, due mainly to their location in departments other than applied sciences (e.g., cohesive data on how the human brain functioned).

Psycholinguistics is concerned with the cognitive faculties and processes that are necessary in order for grammatical forms of language to be produced from a mental grammar and the lexicon. It is also concerned with the perception of these constructions by a listener. Developmental psycholinguistics, as a branch of psycholinguistics, concerns itself with the child's ability to learn language.

Areas of study

Psycholinguistics is an interdisciplinary field. Hence, it is studied by researchers from a variety of different backgrounds, such as psychology, cognitive science, linguistics, speech and language pathology, and discourse analysis. Psycholinguists study many different topics, but these topics can generally be divided into answering the following questions: (1) how do children acquire language (language acquisition)?; (2) how do people comprehend language (language comprehension)?; (3) how do people produce language (language production)?; and (4) how do people who already know one language acquire another one(second language acquisition)?

Subdivisions in psycholinguistics are also made based on the different components that make up human language. 

Linguistics-related areas:

• Phonetics and phonology are concerned with the study of speech sounds. Within psycholinguistics, research focuses on how the brain processes and understands these sounds.
• Morphology is the study of word structures, especially the relationships between related words (such as dog and dogs) and the formation of words based on rules (such as plural formation).
• Syntax is the study of the patterns which dictate how words are combined to form sentences.
• Semantics deals with the meaning of words and sentences. Where syntax is concerned with the formal structure of sentences, semantics deals with the actual meaning of sentences.
• Pragmatics is concerned with the role of context in the interpretation of meaning.

A researcher interested in language comprehension may study word recognition during reading to examine the processes involved in the extraction of orthographic, morphological, phonological, and semantic information from patterns in printed text. A researcher interested in language production might study how words are prepared to be spoken starting from the conceptual or semantic level (this concerns connotation, and possibly can be examined through the conceptual framework concerned with the semantic differential). Developmental psycholinguists study infants' and children's ability to learn and process language.

History of psycholinguistics

Language acquisition and innateness

Psycholinguistics, in seeking to understand the properties of language acquisition has roots in debates regarding innate vs acquired behaviors (both in biology and psychology). For some time the concept of an innate trait, was something that was not present in the psychology of the individual^[4] . However, with the redefining of innateness as time progressed, behaviors considered innate could once again be analyzed as behaviors that interacted with the psychological aspect of an individual. After the diminished popularity of the behaviorist model, ethology became once again a leading train of thought within psychology, and by these means language, as an innate behavior within humans, could be examined once more in the scope of psychology.

Origin of designation

Even though psycholinguistics originated in terms of methodology, and in theoretical framework from a time before the end of the nineteenth century it was called only "Psychology of Language". The nomenclature for the science as Psycholinguistics did not begin to come about until 1936 when Jacob Kantor, a prominent Psychologist of the time, used the term ‘Psycholinguistic’ as a description within the book An Objective Psychology of Grammar. The term only came to relevant usage, however in 1946 when the student of Kantor, Nicholas Pronko published an article by the title Psycholinguistics: A Review. Pronko's desire was to unify the myriad of theoretical approaches within the realm of Psycholinguistics under a single name. It was used for the first time to talk about an interdisciplinary science "that could be coherent" as well as in the title of Psycholinguistics: A Survey of Theory and Research Problems, a 1954 book by Charles E. Osgood and Thomas A. Sebeok.

Theories

In this section, some influential theories are discussed for each of the fundamental questions listed in the section above.

Language acquisition

There are essentially two schools of thought as to how children acquire or learn language, and there is still much debate as to which theory is the correct one. The first theory states that all language must be learned by the child. The second view states that the abstract system of language cannot be learned, but that humans possess an innate language faculty, or an access to what has been called universal grammar. The view that language must be learned was especially popular before 1960 and is well represented by the mentalistic theories of Jean Piaget and the empiricist Rudolf Carnap. Likewise, the school of psychology known as behaviorism (see Verbal Behavior (1957) by B.F. Skinner) puts forth the point of view that language is a behavior shaped by conditioned response, hence it is learned.

The innatist perspective began with Noam Chomsky's highly critical review of Skinner's book in 1959.^[9] This review helped to start what has been termed "the cognitive revolution" in psychology. Chomsky posited humans possess a special, innate ability for language and that complex syntactic features, such as recursion, are "hard-wired" in the brain. These abilities are thought to be beyond the grasp of the most intelligent and social non-humans. According to Chomsky, children acquiring a language have a vast search space to explore among all possible human grammars, yet at the time there was no evidence that children receive sufficient input to learn all the rules of their language (see poverty of the stimulus). Hence, there must be some other innate mechanism that endows a language ability to humans. Such a language faculty is, according to the innateness hypothesis, what defines human language and makes it different from even the most sophisticated forms of animal communication.

The field of linguistics and psycholinguistics since then has been defined by reactions to Chomsky, pro and con. The pro view still holds that the human ability to use language (specifically the ability to use recursion) is qualitatively different from any sort of animal ability. This ability may have resulted from a favorable mutation or from an adaptation of skills evolved for other purposes. The view that language can be learned has had a recent resurgence inspired by emergentism. This view challenges the "innate" view as scientifically unfalsifiable; that is to say, it can't be tested. With the amount of computer power increasing since the 1980s, researchers have been able to simulate language acquisition using neural network models. These models provide evidence that there may, in fact, be sufficient information contained in the input to learn language, even syntax. If this is true, then an innate mechanism is no longer necessary to explain language acquisition.

Language comprehension

The structures and uses of language are related to the formation of ontological insights. Some see this system as "structured cooperation between language-users" using "conceptual difference""semantic deference" in order to exchange meaning and knowledge and give meaning to language, examining and describing "semantic processes bound by a ‘stopping’ constraint which are not cases of ordinary deferring. Deferring is normally done for a reason, and a rational person is always disposed to defer if there is good reason.

The theory of the Semantic differential supposes universal distinctions such as factors of "Typicality" (that included scales such as "regular-rare", "typical-exclusive"), "Reality" ("imaginary-real", "evident-fantastic", "abstract-concrete"), as well as factors of "Complexity" ("complex-simple", "unlimited-limited", "mysterious-usual"), "Improvement" or "Organization" ("regular-spasmodic", "constant-changeable", "organized-disorganized", "precise-indefinite"), Stimulation ("interesting-boring", "trivial-new"), calling it " in the measurement of attitudes."

Reading

One question in the realm of language comprehension is how people understand sentences as they read (also known as sentence processing). Experimental research has spawned a number of theories about the architecture and mechanisms of sentence comprehension. Typically these theories are concerned with what types of information contained in the sentence the reader can use to build meaning, and at what point in reading does that information become available to the reader. Issues such as "modular" versus "interactive" processing have been theoretical divides in the field.

A modular view of sentence processing assumes that the stages involved in reading a sentence function independently in separate modules. These modules have limited interaction with one another. For example, one influential theory of sentence processing, the garden-path theory, states that syntactic analysis takes place first. Under this theory as the reader is reading a sentence, he or she creates the simplest structure possible in order to minimize effort and cognitive load. This is done without any input from semantic analysis or context-dependent information. Hence, in the sentence "The evidence examined by the lawyer turned out to be unreliable," by the time the reader gets to the word "examined" he or she has committed to a reading of the sentence in which the evidence is examining something because it is the simplest parse. This commitment is made despite the fact that it results in an implausible situation; we know from experience that evidence can rarely if ever examine something. Under this "syntax first" theory, semantic information is processed at a later stage. It is only later that the reader will recognize that he or she needs to revise the initial parse into one in which "the evidence" is being examined. In this example, readers typically recognize their misparse by the time they reach "by the lawyer" and must go back and re-parse the sentence. This reanalysis is costly and contributes to slower reading times.

In contrast to a modular account, an interactive theory of sentence processing, such as a constraint-based lexical approach assumes that all available information contained within a sentence can be processed at any time. Under an interactive account, for example, the semantics of a sentence (such as plausibility) can come into play early on in order to help determine the structure of a sentence. Hence, in the sentence above, the reader would be able to make use of plausibility information in order to assume that "the evidence" is being examined instead of doing the examining. There are data to support both modular and interactive accounts; which account is the correct one is still up for debate.

When reading, saccades can cause the mind to skip over words because it doesn’t see them as important to the sentence, and the mind completely leaves it from the sentence or it replaces it with the wrong word. This can be seen in ‘Paris in the the Spring’. This is a common psychological test, where the mind will often skip the second ‘the’, especially when there is a line break in between the two.

Language production

Language production concerns how people produce language, either in written or spoken form, in a way that conveys meanings comprehensible to others. One of the most effective ways to explain the way people represent meanings using rule-governed languages is by observing and analyzing instances of speech errors. They include speech dysfluencies like false starts, repetition, reformulation and constant pauses in between words or sentences; also, slips of tongue, like blendings, substitutions, exchanges (e.g. Spoonerism), and various pronunciation errors. These speech errors yield significant implication on language production, in that they reflect that:

1. Speech is planned in advance: speech errors like substitution and exchanges show that one does not plan their entire sentence before they speak. Rather, their language faculty is constantly tapped during the speech production process. This is accounted for by the limitation of the working memory. In particular, errors involving exchanges imply that one plans ahead in their sentence but only about significant ideas (e.g. the words that constitute the core meaning) and only to a certain extent of the sentence.
2. Lexicon is organized semantically and phonologically: substitution and pronunciation errors show that lexicon is organized not only by its meaning, but also its form.
3. Morphologically complex words are assembled: errors involving blending within a word reflect that there seems to be a rule governing the construction of words in production (and also likely in mental lexicon). In other words, speakers generate the morphologically complex words by merging morphemes rather than retrieving them as chunks.

It is useful to differentiate between three separate phases of production: conceptualization "(determining what to say), formulation (translating the intention to say something into linguistic form), and execution (the detailed articulatory planning and articulation itself)." Most psycholinguistic research has largely concerned itself with the study for formulation because the phase of conceptualization largely remains an elusive and mysterious period of development.

For models of speech production, see Psycholinguistics/Models of Speech Production.

Methodologies

Behavioral tasks

Many of the experiments conducted in psycholinguistics, especially earlier on, are behavioral in nature. In these types of studies, subjects are presented with linguistic stimuli and asked to perform an action. For example, they may be asked to make a judgment about a word (lexical decision), reproduce the stimulus, or name a visually presented word aloud. Reaction times to respond to the stimuli (usually on the order of milliseconds) and proportion of correct responses are the most often employed measures of performance in behavioral tasks. Such experiments often take advantage of priming effects, whereby a "priming" word or phrase appearing in the experiment can speed up the lexical decision for a related "target" word later.

As an example of how behavioral methods can be used in psycholinguistics research, Fischler (1977) investigated word encoding using the lexical decision task. He asked participants to make decisions about whether two strings of letters were English words. Sometimes the strings would be actual English words requiring a "yes" response, and other times they would be nonwords requiring a "no" response. A subset of the licit words were related semantically (e.g., cat-dog) while others were unrelated (e.g., bread-stem). Fischler found that related word pairs were responded to faster when compared to unrelated word pairs. This facilitation suggests that semantic relatedness can facilitate word encoding.

Eye-movements

Recently, eye tracking has been used to study online language processing. Beginning with Rayner (1978) the importance and informativity of eye-movements during reading was established. Later, Tanenhaus et al. (1995) used the visual-world paradigm to study the cognitive processes related to spoken language. Assuming that eye movements are closely linked to the current focus of attention, language processing can be studied by monitoring eye movements while a subject is presented auditorily with linguistic input.

Language production errors

The analysis of systematic errors in speech, writing and typing of language as it is produced can provide evidence of the process which has generated it. Errors of speech, in particular, grant insight into how the mind processes language production while a speaker is in the midst of an utterance. Speech errors tend to occur in the lexical, morpheme, and phoneme encoding steps of language production, as seen by the ways errors can manifest. The types of speech errors, and some examples, are:

• Substitutions (phoneme and lexical) – replacing a sound with an unrelated sound, or a word with an antonym, and saying "verbal outfit" instead of "verbal output", or "He rode his bike tomorrow" instead of "...yesterday", respectively,
• Blends – mixing two synonyms together and saying "my stummy hurts" in place of either "stomach" or "tummy",
• Exchanges (phoneme [a.k.a. Spoonerisms] and morpheme) – swapping two onset sounds or two root words, and saying "You hissed my mystery lectures" instead of "You missed my history lectures", or "They're Turking talkish" instead of "They're talking Turkish", respectively,
• Morpheme shifts – moving a function morpheme such as "-ly" or "-ed" to a different word and saying "easy enoughly" instead of "easily enough",
• Perseveration – continuing to start a word with a sound that was in the utterance previously and saying "John gave the goy a ball" instead of "John gave the boy a ball", and
• Anticipation – replacing a sound with one that is coming up later in the utterance and saying "She drank a cot cup of tea" instead of "She drank a hot cup of tea."

Speech errors will usually occur in the stages that involve lexical, morpheme, or phoneme encoding, and usually not the first step of semantic encoding. This can be credited to how a speaker is still conjuring the idea of what to say, and unless he changes his mind, can not be mistaken in what he wanted to say.

Neuroimaging

Until the recent advent of non-invasive medical techniques, brain surgery was the preferred way for language researchers to discover how language works in the brain. For example, severing the corpus callosum (the bundle of nerves that connects the two hemispheres of the brain) was at one time a treatment for some forms of epilepsy. Researchers could then study the ways in which the comprehension and production of language were affected by such drastic surgery. Where an illness made brain surgery necessary, language researchers had an opportunity to pursue their research. 

Newer, non-invasive techniques now include brain imaging by positron emission tomography (PET); functional magnetic resonance imaging (fMRI); event-related potentials (ERPs) in electroencephalography (EEG) and magnetoencephalography (MEG); and transcranial magnetic stimulation (TMS). Brain imaging techniques vary in their spatial and temporal resolutions (fMRI has a resolution of a few thousand neurons per pixel, and ERP has millisecond accuracy). Each type of methodology presents a set of advantages and disadvantages for studying a particular problem in psycholinguistics.

Computational modeling

Computational modelling, such as the DRC model of reading and word recognition proposed by Max Coltheart and colleagues, is another methodology and refers to the practice of setting up cognitive models in the form of executable computer programs. Such programs are useful because they require theorists to be explicit in their hypotheses and because they can be used to generate accurate predictions for theoretical models that are so complex that they render discursive analysis unreliable. Other examples of computational modelling is McClelland and Elman's TRACE model of speech perception and Franklin Chang's Dual-Path model of sentence production.

Issues and areas of research

Psycholinguistics is concerned with the nature of the computations and processes that the brain undergoes to comprehend and produce language. For example, the cohort model seeks to describe how words are retrieved from the mental lexicon when an individual hears or sees linguistic input.

Recent research using new non-invasive imaging techniques seeks to shed light on just where certain language processes occur in the brain. 

There are a number of unanswered questions in psycholinguistics, such as whether the human ability to use syntax is based on innate mental structures or emerges from interaction with other humans, and whether some animals can be taught the syntax of human language. 

Two other major subfields of psycholinguistics investigate first language acquisition, the process by which infants acquire language, and second language acquisition. In addition, it is much more difficult for adults to acquire second languages than it is for infants to learn their first language (bilingual infants are able to learn both of their native languages easily). Thus, sensitive periods may exist during which language can be learned readily. A great deal of research in psycholinguistics focuses on how this ability develops and diminishes over time. It also seems to be the case that the more languages one knows, the easier it is to learn more.

The field of aphasiology deals with language deficits that arise because of brain damage. Studies in aphasiology can both offer advances in therapy for individuals suffering from aphasia, and further insight into how the brain processes language. 

A 2016 empirical study showed that personal associations are mutually inter-related and that the concepts of self and world are internally connected via direct and mediated dependences, which reflects the structuring of perception and understanding of self and world in people's minds and discusses its implications for psycholinguistics.