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Saturday, July 29, 2023

Parallel port

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Parallel_port
Parallel port
A DB-25 connector often used for a parallel printer port on IBM PC compatible computers, with the printer icon.
Type Point-to-point
Production history
Designer Centronics, IBM
Designed 1970–1981
Manufacturer Centronics, Dataproducts, Intel, IBM, Compaq, Nortel, etc
Superseded by USB (1996)
General specifications
Length 2.3 cm (0.91 in)
Hot pluggable Usually not
External Yes
Cable Usually up to 25 wires including ground; optionally shielded
Pins 8 data, 4 output control, 5 input control, 8 ground
Connector DB-25, DB25F, "Centronics" 36-pin Amphenol, DC-37, others
Electrical
Signal 0 to +5.0 volt DC
Earth Dedicated pins
Max. voltage 5 volts DC
Data
Data signal Parallel
Width Variable
Bitrate PP: 150 kB/s,
EPP: 2 MB/s
ECP: 2.5 MB/s
Max. devices 2
Protocol Application dependent
Pinout
IBM PC-compatible parallel port pinout
Micro ribbon 36-pin female, such as on printers and on some computers, particularly industrial equipment and early (pre-1980s) personal computers.
Mini-Centronics 36-pin male connector (top) with Micro ribbon 36-pin male Centronics connector (bottom)
The Apple II Parallel Printer Port connected to the printer via a folded ribbon cable; one end connected to the connector at the top of the card, and the other end had a 36-pin Centronics connector.

In computing, a parallel port is a type of interface found on early computers (personal and otherwise) for connecting peripherals. The name refers to the way the data is sent; parallel ports send multiple bits of data at once (parallel communication), as opposed to serial communication, in which bits are sent one at a time. To do this, parallel ports require multiple data lines in their cables and port connectors and tend to be larger than contemporary serial ports, which only require one data line.

There are many types of parallel ports, but the term has become most closely associated with the printer port or Centronics port found on most personal computers from the 1970s through the 2000s. It was an industry de facto standard for many years, and was finally standardized as IEEE 1284 in the late 1990s, which defined the Enhanced Parallel Port (EPP) and Extended Capability Port (ECP) bi-directional versions. Today, the parallel port interface is virtually non-existent in new computers because of the rise of Universal Serial Bus (USB) devices, along with network printing using Ethernet and Wi-Fi connected printers.

The parallel port interface was originally known as the Parallel Printer Adapter on IBM PC-compatible computers. It was primarily designed to operate printers that used IBM's eight-bit extended ASCII character set to print text, but could also be used to adapt other peripherals. Graphical printers, along with a host of other devices, have been designed to communicate with the system.

History

Centronics

An Wang, Robert Howard and Prentice Robinson began development of a low-cost printer at Centronics, a subsidiary of Wang Laboratories that produced specialty computer terminals. The printer used the dot matrix printing principle, with a print head consisting of a vertical row of seven metal pins connected to solenoids. When power was applied to the solenoids, the pin was pushed forward to strike the paper and leave a dot. To make a complete character glyph, the print head would receive power to specified pins to create a single vertical pattern, then the print head would move to the right by a small amount, and the process repeated. On their original design, a typical glyph was printed as a matrix seven high and five wide, while the "A" models used a print head with 9 pins and formed glyphs that were 9 by 7.

This left the problem of sending the ASCII data to the printer. While a serial port does so with the minimum of pins and wires, it requires the device to buffer up the data as it arrives bit by bit and turn it back into multi-bit values. A parallel port makes this simpler; the entire ASCII value is presented on the pins in complete form. In addition to the eight data pins, the system also needed various control pins as well as electrical grounds. Wang happened to have a surplus stock of 20,000 Amphenol 36-pin micro ribbon connectors that were originally used for one of their early calculators. The interface only required 21 of these pins, the rest were grounded or not connected. The connector has become so closely associated with Centronics that it is now popularly known as the "Centronics connector".

The Centronics Model 101 printer, featuring this connector, was released in 1970. The host sent ASCII characters to the printer using seven of eight data pins, pulling them high to +5V to represent a 1. When the data was ready, the host pulled the STROBE pin low, to 0 V. The printer responded by pulling the BUSY line high, printing the character, and then returning BUSY to low again. The host could then send another character. Control characters in the data caused other actions, like the CR or EOF. The host could also have the printer automatically start a new line by pulling the AUTOFEED line high, and keeping it there. The host had to carefully watch the BUSY line to ensure it did not feed data to the printer too rapidly, especially given variable-time operations like a paper feed.

The printer side of the interface quickly became an industry de facto standard, but manufacturers used various connectors on the system side, so a variety of cables were required. For example, NCR used the 36-pin micro ribbon connector on both ends of the connection, early VAX systems used a DC-37 connector, Texas Instruments used a 25-pin card edge connector and Data General used a 50-pin micro ribbon connector. When IBM implemented the parallel interface on the IBM PC, they used the DB-25F connector at the PC-end of the interface, creating the now familiar parallel cable with a DB25M at one end and a 36-pin micro ribbon connector at the other.

In theory, the Centronics port could transfer data as rapidly as 75,000 characters per second. This was far faster than the printer, which averaged about 160 characters per second, meaning the port spent much of its time idle. The performance was defined by how rapidly the host could respond to the printer's BUSY signal asking for more data. To improve performance, printers began incorporating buffers so the host could send them data more rapidly, in bursts. This not only reduced (or eliminated) delays due to latency waiting for the next character to arrive from the host, but also freed the host to perform other operations without causing a loss of performance. Performance was further improved by using the buffer to store several lines and then printing in both directions, eliminating the delay while the print head returned to the left side of the page. Such changes more than doubled the performance of an otherwise unchanged printer, as was the case on Centronics models like the 102 and 308.

IBM

IBM released the IBM Personal Computer in 1981 and included a variant of the Centronics interface— only IBM logo printers (rebranded from Epson) could be used with the IBM PC. IBM standardized the parallel cable with a DB25F connector on the PC side and the 36-pin Centronics connector on the printer side. Vendors soon released printers compatible with both standard Centronics and the IBM implementation.

The original IBM parallel printer adapter for the IBM PC of 1981 was designed to support limited bidirectionality, with 8 lines of data output and 4 lines of data input. This allowed the port to be used for other purposes, not just output to a printer. This was accomplished by allowing the data lines to be written to by devices on either end of the cable, which required the ports on the host to be bidirectional. This feature saw little use, and was removed in later revisions of the hardware. Years later, in 1987, IBM reintroduced the bidirectional interface with its IBM PS/2 series, where it could be enabled or disabled for compatibility with applications hardwired not to expect a printer port to be bidirectional.

Bi-Tronics

As the printer market expanded, new types of printing mechanisms appeared. These often supported new features and error conditions that could not be represented on the existing port's relatively few status pins. While the IBM solution could support this, it was not trivial to implement and was not at that time being supported. This led to the Bi-Tronics system, introduced by HP on their LaserJet 4Si in April 1993. This used four existing status pins, ERROR, SELECT, PE and BUSY to represent a nibble, using two transfers to send an 8-bit value. Bi-Tronics mode, now known as nibble mode, was indicated by the host pulling the SELECT line high, and data was transferred when the host toggles the AUTOFEED low. Other changes in the handshaking protocols improved performance, reaching 400,000 cps to the printer, and about 50,000 cps back to the host. A major advantage of the Bi-Tronics system is that it can be driven entirely in software in the host, and uses otherwise unmodified hardware - all the pins used for data transfer back to the host were already printer-to-host lines.

EPP and ECP

The introduction of new devices like scanners and multi-function printers demanded much more performance than either the Bi-Tronics or IBM style backchannels could handle. Two other standards have become more popular for these purposes. The Enhanced Parallel Port (EPP), originally defined by Zenith Electronics, is similar to IBM's byte mode in concept, but changes details of the handshaking to allow up to 2 MB/s. The Extended Capability Port (ECP) is essentially an entirely new port in the same physical housing that also adds direct memory access based on ISA and run-length encoding to compress the data, which is especially useful when transferring simple images like faxes or black-and-white scanned images. ECP offers performance up to 2.5 MB/s in both directions.

All of these enhancements are collected as part of the IEEE 1284 standard. The first release in 1994 included original Centronics mode ("compatibility mode"), nibble and byte modes, as well as a change to the handshaking that was already widely used; the original Centronics implementation called for the BUSY lead to toggle with each change on any line of data (busy-by-line), whereas IEEE 1284 calls for BUSY to toggle with each received character (busy-by-character). This reduces the number of BUSY toggles and the resulting interruptions on both sides. A 1997 update standardized the printer status codes. In 2000, the EPP and ECP modes were moved into the standard, as well as several connector and cable styles, and a method for daisy chaining up to eight devices from a single port.

Some host systems or print servers may use a strobe signal with a relatively low voltage output or a fast toggle. Any of these issues might cause no or intermittent printing, missing or repeated characters or garbage printing. Some printer models may have a switch or setting to set busy by character; others may require a handshake adapter.

Dataproducts

Dataproducts introduced a very different implementation of the parallel interface for their printers. It used a DC-37 connector on the host side and a 50 pin connector on the printer side—either a DD-50 (sometimes incorrectly referred to as a "DB50") or the block shaped M-50 connector; the M-50 was also referred to as Winchester. Dataproducts parallel was available in a short-line for connections up to 50 feet (15 m) and a long-line version using differential signaling for connections to 500 feet (150 m). The Dataproducts interface was found on many mainframe systems up through the 1990s, and many printer manufacturers offered the Dataproducts interface as an option.

A wide variety of devices were eventually designed to operate on a parallel port. Most devices were uni-directional (one-way) devices, only meant to respond to information sent from the PC. However, some devices such as Zip drives were able to operate in bi-directional mode. Printers also eventually took up the bi-directional system, allowing various status report information to be sent.

Historical uses

HP C4381A CD-Writer Plus 7200 Series, showing parallel ports to connect between a printer and the computer.

Before the advent of USB, the parallel interface was adapted to access a number of peripheral devices other than printers. One early use of the parallel port was for dongles used as hardware keys which were supplied with application software as a form of software copy protection. Other uses included optical disc drives such as CD readers and writers, Zip drives, scanners, tape drives, external modems, gamepads, and joysticks. Some of the earliest portable MP3 players required a parallel port connection for transferring songs to the device. Adapters were available to run SCSI devices via parallel. Other devices such as EPROM programmers and hardware controllers could be connected via the parallel port.

Interfaces

Most PC-compatible systems in the 1980s and 1990s had one to three ports, with communication interfaces defined like this:

  • Logical parallel port 1: I/O port 0x3BC, IRQ 7 (usually in monochrome graphics adapters)
  • Logical parallel port 2: I/O port 0x378, IRQ 7 (dedicated IO cards or using a controller built into the mainboard)
  • Logical parallel port 3: I/O port 0x278, IRQ 5 (dedicated IO cards or using a controller built into the mainboard)

If no printer port is present at 0x3BC, the second port in the row (0x378) becomes logical parallel port 1 and 0x278 becomes logical parallel port 2 for the BIOS. Sometimes, printer ports are jumpered to share an interrupt despite having their own IO addresses (i.e. only one can be used interrupt-driven at a time). In some cases, the BIOS supports a fourth printer port as well, but the base address for it differs significantly between vendors. Since the reserved entry for a fourth logical printer port in the BIOS Data Area (BDA) is shared with other uses on PS/2 machines and with S3 compatible graphics cards, it typically requires special drivers in most environments. Under DR-DOS 7.02 the BIOS port assignments can be changed and overridden using the LPT1, LPT2, LPT3 (and optionally LPT4) CONFIG.SYS directives.

Access

DOS-based systems make the logical parallel ports detected by the BIOS available under device names such as LPT1, LPT2 or LPT3 (corresponding with logical parallel port 1, 2, and 3, respectively). These names derive from terms like Line Print Terminal, Local Print Terminal (both abbreviated as LPT), or Line Printer. A similar naming convention was used on ITS, DEC systems, as well as in CP/M and 86-DOS (LST).

In DOS, the parallel printers could be accessed directly on the command line. For example, the command "TYPE C:\AUTOEXEC.BAT > LPT1:" would redirect the contents of the AUTOEXEC.BAT file to the printer port. A PRN device was also available as an alias for LPT1. Some operating systems (like Multiuser DOS) allow to change this fixed assignment by different means. Some DOS versions use resident driver extensions provided by MODE, or users can change the mapping internally via a CONFIG.SYS PRN=n directive (as under DR-DOS 7.02 and higher). DR-DOS 7.02 also provides optional built-in support for LPT4 if the underlying BIOS supports it.

PRN, along with CON, AUX and a few others are invalid file and directory names in DOS and Windows, even in Windows XP. There is even an MS-DOS device in path name vulnerability in Windows 95 and 98, which causes the computer to crash if the user types "C:\CON\CON", "C:\PRN\PRN" or "C:\AUX\AUX" in the Windows Explorer address bar. Microsoft has released a patch to fix this bug, but newly installed Windows 95 and 98 operating systems will still have the bug.

A special "PRINT" command also existed to achieve the same effect. Microsoft Windows still refers to the ports in this manner in many cases, though this is often fairly hidden.

In SCO UNIX and Linux, the first parallel port is available via the filesystem as /dev/lp0. Linux IDE devices can use a paride (parallel port IDE) driver.

Notable consumer products

Accton Etherpocket-SP parallel port ethernet adaptor (circa 1990, DOS drivers). Supports both coax and 10 Base-T. Supplementary power is drawn from a PS/2 port passthrough cable.

Current use

For consumers, USB and computer networks have replaced the parallel printer port, for connections both to printers and to other devices.

Many manufacturers of personal computers and laptops consider parallel to be a legacy port and no longer include the parallel interface. Smaller machines have less room for large parallel port connectors. USB-to-parallel adapters are available that can make parallel-only printers work with USB-only systems. There are PCI (and PCI-express) cards that provide parallel ports. There are also some print servers that provide an interface to parallel ports through a network. USB-to-EPP chips can also allow other non-printer devices to continue to work on modern computers without a parallel port.

For electronics hobbyists the parallel port is still often the easiest way to connect to an external circuit board. It is faster than the other common legacy port (serial port), requires no serial-to-parallel converter, and requires far less interface logic and software than a USB target interface. However, Microsoft operating systems later than Windows 95/98 prevent user programs from directly writing to or reading from the LPT without additional software (kernel extensions).

Current CNC Milling Machines also often make use of the parallel port to directly control the machine's motors and attachments.

IBM PC implementation

Port addresses

Traditionally IBM PC systems have allocated their first three parallel ports according to the configuration in the table below (if all three printer ports exist).

PORT NO Interrupt # Starting I/O Ending I/O
#1 IRQ 7 0x3BC 0x3BF
#2 IRQ 7 0x378 0x37F
#3 IRQ 5 0x278 0x27F

If there is an unused slot, the port addresses of the others are moved up. (For example, if a port at 0x3BC does not exist, the port at 0x378 will then become the first logical parallel port.) The base address 0x3BC is typically supported by printer ports on MDA and Hercules display adapters, whereas printer ports provided by the mainboard chipset or add-on cards rarely allow to be configured to this base address. Therefore, in absence of a monochrome display adapter, a common assignment for the first logical parallel port (and therefore also for the corresponding LPT1 DOS device driver) today is 0x378, even though the default is still 0x3BC (and would be selected by the BIOS if it detects a printer port at this address). The IRQ lines are typically configurable in the hardware as well. Assigning the same interrupt to more than one printer port should be avoided and will typically cause one of the corresponding ports to work in polled mode only. The port addresses assigned to slot can be determined by reading the BIOS Data Area (BDA) at 0000h:0408h.

Bit-to-pin mapping for the Standard Parallel Port (SPP):

Address
MSB





LSB

Bit: 7 6 5 4 3 2 1 0
Base (Data port) Pin: 9 8 7 6 5 4 3 2
Base+1 (Status port) Pin: ~11 10 12 13 15


Base+2 (Control port) Pin:



~17 16 ~14 ~1

~ indicates a hardware inversion of the bit.

Program interface

In versions of Windows that did not use the Windows NT kernel (as well as DOS and some other operating systems), programs could access the parallel port with simple outportb() and inportb() subroutine commands. In operating systems such as Windows NT and Unix (NetBSD, FreeBSD, Solaris, 386BSD, etc.), the microprocessor is operated in a different security ring, and access to the parallel port is prohibited, unless using the required driver. This improves security and arbitration of device contention. On Linux, inb() and outb() can be used when a process is run as root and an ioperm() command is used to allow access to its base address; alternatively, ppdev allows shared access and can be used from userspace if the appropriate permissions are set.

The cross-platform library for parallel port access, libieee1284, also is available on many Linux distributions and provides an abstract interface to the parallel ports of the system. Access is handled in an open-claim-release-close sequence, which allows for concurrent access in userspace.

Pinouts

The older parallel printer ports had an 8-bit data bus and four pins for control output (Strobe, Linefeed, Initialize, and Select In), and five more for control input (ACK, Busy, Select, Error, and Paper Out). Its data transfer speed is at 150 kB/s.

The newer EPPs (Enhanced Parallel Ports) have an 8-bit data bus, and the same control pins as the normal parallel printer port. Newer ports reach speeds of up to 2 MB/s.

Pinouts for parallel port connectors are:

Pinouts for parallel port connectors.
Pin No (DB25) Pin No (36 pin) Signal name Direction Register - bit Inverted
1 1 Strobe In/out Control-0 Yes
2 2 Data0 Out Data-0 No
3 3 Data1 Out Data-1 No
4 4 Data2 Out Data-2 No
5 5 Data3 Out Data-3 No
6 6 Data4 Out Data-4 No
7 7 Data5 Out Data-5 No
8 8 Data6 Out Data-6 No
9 9 Data7 Out Data-7 No
10 10 Ack In Status-6 No
11 11 Busy In Status-7 Yes
12 12 Paper-Out In Status-5 No
13 13 Select In Status-4 No
14 14 Linefeed In/out Control-1 Yes
15 32 Error In Status-3 No
16 31 Reset In/out Control-2 No
17 36 Select-Printer In/out Control-3 Yes
18-25 19-30,33,17,16 Ground - - -

Inverted lines are true on logic low. If they are not inverted, then logic high is true.

Pin 25 on the DB25 connector might not be connected to ground on modern computers.

School bullying

From Wikipedia, the free encyclopedia
Bullying, one form of which is depicted in this staged photograph, is detrimental to students' well-being and development.

School bullying, like bullying outside the school context, refers to one or more perpetrators who have greater physical strength or more social power than their victim and who repeatedly act aggressively toward their victim. Bullying can be verbal or physical. Bullying, with its ongoing character, is distinct from one-off types of peer conflict. Different types of school bullying include ongoing physical, emotional, and/or verbal aggression. Cyberbullying and sexual bullying are also types of bullying. Bullying even exists in higher education. There are warning signs that suggest that a child is being bullied, a child is acting as a bully, or a child has witnessed bullying at school.

The cost of school violence is significant across many nations but there are educational leaders who have had success in reducing school bullying by implementing certain strategies. Some strategies used to reduce or prevent school bullying include educating the students about bullying, restricting of recording devices in the classroom, employing security technology, and hiring school safety officers. How schools respond to bullying, however, varies widely. Effects on the victims of school bullying include feelings of depression, anxiety, anger, stress, helplessness, and reduced school performance Empirical research by Sameer Hinduja and Justin Patchin involving a national sample of US youth have found that some victims of school bullying have attempted to commit suicide.

This behavior is not a one-off episode; it must be repetitive and habitual to be considered bullying. Students who are LGBT, have parents of lower educational levels, are thought to be provocative, are perceived to be vulnerable, or are atypical or considered outsiders are at higher risk of being victimized by bullies. Baron (1977) defined such "aggressive behaviour as behaviour that is directed towards the goal of harming or injuring another living being who is motivated to avoid such treatment".

Historically, Thomas Hughes's 1857 novel Tom Brown's School Days details intensive school bullying, but the first major scholarly journal article to address school bullying appears to have been written in 1897. Research in school bullying has dramatically expanded over time, rising from 62 citations in the 90 years between 1900 and 1990, to 562 in the 4 years between 2000 and 2004. Since 2004, research on school bullying has mushroomed. 2022 TV series The Glory drew renewed attention to the phenomenom.

Criteria

Bullying is a subcategory of aggressive behavior that is characterised by hostile intent (the harm caused is deliberate), imbalance of power (real or perceived power inequality between bully and victim), and repetition over a period of time. More ordinary types of student-student conflicts, which are sometimes part of everyday school life, are not associated with an imbalance of power. In contrast to more ordinary conflicts, school bullying can severely harm victimized students.

Difference between normal peer conflicts and bullying victimization and implications for teachers

Power imbalance

By definition, bullying involves an imbalance of power. A bully has power over another student because of factors such as size, gender, age, standing among peers, and/or assistance by other students. Among boys, bullying tends to involve differences in strength; among girls bullying is more focused on differences in physical appearance, emotional life, and/or academic status.

Some bullies target peers with physical impairments, such as speech impediments (e.g., stuttering). Many stutterers experience some degree of bullying, harassment, or ridicule from peers and, sometimes, teachers.

Warning signs

Signs that a child is being bullied may include:

Signs that a child is bullying others may include:

  • Getting into physical or verbal fights,
  • Getting sent to the principal's office frequently,
  • Having friends who bully others, and
  • Becoming increasingly aggressive in normal activities.

Signs that a child has witnessed bullying include:

  • Poor school behavior,
  • Emotional disturbance,
  • Depression,
  • Post-traumatic stress,
  • Drug and alcohol abuse, and
  • Suicidal ideation.

Control of bullying

There are two main methods employed in controlling bullying: Prevention (acting before something happens) or reaction (acting when something is happening or has just happened).

Preventative solutions may include:

  • Education: The education of students, parents, and teachers as to what constitutes bullying may help people understand the harmful nature of bullying. Teachers, school bus drivers, and other school professionals are taught how and when to intervene. Examples of activities used to teach students about bullying include: presentations, role-play, discussions about identifying and reporting bullying, teaching bystanders how and when to help, use of arts and crafts to build understanding of the effects of bullying, and classroom meetings to talk about peer relations. A systematic review found that bullying is an indicator for later criminal behaviour, regardless of other major childhood risk factors, suggesting that anti-bullying programmes may be viewed as a form of early crime prevention.
  • Restrictions on recording devices: It has been suggested that the use of mobile phones can lead to an increase in cyberbullying, which is why some schools have banned them throughout the school day.
  • Security technologies: Schools may opt to install video cameras to monitor behaviour. However, skeptics argue that cameras may invade the students' privacy, especially if lax restrictions on the longevity of, and access to, the recordings leads to their misuse.
  • Guards in the school: Schools may choose to employ internal security guards or watchmen to ensure the students' safety. Experts believe that the use of security guards inside the schools may assist in reducing incidents of bullying as the guards get to know the students and who may then be able to predict and prevent issues before they arise.

The recommended reactions to cases of bullying are manifold, and various methods may be called for, depending on the type of bullying, and the people who are involved. Some suggestions for appropriate reaction are:

  • Avoid rigid confrontations: It is recommended that bullies not be met with physical violence, to avoid contributing to promoting the apparition of violent environments in society.
  • Reports of the witnesses: Witnesses, whether known to the victim or not, are an important source of information in cases of bullying. It is recommended that anonymity be maintained where possible.
  • Intervention by a bystander: It is recommended that bystanders, and other third persons, avoid intervening in a conflict situation, due to their potential to aggravate the situation.
  • Parental response: Experts advise that involved parents avoid talking directly to each other. Instead it is recommended to contact the school and allow the appropriate school personnel to take action, assume responsibility, and act as a mediator.
  • Teacher response: Teacher interventions are considered important in many anti-bullying programs. In many countries teachers have a legal obligation to prevent their students from harm. Teachers can intervene by using authority-based interventions, by using non-punitive approaches to bullying, by supporting victims, and by involving other teachers or professionals. Some other teacher interventions have been found to be helpful in reducing bullying. These interventions include clearly pointing out boundaries, making it clear that the behavior exhibited is not acceptable, and involving school principals. Discussing school bullying and the associated negative consequences with the entire class has also been found to be helpful in reducing bullying.
  • Suspension and Expulsion: Where no other solution for bullying is working, or in cases where the bullying is very severe, it maybe necessary to suspend or expel the offender. Severe measures such as detention, expulsion, and suspension could however also have iatrogenic effects and increase aggression.
  • Moving: In cases that are more difficult to solve, the victim may consider a change of institution or even moving with his or her family to another location.
  • Psychosocial support: After the bullying ends, victims of bullying may require support, such as help with making new friends and/or taking up new activities.

Types of bullying

There are a number of ways in which school bullying takes place. These include verbal, physical, psychological, cyber, and sexual bullying. Direct bullying refers to an open physical or verbal attack on a victim. Indirect bullying is more subtle and harder to detect, but involves one or more forms of relational aggression, including social isolation via intentional exclusion, spreading rumors to defame the target's character or reputation, making faces or obscene gestures behind the target's back, and manipulating friendships or other relationships. Pack bullying is bullying undertaken by a group. There is evidence that pack bullying was more common in high schools than in lower grades and lasts longer than bullying undertaken by individuals.

A female bully, portrayed in the 1917 silent film Rebecca of Sunnybrook Farm

Physical

Physical bullying is any unwanted physical contact between the bully and the victim. This is one of the most easily identifiable forms of bullying. Examples include: fighting, hazing, headlocks, inappropriate touching, kicking, pinching, poking, hair pulling, punching, pushing, slapping, spitting, stalking, or making unwanted and persistent eye contact with a victim, spilling liquids onto a victim, throwing small and lightweight objects at a victim, teasing, threatening, tickling, using weapons including improvised ones, theft and/or damaging of personal belongings.

Emotional

Emotional bullying is any form of bullying that causes damage to a victim's psyche and/or emotional well-being. Examples include: spreading malicious rumors about people, "ganging up" on others (this could also be considered physical bullying), ignoring people (e.g. the silent treatment or pretending the victim is non-existent), provoking others, belittling or saying hurtful things (which are also forms of verbal bullying).

Verbal

Verbal bullying are slanderous statements or accusations that cause the victim undue emotional distress. Examples include: foul language or (profanity) directed at the victim; using derogatory terms or deriding the person's name; commenting negatively on someone's looks, clothes, body, etc., (personal abuse); tormenting, harassing, mocking and belittling, threatening to cause harm, taunting, teasing, and making inappropriate sexual comments.

Cyberbullying

Coupled with the increasing use of computers and the internet, the use of such technology and social media has moved some bullying from the schoolyard to the internet. According to the website Stop Cyberbullying, schools experience difficulties in controlling off-campus bullying due to the perception that their role stops at the gates of the schoolyard. Schools are under pressure to not exceed their authority and to avoid violating students' right to free speech. Suggestions have been made that principals act to include cyberbullying in their code of ethics, allowing disciplining of bullying outside of school facilities and according to Professor Bernard James, "the timidity of educators in this context of emerging technology is working in the advantage of the bullies." Educators do appear to have support from the students. For example, three high school students from Melville, New York, organized a Bullying Awareness Walk, where several hundred people turned out to show their support.

Researcher Charisse Nixon found that students do not reach out for help with cyberbullying for four main reasons:

  • They do not feel connected to the adults around them
  • The students do not see cyberbullying as an issue that is worth bringing forward
  • They do not feel the surrounding adults have the ability to properly deal with the cyberbullying
  • The teenagers have increased feelings of shame and humiliation regarding the cyberbullying.

Research suggests that cyberbullying is sometimes an extension of bullying already taking place elsewhere. Students who are cyberbullied have, in many cases, also been bullied in other ways before (e.g., physically or verbally at school). There are few students who are bullied exclusively over the Internet. Some cyber victims are physically stronger than cyber bullies, which leads these bullies to prefer online confrontations to face-to-face contact.

Sexual

Sexual bullying is "any bullying behaviour, whether physical or non-physical, that is based on a person's sexuality or gender." A BBC Panorama questionnaire aimed at English teens aged 11 to 19 found that, of the 273 respondents, 28 had been forced to do something sexual, 31 had seen it happen to someone else, and 40 had experienced unwanted touching. U.K. government figures show that in the 2007–2008 school year, there were 3,450 fixed-period exclusions and 120 expulsions from schools in England due to sexual misconduct. This included incidents such as groping and using sexually insulting language. From April 2008 to March 2009, ChildLine counselled a total of 156,729 children, 26,134 of whom spoke about bullying as a main concern and 300 of whom spoke specifically about sexual bullying. Sexting cases are also on the rise and have become a major source of bullying and the circulation of explicit photos of those involved, either around school or on the internet, put the originators in a position to be scorned and bullied.

Bullying in higher education

About 15 percent of college students claim to have been victims of bullying. The misconception that bullying does not occur in higher education began to receive attention after the suicide of college student Tyler Clementi. According to a recent study, around 21.5% of college students reported rarely being victims of cyberbullying while around 93.3% of students said they rarely bullied others.

Characteristics of bullies

Several main categories of bullying have been identified. Coloroso noted that some bullies need to feel superior to others (the "confident bully"). Bullies with low self-esteem often try to bring others down (the "social bully"). Other bullies appear tough but are cowardly; they tend to want to be seen as tough (the "fully armored bully").

Other factors associated with being a bully is lower school performance and higher self-esteem.

Characteristics of victims

Victims of bullying tend to be physically smaller, more sensitive, unhappy, cautious, anxious, quiet, and withdrawn. They are sometimes characterized as passive or submissive and might use self-depreciating or self-defeating humor styles. Possessing these qualities makes these individuals vulnerable, as they are seen as being less likely to retaliate.

Another risk factor for becoming a victim is low self-esteem; however, low self-esteem can also be a consequence of having been bullied. Victims of cyberbullying, on the other hand, may not have lower scores than uninvolved students but might have higher body-related self-esteem than both victims of traditional bullying and bullies.

Locations and contexts

Bullying locations vary. Most bullying in elementary school happens on the playground. In middle school and high school, it occurs most often in hallways, which have little supervision. According to the U.S Department of Education's National Center for Education Statistics, more than 47% of victims report being bullied in hallways and stairways. Bus stops and bus rides to and from school can also be sites of bullying; children tend to view the driver as someone with no disciplinary authority.

Roles

Cartoon representation of a bully and a victim used to depict Western European powers and the United States bullying Serbia in the aftermath of the 2008 Kosovo declaration of independence during the 2008 Serbian protests

McNamee and Mercurio state that there is a "bullying triangle," consisting of the person doing the bullying, the victim, and the bystander. Conversely, the US Department of Health and Human Services divides the participants into 7 actors, consisting of the initial "triangle" plus those who assist, those who reinforce the actions of the bully, those who aren't involved but witness the bullying ("outsiders"), and those who come to the assistance of the victim after the fact ("defenders").

Complex cultural dynamics

School bullying might not end with interaction between students; other dynamics may be visible within a school. Students may bully each other or others (teachers, staff, parents), but the students may also experience bullying from teachers or staff. These dynamics may also be in play between staff and teachers, parents and teachers, or any other combination thereof.

Effects

As a result of bullying, victims may feel depressed, anxious, angry, stressed, helpless, out of control, and may experience a significant drop in school performance, or, in rare cases, commit suicide (bullycide). They tend to feel more lonely and have difficulties adjusting to school. Over the long term, they may feel insecure, lack trust, exhibit extreme sensitivity or hypervigilance, develop mental illnesses such as avoidant personality disorder or post-traumatic stress disorder (PTSD), or develop other health challenges. They may also desire revenge, sometimes leading them to torment others in return.

Anxiety, depression, and psychosomatic symptoms are common among both bullies and their victims. Alcohol and substance abuse are at risk for developing later in life. People suffering from depression often feel better when they talk to others about their lives; victims of bullying, however, may be reluctant to talk to others about their feelings because they fear being bullied for doing so, which can, in turn, worsen their depression.

In the short term, bystanders who witnesses bullying may experience anger, fear, guilt, and sadness. If they are witness to regular episodes of bullying, they may begin to exhibit the same symptoms as the victims themselves.

While most bullies, in the long term, grow up to be emotionally functional adults, many have an increased risk of developing antisocial personality disorder, which is linked to an increased risk of committing criminal acts (including domestic violence). Bullies have been shown to have higher levels of loneliness and lower levels of adjustment to school.

Educational quality and outcomes

The educational effects on victims of school violence and bullying are significant. Violence and bullying at the hands of students may make the victims afraid to go to school and interfere with their ability to concentrate in class or participate in school activities. It can also have similar effects on bystanders. Bullied students may miss classes, avoid school activities, skip school, or drop out of school altogether. Bullied students may also have lower grades, greater academic difficulties, and be less likely to anticipate going on to higher education. International analyses highlight the impact of bullying on learning outcomes, showing that bullying is related to lower achievement. Further, unsafe learning environments create a climate of fear and insecurity and a perception that teachers do not have control or do not care about the students, which reduces the quality of education for all.

Social and economic costs

The 2006 UN World Report on Violence Against Children shows that victims of corporal punishment, both at school and at home, may develop into adults who are passive and over-cautious or aggressive. Being bullied is also linked to a heightened risk of eating disorders and social and relationship difficulties. A 1958 study of children born in England, Scotland, and Wales looked at 7,771 children who had been bullied at ages 7 and 11 and found that by age 50, those who had been bullied as children were less likely to have obtained school qualifications and were less likely to live with a spouse or partner or to have adequate social support. These victims also scored lower in tests designed to measure cognitive IQ and were more likely to report that they had poor health.

The economic impact of violence against children and adolescents is substantial. Youth violence in Brazil alone is estimated to cost nearly US$19 billion every year, of which US$943 million can be linked to violence in schools, while the estimated cost to the economy in the USA is US$7.9 billion a year. Studies show that school-related gender-based violence alone can be associated with the loss of one primary grade of schooling, which translates to an annual cost of around US$17 billion to low- and middle-income countries. In Cameroon, Democratic Republic of Congo, and Nigeria it is estimated that US$974 million, US$301 million, and US$1,662 million respectively are lost due to failures in the equal education of girls and boys, with violence in school listed as one of the key factors contributing to the under-representation of girls in education. In Argentina, the cost of early dropping out is estimated to be 11.4% of GDP, and in Egypt, nearly 7% of potential earnings is lost as a result of the number of children dropping out of school. It is not clear how much of these preceding losses may be attributable to school bullying.

Statistics

Percentage of boys and girls who experienced bullying in the past 12 months

According to the American Psychological Association, "40% to 80% of school-age children experience bullying at some point during their school careers." Various studies show that students from lower socioeconomic backgrounds and students with disabilities experience bullying more often than other students.

Victims

  • Statistics show that in the U.S. school system 1 in 3 children are affected by bullying in their lifetime, and 30% report being involved in some manner.
  • In a 1997 study of five Seattle high schools, students recorded their peers' hallway and classroom conversations. It was discovered that the average high school student hears about 25 anti-gay remarks a day.
  • U.S. students who are homosexual, bisexual, or transgender are five times as likely to miss school because they feel unsafe after being bullied due to their sexual orientation or gender identity.
  • According to the U.S. Centers for Disease Control and Prevention, the percentage of gay, lesbian, and bisexual students who did not go to school at least one day during the 30 days preceding the survey, due to safety concerns, ranged from 11% to 30% for gay and lesbian students and 12% to 25% for bisexual students.
  • 61.1% of LGBT middle- or high-school students were more likely than their non-LGBT peers to feel unsafe or uncomfortable as a result of their sexual orientation.
  • In the United States, a 2013 nationwide survey indicated that 20% of high school students were bullied on school property in the past year, 15% of the students were bullied electronically, and 8% of students ages 12–18 reported ongoing bullying on a weekly basis.
  • According to the journal Evolutionary Psychological Science, victims of bullying are more likely to be sexually inactive compared to bullies.
  • In a Canadian study that surveyed 2,186 students across 33 middle and high schools, 49.5% reported being bullied online in the previous three months. 33.7% of the sample reported being the perpetrator of cyberbullying.
  • At least 1 in 3 adolescent students in Canada has reported being bullied.
  • 47% of Canadian parents report having a child who is a victim of bullying.
  • The most common form of cyberbullying involved receiving threatening or aggressive emails or instant messages, reported by 73% of Canadian victims.
  • A nationwide survey conducted by Trinity College Dublin, of bullying in first- and second-level schools in Ireland, estimates that some 31% of primary and 16% of secondary students have been bullied at some time.
  • In a study of 32 Dutch elementary schools, 16.2% of the 2,766 participating children reported being bullied regularly (at least several times a month).

Statistics referencing the prevalence of bullying in schools may be inaccurate and tend to fluctuate. In a U.S. study of 5,621 students ages 12–18, 64% of the students had experienced bullying and did not report it.

Bullies

  • In a 2005 survey, 3,708,284 students reported being a perpetrator of bullying in the U.S. school system.
  • Studies have shown bullies report having more friends than children who are victims.
  • Bullying behavior in perpetrators is shown to decrease with age.
  • Developmental research suggests bullies are often morally disengaged and use egocentric reasoning strategies.
  • Bullies often come from families that use physical forms of discipline. Adolescents who experience violence or aggression in the home, or are influenced by negative peer relationships, are more likely to bully. This suggests that positive social relationships reduce the likelihood of bullying.
  • Bullies may show signs of mental health disorders. This trend is most evident in adolescents diagnosed with depression, anxiety, or ADHD.
  • Poor theory of mind is associated with bullying.
  • Up to 25% of students may encourage bullying, and more than 50% will not intervene in bullying situations.
  • A study by Lisa Garby shows that 60% of bullies in middle school will have at least one criminal conviction by the age of 24.
  • 10.6% of surveyed children said they sometimes bullied other children (moderate bullying), 8.8% said they had bullied others once a week or more (frequent bullying), and 13% said they had engaged in moderate or frequent bullying of others. 6.3% had experienced bullying and also been a bully.

School shootings

Although research suggests that there might be a weak association between school bullying and school shootings, there is some evidence that having been a victim of school bullying is related to increased risk of a school shootings. The media have portrayed some individuals, such as Charles Andrew Williams, Eric Hainstock, Seung-Hui Cho, Eric Harris and Dylan Klebold, Luke Woodham, Michael Carneal, Wellington Menezes Oliveira, Karl Pierson, Jose Reyes, and Jeff Weise, as having experienced bullying and then becoming school shooters. However, research suggests that the vast majority of individuals who have been victims of bullying do not become school shooters.

Institutional prevention

Studies have shown that bullying programs set up in schools with the engagement of staff and faculty have been shown to reduce peer victimization and bullying. Incidents of bullying are noticeably reduced when the students themselves disapprove of bullying. Classroom activities where students reflect on bullying decrease the cases of bullying while increasing the communication between students and school staff.

The current literature shows that school-based anti-bullying programs are also effective in reducing bullying perpetration and bullying victimization by ~15%, based on moderate-quality evidence. However, as there is variation in the effectiveness of anti-bullying programs, further research is required to identify specific programmatic features that make programs effective.

Measures such as instituting zero tolerance for fighting or placing troubled students in the same group or classroom are actually ineffective in reducing bullying. Methods that are effective include increasing empathy for victims; adopting a program that includes teachers, students, and parents; and having students lead anti-bullying efforts. Success is most associated with beginning interventions at an early age, constantly evaluating programs for effectiveness, and having some students take online classes to avoid bullies at school. Another way to help victims is to provide peer support. Peer support can help a victim improve his or her school performance.

Effective national responses

Based on UNESCO case studies of six countries that have succeeded in reducing school violence and bullying (Eswatini, Italy, Jamaica, Lebanon, Republic of Korea and Uruguay) as well as two countries that have maintained low levels over time (the Netherlands and Sweden), there are a number of factors that contribute to effective national responses.

Factors that contribute to effective national responses include:

  • Political leadership and high-level commitment, together with a robust legal and policy framework that addresses violence against children and school violence and bullying. Many successful countries also have an emphasis in national policies that promote a safe learning environment, a positive school and classroom climate, and a strong commitment to child rights and empowerment.
  • Collaboration and partnerships. At the national level, this includes partnerships between the education sector and other sector ministries, civil society organizations, academic institutions, professional associations, and the media. At the school level, it includes partnerships involving all stakeholders in the school community, including head teachers, teachers, other staff, parents and students, local authorities, and professionals in other sectors. More specifically, the involvement of all students, including bystanders, and the use of peer approaches, have been a key factor in countries that have made the most progress.
  • Evidence-based approaches, informed by accurate and comprehensive data and systematic evaluation of the effectiveness of existing programmes. Effective systems for routine reporting and monitoring of school violence and bullying and rigorous evaluation of the impact of programmes and interventions are critical. Bullying prevention programs that reach parents through trainings and material sent home, as well as role-playing scenarios that students can work through, have been found as relevant components to reduce the problem behavior according to research from David Finkelhor and colleagues from the University of New Hampshire's Crimes Against Children Center.
  • Training and support for teachers and care and support for affected students. Training in successful countries has focused on developing skills to prevent and respond to school violence and bullying and to use positive approaches to classroom management.

The case studies also identified a number of factors that can limit the effectiveness and impact of national responses. These include lack of data on specific aspects of school violence and bullying and on the sub-groups of students who are most vulnerable, low coverage of interventions, lack of systematic monitoring of school violence and bullying, and of robust evaluation of the impact of programmes.

Some U.S. states have implemented laws to address school bullying.
  Law that prohibits discrimination against students based on sexual orientation and gender identity
  School regulation or ethical code for teachers that address discrimination and/or bullying of students based on sexual orientation and gender identity
  Law that prohibits discrimination against students based on sexual orientation only
  School regulation or ethical code for teachers that address discrimination and/or bullying of students based on sexual orientation only
  Law that prohibits bullying of students based on sexual orientation and gender identity
  Law that forbids local school districts from having anti-bullying policies that enumerate protected classes of students
  Law that prohibits bullying in school but lists no categories of protection
  No statewide law that specifically prohibits bullying in schools

Anti-bullying legislation and court rulings

United Kingdom

Section 89 of the Education and Inspections Act 2006 provides for an anti-bullying policy for all state schools to be made available to parents.

United States

The victims of some school shootings have sued both the shooters' families and the schools. At one point only 23 states had anti-bullying laws. In 2015, Montana became the last state to enact an anti-bullying law. At that point, all 50 states had an anti-bullying law. These laws are not going to abolish bullying, but it does bring attention to the behavior, and they let the aggressors know it will not be tolerated.

Canada

In 2016, a legal precedent was set by a mother and her son, after the son was bullied at his public school. The mother and son won a court case against the Ottawa-Carleton District School Board, making this the first case in North America where a school board has been found negligent in a bullying case for failing to meet the standard of care ("duty of care") that the school board owes to its students. A similar bullying case was won in Australia in 2013 (Oyston v. St. Patricks College).

Taiwan

The Ministry of Education has launched a series of projects. In 2006, they started the 'anti-bully plan'. In 2008, they launched the "prevent-bully video from public project"—which included encouraging informants and monitoring the school—in the hope that it could improve education quality.

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