User:Ashar29/sandbox

=Orthographic priming (Psychology)= Orthographic priming is a topic studied extensively within the field of cognitive science. This is a scientific discipline devoted to the investigation of how the mind operates and the processes it undergoes. Orthographic priming is specifically analyzed in the subfield of linguistics, which refers to the scientific study of human language. Research involving orthographic priming arose due to interest in visual word recognition processes that humans undergo while reading.

Orthography is defined as the conventional spelling system of a given language and how certain letters and symbols are used to express sounds and form proper words. Each language has its own orthography. Priming refers to the presentation of a stimulus (a prime) in order to influence the response to a subsequent stimulus (a target). Exposure to a prime is expected to induce an implicit memory effect if the prime and target are similar in some way. Information in long-term memory related to the prime becomes more easily accessible following exposure to the prime. Orthographic priming is one of many types of priming (others include but are not limited to semantic priming, repetition priming, associative priming and response priming). This form of priming specifically influences visual word recognition as it makes use of orthography. Orthographic priming is a technique that uses a visual prime that is similarly spelled to a target word. Usually the prime and target words share all the same letters except for one. This type of priming is often used in word recognition tasks. The objective of orthographic priming is to establish a priming effect, that is, demonstrate that word recognition is faster and/or easier following exposure to a similarly spelled word. This priming effect has been demonstrated in various word recognition studies. For example, word targets preceded by orthographically similar word primes (i.e. farm-BARN) have been shown to be easier to recognize than target words preceded by orthographically dissimilar words (i.e. castle-BARN). This word recognition facilitation effect has also been shown to occur with the use of non-word primes. Recognition of target words is improved when an orthographically similar non-word prime is used (i.e. fibe-VIBE) than when an orthographically dissimilar non-word prime is used (i.e. zarn-VIBE).

Theory
It has been suggested that the orthographic priming effect occurs because recognition of printed words involves preliminary processing of letter components and their positioning in the letter strings. Providing information regarding a target word's component letters (with the use of an orthographically similar prime) before exposure to the actual word will therefore facilitate recognition. Evidence of the orthographic priming effect has been found in numerous studies, which ultimately strengthens this theory. Additionally, the concept of a mental lexicon has been used to account for orthographic priming effects. This mental lexicon refers to a mental dictionary contained in individuals' long-term memory stores, comprised of all words they know, as well as their meanings, pronunciations, and spellings. A single node represents each known word. Words in the mental lexicon are arranged in terms of similarity, with orthographically similar words close together in proximity. During orthographic priming, the node representing the prime becomes activated and through a process of spreading activation, orthographically similar words near the prime also become partially activated. This partial activation is what is hypothesized to facilitate word recognition in orthographic priming

Research paradigms
Various research paradigms have been applied to study orthographic priming. The majority of studies measuring this effect have made use of the masked priming procedure in word recognition tasks. In this paradigm, a participant is presented with a mask, which is usually a row of hashmarks (i.e. "####") for approximately 500 ms, followed by a prime presented in lowercase letters for 50 ms, and finally the target word presented in uppercase letters. The purpose of the mask is to make the prime less visible. The participant should not consciously perceive the prime, which is why it is presented for an extremely brief period of time. This is to ensure any priming effect established is not the result of the participant consciously detecting the relationship between the prime and target. The masked priming paradigm is most commonly used in three different recognition tasks; the lexical decision task, the naming task, and the perceptual identification task.

For orthographic priming, the lexical decision task is used most frequently. This task requires participants to decide if a presented set of letter strings represents a real word or a non-word as quickly as possible. Participants are exposed to a mask, followed by a prime and then the target word. They must decide if the target represents a word or non-word. Two conditions are used, one where the prime is orthographically similar to the target word and one where it is not. Reaction time is measured and compared across conditions.

The naming task is a slightly modified version of the lexical decision task. Participants are presented with a mask, followed by prime and then a target word, however they must name the target word as quickly as possible rather than determine whether it is a word or non-word. Reaction time is measured and orthographically similar and dissimilar primes are compared. In both the lexical decision task and the naming procedure, the target word appears in the participants view until they respond to it.

Another method sometimes used is the perceptual identification task. This method exposes participants to a prime followed by a target word, however the target word is only presented for a brief period of time (500 ms) and is then replaced with a mask. Participants are then required to report what the target word was in order to evaluate if they perceived the stimulus

Studies have demonstrated that participants primed with words orthographically similar to target words respond faster and with fewer errors while performing the lexical decision task and naming task in comparison to when the primes are orthographically dissimilar. Participants also have a higher percentage of correct responses in the perceptual identification task when an orthographically similar prime is used

History
Jonathan Grainger is a prominent researcher in the field of cognitive science who has dedicated much of his career to studying word recognition and orthography. He has conducted key experiments that have contributed to a greater degree of understanding of these topics Most of his research has focused on factors that facilitate and inhibit word recognition. He has demonstrated the existence of the orthographic priming effect by conducting numerous studies and making use of a variety of research paradigms such as the ones listed above. Of particular interest to him was the orthographic neighbourhood frequency effect. This phenomenon illustrates when orthographic priming may have an inhibitory effect on word recognition. Two words are considered orthographic neighbours if only one letter differentiates them. The orthographic neighbourhood frequency effect suggests that recognition of words is impaired if the words have many high frequency orthographic neighbours. For example, recognition of the word "blur" would be impaired as it is orthographically similar to the word "blue", which is a high frequency word in the English language. Grainger's work has shown that in addition to orthographic similarity of prime and target stimuli, the number of frequent orthographic neighbours a prime and target word share influences the speed of word recognition. If a prime and target word have many frequent orthographic neighbours in common, the priming effect on word recognition is inhibited.

According to the interactive activation model, the neighbourhood frequency effect occurs due to a lateral inhibition mechanism. Upon presentation of a prime, all orthographic neighbours become activated in long-term memory. If many orthographically similar neighbours become activated, this slows down target word recognition, as the target word must compete with all other orthographic neighbours. Additionally, if any of the orthographic neighbours are high frequency words, they will inhibit target word recognition even more, as high frequency words are more easily accessible from long-term memory than words which appear infrequently.

In addition to neighbourhood frequency, Grainger's research has shown that orthographic priming is affected by the number of letters shared by prime and target stimuli as well as the number of letters present in the prime and not in the target word. Facilitation of word recognition is heightened when the prime and target words have more common letters. Research conducted by Grainger has provided important insight regarding the mechanisms behind word recognition and how orthography can facilitate and inhibit this process. He currently conducts his research in France at the Aix Marseille University. His research has served as a foundation for current studies analyzing this topic.

Additional facilitating and inhibitory factors
Several other factors have been shown to influence how orthographic priming effects word recognition. When a prime is presented long enough for participants to consciously perceive it, facilitation of target word recognition is inhibited. Presumably, this is because the prime competes with the target word, thus inhibiting recognition. However, the priming effect remains if partial word primes are used instead of full words (i.e. floo-FLOOR). Presumably, this is because no specific word competes with the target word. Additionally, orthographic priming is stronger when the prime and target words share initial letters compared to final letters. Therefore the prime-target combination blue-BLUR would have a stronger orthographic priming effect than blue-CLUE.

Recent findings and current research
Recent studies have taken evidence of the orthographic priming effect and used it to investigate what other factors interact with orthography to facilitate word recognition. Exploring how phonology influences orthographic priming has been a common approach. It was discovered that various studies that demonstrated the existence of an orthographic priming effect used primes that were not only orthographically similar to target words but also phonologically similar. That is, the primes also sounded similar to the target words, creating an orthographic-phonological overlap. Researchers became interested in separating the effects of orthographic priming from phonological priming to evaluate how this influenced word recognition. Orthographic priming was found to occur independently of phonological priming. Primes that are orthographically similar but not phonologically similar to target words still show a priming effect. Although phonological priming has been documented to facilitate word recognition as well, orthographic processing of the prime has been shown to occur before phonological processing. Orthographic units in the brain become activated earlier than phonological units after exposure to a word. Therefore if a prime were to be presented very briefly, orthographic priming would likely facilitate subsequent word recognition but phonological priming may not. Processing of phonological information would require a longer prime exposure time. Because orthographic processing occurs so early and automatically after exposure to a word, letter positioning and spelling must play a crucial role in word recognition and reading processes.

Studies have also demonstrated that using primes and targets that are homophones (words that sound the same but have different meanings/spellings) and are also orthographically similar to one another strongly facilitates visual word recognition. The priming effects found with orthographically similar homophones are stronger than those found in orthographic priming or phonological priming alone. This heightened effect is due to activation of both orthographic and phonological codes in the brain

Attention has also been directed towards how orthographic priming facilitates visual word recognition in bilinguals. Studies have shown that when a prime and target word are orthographically similar, but from two different languages, the same priming effect is found if the individual is a speaker of both languages. This suggests the same processes underlie first and second language processing

Neurological perspective and future research
With the advancement of modern day brain imaging and recording techniques, identifying the neural units and processes involved in orthographic priming is a fruitful avenue to explore. Studies have used event related potentials (ERP) to examine the time course of orthographic priming in masked priming paradigms. The ERP is a brain recording technique that measures the brain's overall electrical activity in response to the presentation of stimuli. This technique has indicated that orthographic processing can occur as soon as 150 ms following the exposure to a prime. Comparing this to phonological priming, it has been demonstrated that phonological processing arises approximately 50 ms later than orthographic processing. It is not yet known precisely what areas of the brain are specifically involved in orthographic processing. Studies have shown that orthographic activation is maintained in both cerebral hemispheres, however, the right cerebral hemisphere may be especially significant in processing. When comparing orthographic priming in the left and right visual fields, the priming effect is significantly larger in the left visual field. Because brain wiring is contralateral (stimuli presented in the left visual field is processed by the right cerebral hemisphere), this shows that the right hemisphere in particular is critical. This contrasts with evidence that the left cerebral hemisphere predominately governs language ability. Further research is necessary to achieve a better understanding of how orthographic processing is represented spatially in the brain. The use of functional magnetic resonance imaging (fMRI) is a promising method for identifying these brain regions. This brain imaging technique creates a 3D image of the brain while participants engage in a particular task. Blood oxygen levels in brain regions are measured and this determines what brain areas are involved in the cognitive task. Areas with the most blood flow have the most neuronal activation. To this date, not much research has been conducted using fMRI during orthographic priming, however future studies can use this technique to isolate particular brain areas involved in orthographic processing.

Implications
Studying word recognition is a crucial line of research as it is a central process involved in reading. The field of cognitive science has produced an immense amount of literature on this topic because understanding reading processes is thought to be an imperative task. Reading is an everyday practice, therefore understanding the mechanisms involved in it, as well as establishing what facilitates and inhibits it, is essential. An impaired ability to read, as found in surface, deep, or developmental dyslexia, is debilitating. Understanding ways to facilitate word recognition can help improve the lives of those who suffer from these impairments. Because orthography has shown to play a key role in word recognition, studying orthographic priming is a necessary endeavour. Additionally, there is a great amount of ongoing debate regarding the neural processes involved in word recognition. Traditional approaches assume the existence of a mental lexicon that drives this process, however modern day connectionist models cast doubt on the existence of this mental dictionary. These models suggest words correspond to patterns of activation among many nodes in the brain as oppose to one node per word. Further research focussing on priming and word recognition is necessary in order to refute or strengthen these theories of word reading. Knowledge accumulation is expected to result from from future orthographic priming experimentation.