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Chapter 6

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McGill University
PSYC 340
Debra Ann Titone

Chapter 6: Recognizing Visual Words Introduction • We are not just interested in discovering how we decide if a printed string of letters is familiar or not, but also how all the information that relates to a word becomes available • Magic Moment: point in time where a person has recognized a word but not yet had access to its meaning. (Balota, 1990). A word’s meaning can only be accessed after it has been recognized. • Johnson-Laird (1975): depth of lexical access may vary. • Gerrig (1986): different “modes of lexical access” in different contexts (ie- when we are reading something and getting very little sense from it) • Spoken vs. written Language: speech signal is only available for a short time, whereas a written word is often available for as long as the reader needs it. • But facilitation of recognition by words related in meaning is found in studies of both spoken and visual word recognition, and selecting the appropriate meaning of an ambiguous word is a problem for both visual and spoken recognition • Literacy is an important feature of modern civilization Studying Eye Movements in Reading • Important in helping us understand both how we recognize words and process larger units of printed language • Limbus tracking: infra-red beam is bounced off the eyeball and tracks the boundary between the iris and the white of the eye (limbus). Good at tracking horizontal eye movements, but poor at tracking vertical ones. • Purkinje system: accurate at tracking both movements. There are several sources of reflection from the eye (cornea, back of lens): System computes the movments of the exact center of the pupil from this information • Saccades: when we read, the eye travels in jumps of about 20 to 60 ms in duraciton, with intervals of 200-250 ms when the eye is still. • Fixations: when the eye is still • Very little info is taken in while the eye is moving in a saccade. During fixation, 15 characters to the right and 3-4 to the left in English speakers. • Asymmetry reversed for those who read from right to left. • Skilled readers may be able to take in more info • Fovea: most sensitive part of the visual field, corresponds to the central seven characters of average size text .Fovea is surrounded by the parafovea (extending 5 degrees on either side of the fixation point), where visual acuity is poorer. Beyond that is the periphery (even poorer visual acuity). Extract most of the meaning of what we read from foveal region. • Rayner and Bertera (1979): moving mask: creates a moving blindspot. Even if the fovea was masked, the reading was possible from the parafoveal region, but at a greatly reduced rate (12 words a minute). • If both the foveal and parafoveal region were masked, no reading was possible: participants knew there were strings of letters outside the masked portion and could sometimes pick up on the occasional grammatical function word (and), or obtain info about start of words. • Most influential model of eye movement control: E-Z Reader model :visual processing, and oculomotor control jointly determine when and where eyes move when we are reading. • When we read, fixate on a point, and then visual attention progresses across the line of text until a point is reached where the acuity limitations of the visual system then make it difficult to extract more info and recognize new words • Then, attention shifts and an eye movement is programmed into the oculomotor system to move to the point of difficulty. • Next, a saccade takes place to the new location, and the process is repeated. • Two stages of saccades: - 1) early labile stage, when planned saccade can be cancelled if it is no longer necessary (identified word in proposed target location) - 2) after labile stage, saccade cannot be cancelled. • Most controversial assumption to the E-Z Reader theory: attention is allocated to one word after another, in strictly serial fashion, shifting only after each word is identified  ensures that words are processed in correct order. • Word identification: 2 stages - 1) familiarity check: do I know this word: can trigger saccade - 2) full lexical access: retrieval of meaning, representation of word integrated with emerging linguistic structure: triggers shift in attention to next word. • Saccades and attention are decoupled in this model; have different sources of control (familiarity and identification) • Linguistic processing can affect eye movements- if analysis is wrong, might return to earlier location. Higher level processes intervene only when something goes wrong. Reaction time and other measures • Naming task: participants are visually presented with a word that they have to name; time it takes to start pronouncing the word aloud (naming latency) is measured. • Naming latencies: approx 500 ms. • Lexical decision task: participants must decide whether a string of letters is a word or a nonword. Displayed on computer screen- participant must press one key if it is a word and another key if it is a nonword. Experimenter measures reaction times and eror rates. • Problem: speed-accuracy trade-offs- faster a participant responds, more errors are made. • Absolute time is not very useful; more concerned with differences between conditions • Tachistoscopic identification: participants are shown words for a very short amount of time. • Researchers used to use a tachistoscope; now computers are used. • Experimenter records the thresholds at which participants can no longer confidently identify items. • Subliminal perception: behavior is affected although participants are unaware that anything has been presented. • Priming: presenting material before the word to which a response has to be made. • Most common: presenting one word prior to the target word. First word: prime. • Stimulus-onset-asynchrony (SOA): time between the onset (beginning) of a presentation of one stimulus and the onset of another. • Prime does not have to be a single word, and does not have to be linguistic What makes word recognition easier (or harder)? • Frequency effects and semantic priming are found in both spoken and visual word recognition Interfering with identification • Can slow down word identification by making it harder to recognize stimulus (ie: degrading its physical appearance- stimulus degradation) • Can be achieved by reducing the contrast between the word and the background, or by rotating word to an unusual angle. • Presenting another stimulus immediately after the target, interferes with recognition process (backwards masking) • If masking stimulus is unstructured (just a patch of randomly positioned black lights, burst of light): we call it energy. • If masking stimulus is structured (letters or random parts of letters): pattern masking • Energy masks operate on visual feature detection level: cause visual feature shortage and make feature identification difficult. Interfere at the letter level and limit time available for processing. • Perception without awareness: form of subliminal perception • Words that have been masked so that participants aren’t consciously aware of them sometimes produce an effect, even to the level of semantic processing. • Holender (1986): emphasized ensuring that participants are equally dark-adapted during the preliminary establishing of individual thresholds and the main testing phase of the experiment. Otherwise, cannot be sure that information is not reaching conscious awareness in testing phase. • As of yet, it is unclear whether we can identify and access meaning-related information about words without conscious awareness, but evidence leans in the direction • Can also present a word, but delay the presentation of one or two letters at the beginning of the word by backward masking those letters. • In English, after 60 ms, it doesn’t make much difference, but before that, delaying a consonant disrupts visual word recognition much more than delaying a vowel. • Early on, consonant identification is particularly important for recognizing a word. • In English, consonants have a more regular mapping from visual appearance to sound, whereas vowels do not. Frequency, familiarity and age of acquisition • Frequency of a word is v. important in word recognition. • Commonly used words more easily recognized, responded to more quickly. • Effect first demonstrated in tachistoscopic recognition • Whaley (1978): Frequency- single most important factor in determining speed of responding during the lexical decision task. • Effect of frequency is not just a result of differences between frequent and very infrequent words, but also between common and slightly less common words • Kucera and Francis (1967): most popular norm of frequency, listing the occurrence per million of a large number of words in many samples of printed language. • There are frequency differences between versions of English, and between written and spoken frequency. • CELEX database: stored electronically, so searchable. Useful for making up lists of materials with specific characteristics • But all this is only an approximation to experiential familiarity (Gernsbacher, 1984) • I.e: approximation may not work for low-frequency words (psychologists might be very familiar with terms that have low frequency in general language) • Common words tend to be short • Frequency entangled with age-of-acquisition (AOA): age at which you first learn a word • Normally children learn more common words first, but there are exceptions (ie. Giant) • Later the AOA, the more difficult it is for someone with brain damage to produce the word. • Size of correlation between early learned items and frequency varies, from .68 to .38 • Has been suggested that frequency effects are really AOA effects, but some studies also suggested that AOA effects have not controlled adequately for frequency (not taking cumulative frequency into account- how often words will be encountered in a lifetime) • French study showed that AOA effects persist even when cumulative frequency is controlled for. • Probable that both AOA and frequency have effects on word processing. • AOA particularly affects word reading, but cumulative frequency has an effect on all tasks • Tasks involving redundancy and regularity in the input-out-put mappings (ie- reading, where letters map onto sounds in a predictable way) are less prone to AOA effects, and are sensitive to cumulative frequency. But tasks with less redundancy and regularity do show AOA effects. • Experiment: Ellis and Lambon Ralph: introduced items into the training regime at different times. Items learned early possessed an advantage independently of their frequency. • As a network learns more items, it becomes less plastic, and late items are not efficiently or as strongly represented, because they are more difficult to differentiate from items that have already been learned. Early learned items have a head start that enables them to develop stronger representations in the network. Late learned items can only develop strong representations if they are presented in high frequency. Word length • Gough (1972): during word recognition, letters are taken out of a short-term visual buffer one by one, at a rate of 15 ms per letter. Therefore, long words would seem to be harder to identify than short words. But length effect independent of frequency is hard to find. • Complication: 3 different ways of measuring word length: how many letters, how many syllables and how long it takes to say the word. • Previously, it was thought that there was clear evidence that longer words take longer to pronounce. But Weeks (1973) found that word length (measured in letters) had little effect on naming words when other properties were controlled for. • Thus, number of letters in a word has little effect for short words, but has some effect for words between 5 and 12 characters long. • Naming time increased as a function of the number of syllables in a word (Eriksen, Pollack and Montague, 1970) • We take longer to name pictures of objects depicted by long words, compared with pictures of objects depicted by short words. Neighborhood effects • N-statistic: number of words that can be created by changing one letter of a target word. • N is a measure of neighborhood size (density) • Makes words with a high N easy to recognize when other factors have been controlled for, although clear benefits are only found for low frequency words. • Rime part of neighbors seems to be particularly important in producing facilitation • Andrews (1997): neighborhood size has more effect than neighborhood frequency. Word-nonword differences: • Words are generally responded to faster than nonwords • Less plausible nonwords are rejected faster than more plausible nonwords (pseudowords: ie, they follow rules of word formation) Repetition priming • Once you have identified a word, it is easier to identify it the next time (repetition priming). Facilitates accuracy of perceptual identification and lexical decision response times. • Effect lasts up to several hours or longer • Repetition priming effects are stronger for low-frequency words than for high- frequency words (frequency attenuation) • Repetition effects have 2 components: brief lexical access effect (not sensitive to frequency) and long term episodic effect (sensitive to frequency) • We generally obtain facilitation by repetition priming only within one domain (visual or auditory), but semantic priming (by meaning or association) works across domains = episodic view. Form-based priming • If words share letters: orthographically related. • Seeing a word that looks like another word = orthographic priming or form-based priming • Difficult to demonstrate • Only effective with primes masked as short SOAs, so that prime wasn’t consciously perceived. • Efficacy of form-based primes depends on exact makeup of task. Can have inhibitory effect, as well, if visually similar words are in competition. • Form based priming is much easier to obtain if the prime is masked (because masked priming is a purer form of priming that has no contribution from conscious processing) Semantic priming • Identification of a word can be facilitated by prior exposure to a word related in meaning (semantic priming) • Identification made easier if it is immediately preceded by a word related in meaning. • Effect can be found across many tasks and not limited to visual word recognition • First word (prime) can speed up recognition of the second word (target) = facilitation • But prime can also slow down identification of target = inhibition • With very short intervals, priming can occur if the prime follows the target • If target was presented for 50 ms, followed 80 ms later by prime, there was no facilitation. But if the target was presented for only 30 ms, and followed 35 ms later by the prime, there was significant backward priming of the target. • Suggests that words are processed in a parallel if the time between them is short. • Semantic priming is a type of context effect : words are rarely read in isolation. • Processing might be speeded up if words related to the word you are currently reading are somehow made more easily available, as they are more likely to come next than random words. Other factors that affect word recognition • Grammatical category to which a word belongs • Imageability, meaningfulness, concreteness • Rubin (1980): frequency, emotionality and pronunciability are the best predictors of performance in experimental tasks • Whaley (1978): frequency, meaningfulness and number of syllables had effect on lexical decision times, although AOA can be important variable • Balota et al compared phonological, lexical and semantic variables on speeded visual word naming and lexical decision tasks. • They found that the contribution of the variables was highly task dependent. • Semantic variables are especially important in lexical decision • Also, syntactic environment affects word recognition (Garret, 1984) • Refer to page 178: (1) and (2): in both cases, the target word is semantically unpredictable from the context, but syntactic context affected lexical decision times so that people were slower to
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