Episodic effects on the visual comparison of letters in words

In two experiments, subjects compared the identity of either the first letters of displays or all the letters in displays. Words yielded faster decisions than did pseudowords (pronounceable items derived by changing a vowel in a word) only when entire displays were compared. In a training phase run before the comparison task, subjects had written down either the first letters or entire displays. Relative to items that had not appeared in the training phase, prior experience at writing entire displays facilitatedsame decisions about entire displays and interfered withdifferent decisions about entire displays. Prior experiences did not moderate the processing of first-letter identities. It was concluded that episodic effects arise from the interaction of higher order information underlying lexical encoding. Prelexical processing of letters is not sensitive to episodic effects.     

The effects of lexical and semantic information on same-different visual comparison of words

Previous research has indicated that phonemic and orthographic factors cannot account for the fact that words (clear/clear) are responded to more rapidly than orthographically legal nonwords (creal/creal) in a same-different visual comparison task. However, the role of semantic and lexical factors is less certain. The effects of semantic similarity on both same and different judgments were evaluated in several experiments. In the first experiment, subjects were not any slower on semantically related (rang/rung) than on unrelated (rang/rank) different judgments even with a 3,000-msec interval between the first and second word. In Experiment 2, subjects based their judgments on whether or not the first letter of each word was visually identical. Same judgments were not any faster for semantically related than unrelated items even though other evidence indicated that subjects were processing the whole word and not just the first letter. Experiment 3 showed that the word/orthographically legal nonword difference could be replicated with the first-letter visual comparison task employed in Experiment 2. These and related results were discussed with reference to the idea that the word/orthographically legal nonword difference is due to the facilitating effects of a lexical entry upon the encoding, but not the comparison of an item.     

Modeling the effects of choice-set size on the processing of letters and words

Letters and words are better identified when there are fewer available choices. How do readers use choice-set restrictions? By analyzing new experimental data and previously reported data, the author shows that Bayes theorem-based models overestimate readers' use of choice-set restrictions. This result is discordant with choice-similarity models such as R. D. Luce's (1963a) similarity choice model, G. Keren and S. Baggen's (1981) letter recognition model, and D. W. Massaro and G. C. Oden's (1979) fuzzy logical model of perception. Other models posit that choice restrictions affect accuracy only by improving guessing (e.g., J. L. McClelland & D. E. Rumelhart's, 1981, interactive activation model). It is shown that these models underestimate readers' use of choice-set restrictions. Restriction of choice set does improve perception of letters and words, but not optimally. Decision models that may be able to explain this phenomenon are discussed.     

Detection and identification of words and letters in simulated visual search of word lists

Ss were shown a rapid sequence of words and had to (a) make a speeded response to the presentation of a predefined target and (b) report a "response word" which they thought immediately followed the target in the sequence. In Experiment I presentation rate was varied orthogonally with the number of alternative targets. Detection errors and latency increased with target set size, as did the distance of the response word from the target in the list sequence. Increases in presentation rate produced greater target-response distance without affecting detection time. In Experiment II Ss were in some conditions given only the initial letter of the targets; the response could be either the whole word following the target or only its initial letter. The results indicated that Ss could, within limits, concurrently detect initial letters and identify words. Alternatives to hierarchical-type models of stimulus processing in visual search were discussed.     

Large auditory and small visual effects in the recall of consonant letters

Eighty-six adults serially recalled lists of visually presented consonant letters similar in auditory or visual features or dissimilar in both feature sets. There were significantly more errors at every auditory list position than at the corresponding visual and neutral list positions, which did not themselves differ. There was a positive correlation between the tendency toward phonetic coding and overall performance, with 75 subjects making more errors on the auditory list than either of the other lists. The eight subjects who made more errors on the visual list showed poor performance in the recall of all lists. Factors governing the perceivability of stimuli apparently do not continue to operate significantly in controlling their recallability, at least in the case of veridical visual input.     

Individual differences in visual discrimination of letters.

Research on the distinctive features of letters has been inconclusive. Investigators may have overlooked individual variations in their data which would have supported feature-extraction hypotheses but were concealed by analyses which averaged data into group means. Response latencies from a matching discrimination task with the 26 English capital letters were analyzed with INDSCAL, a multidimensional scaling procedure which weights individual contributions to a psychological space. Underlying a dimensions were linearity, curvature, angularity, and closure. The solution disclosed that individuals utilized these features differentially in the visual discriminations. The results suggest that future research in visual feature extraction will benefit from the examination of individual variations in the perceptual process.     

Processing letters in words at different levels

Subjects indicated whether two letters, two words, or a letter and the first letter of a word were the same. Letter targets were matched more quickly than word targets when the stimuli were presented simultaneously. When the target and comparison stimuli were separated by a 3-sec interval, word targets were matched more quickly than a letter and a letter in a word. It was also shown that the physical similarity of the targets and comparison stimuli had a greater effect in the simultaneous matching conditions. These findings are consistent with a model of word processing in which letters are individually compared prior to word identification at a physical level of processing. At a higher level of processing, words may be encoded as a unit, and the identification of the letters within the word may require a decoding of the word unit.     

Identification of letters in words and of single letters with pre- and postknowledge vs. postknowledge of the alternatives

Two experiments were conducted to test how the “word letter phenomenon” (WLP)—a letter is better identified when embedded in a word than when presented alone—is affected by prior knowledge of the alternatives in a forced choice paradigm with tachistoscopic exposures. In Experiment 1, one group of subjects, who were given knowledge of the alternatives after the display, showed the usual WLP. The WLP was eliminated in a second group of subjects who were given knowledge of the alternatives both before and after the display. In Experiment 2, the same subjects were either precued or not precued on alternating trials of each block. It appeared that the WLP suppression with precuing resulted from a decrease in word performance whereas letter performance was unaffected by precuing. It is suggested that precuing exerts a detrimental effect, because, instead of attending to the word as a whole, subjects search for where in the word the forced choice would be plausible.     

The effect of semantic priming on the detection of letters within words

Memory & Cognition - Smith (1979) reported an experiment in which subjects were to detect whether or not a displayed word contained a particular target letter. Her data indicated that if the...     

Familiarity affects visual processing of words.

While previous research has demonstrated that words can be processed more rapidly and/or more accurately than random strings of letters, it has not been convincingly demonstrated that the superior processing of words is a visual effect. In the present experiment, the cases of letters were manipulated in letter strings that were to be compared on the basis of physical identity. Mean response time was shorter for words than for nonwords even for pairs of letter strings that differed only in case (e.g., site-site). This finding implies that the advantage of words over nonwords (the familiarity effect) typically observed in the simultaneous matching task is not due solely to comparison of either the word names or the letter names and, thus, that at least part of the familiarity effect must be due to more rapid formation and/or comparison of visual representations of the two letter strings when they are words. Further analysis failed to reveal a significant involvement of phonemic or lexical codes in the comparison judgments.     

An alternative for judging confusability of visual letters.

Numerical values for shared distinctive features were derived from Gibson's (1) feature analysis of the 26 uppercase alphabet letters. Due to the lack of agreement among the empirical matrices, it is proposed that this more general table is a useful and practical approach for judging confusability of visual letters for uppercase items. Reaction time data from a Posner-type of letter-matching task support the effectiveness of the table for judging visual confusability among uppercase letters.     

Illusory words: the roles of attention and of top-down constraints in conjoining letters to form words

When attention is divided among four briefly exposed syllables, subjects mistakenly detect targets whose letters are present in the display but in the wrong combinations. These illusory conjunctions are somewhat more frequent when the target is a word and when the distractors are nonwords, but the effects of lexical status are small, and no longer reach significance in free report of the same displays. Search performance is further impaired if the nonwords are unpronounceable consonant strings rather than consonant-vowel-consonant strings, but the decrement is due to missed targets rather than to increased conjunction errors. The results are discussed in relation to feature-integration theory and to current models of word perception.     

Repetition effect in visual recognition of letters

This study examined the influence of the repetitive presentation of a letter on the recognition of two letters. In two experiments(4), two letters, which were either identical or not, were presented successively for a short duration at different spatial locations, and the subjects were required to identify them. In Experiment 1, the presentation time of the first letter was varied, whereas that of the second letter was constant. The results revealed that a reduced performance in identifying a second letter was observed in the case that the first letter, which was identical to the second letter, could be identified correctly. Experiment 2 examined whether or not this reduction was due to the identity of the visual shape of two letters. The first letter was presented either in the usual vertical orientation or rotated orientation by 180 degrees and the second letter was constantly presented in the usual orientation. The results revealed that a reduced performance in identifying a repeated letter was observed, regardless of the orientation of the first letter. The findings from the two experiments suggested that the identity of the information in memory was a main cause of the interference effect by repetition.     

Frequency effects with visual words and syllables in a dyslexic reader

The present study investigated the nature of the inhibitory syllable frequency effect, recently reported for normal readers, in a German-speaking dyslexic patient. The reading impairment was characterized as a severe deficit in naming single letters or words in the presence of spared lexical processing of visual word forms. Three visual lexical decision experiments were conducted with the dyslexic patient, an unimpaired control person matched to the patient and a control group: Experiment 1 manipulated the frequency of words and word-initial syllables and demonstrated systematic effects of both factors in normal readers and in the dyslexic patient. The syllable frequency effect was replicated in a second experiment with a more strictly controlled stimulus set. Experiment 3 confirmed the patient's deficit in activating phonological forms from written words by demonstrating that a pseudohomophone effect as observed in the unimpaired control participants was absent in the dyslexic patient.     

Visual comparison of words and random letter strings: Effects of number and position of letters different

Memory & Cognition - Ss classified tetragrams as either “same” or “differen”. Stimuli were either words or consonant strings. In the case of different pairs, the number...