Visual Similarity Effects Research Articles

Neglect Dyslexia for Numbers? A Case Report

Abstract We report the case study of a patient (YM) with a specific number reading deficit, but with fairly preserved number comprehension and calculation. YM exhibits a spatial error pattern akin to neglect dyslexia, making most of his reading errors and perseverations on the leftmost digit of any number. This and a strong effect of visual similarity on errors suggest a visual deficit. Yet number syntax is preserved: most productions are legal number names, and less errors are observed on digits 0 and 1 when they bear a silent or syntactic role. On the basis of a detailed account of the deficit, we propose a revision of McCloskey, Sokol, and Goodman's (1986) model of number reading. We further discuss the apparent contradiction between the symbolic and the spatial aspects of YM's reading deficit, and the adequacy of the concept of neglect dyslexia.

Visual Similarity Effects in Detecting Letter Rhymes

Previous demonstrations of "visual" effects in auditory tasks have been largely restricted to orthographic effects with word stimuli. As a result, explanations of such effects have centered around a shared orthography--the similarity of the spelling patterns at the ends of the words. In the present study, these effects were extended to single-letter stimuli. Subjects made rhyming decisions about pairs of letters presented auditorily. Visually similar letter pairs facilitated responses to rhyming pairs and inhibited responses to nonrhyming pairs. The results indicate that visual effects are not restricted to word stimuli and suggest that additive effects of visual similarity and shared orthography may be responsible for these findings.

Visual working memory in young children.

Five experiments investigated immediate memory for drawings of familiar objects in children of different ages. The aims were to demonstrate younger children’s greater dependence on visual working memory and to explore the nature of this memory system. Experiment 1 showed that visual similarity of drawings impaired recall in young (5-year-old) children but not in older (10-year-old) children. Experiment 2 showed that younger and older children were affected in contrasting ways when the temporal order of recall was manipulated. Experiment 3 explored a recency effect found in backward recall and investigated its sensitivity to the presentation modality of materials used to produce retroactive interference (RI). For younger children, recency was reduced by visual but not by auditory-verbal RI; for older children, recency was more sensitive to auditoryverbal RI. Experiment 4 confirmed the effect of visual RI on visual recency in young children and showed that the same RI had little effect on their recall of spoken words. These results confirm younger children’s dependence on visual working memory. A final experiment showed that the effects of visual similarity and visual RI are additive, suggesting that they reflect different modes of accessing stored visuospatial information. Implications of these findings for developmental issues and for the nature of visual working memory are discussed.

Effects of Stimulus Probability and Visual Similarity on Stimulus Encoding

Visual similarity, stimulus probability, and stimulus contrast were manipulated in two memory-scanning experiments to determine how stimulus probability affects encoding. Two hypotheses were tested: The first, a featural facilitation hypothesis, localizes the effect of stimulus probability on feature extraction; the second claims that stimulus probability has its effect on stimulus recognition. In both experiments, visual similarity was found to slow encoding, particularly under low-contrast conditions. This effect was larger for low probability stimuli than for high probability stimuli and increased as the difference in probability between two visually similar stimuli increased. These results are inconsistent with the featural facilitation hypothesis, but can be explained in terms of differential priming of internal recognition responses for members of the stimulus set, such that more probable members are more easily recognized.

Further evidence for priming in perceptual matching: temporal, not spatial, separation enhances the fast-same effect.

Sequential (vs. simultaneous) presentation of two letters in a physical-identity matching task enhanced the fast-same effect, but did not reduce the preponderance of false-“different” errors or the effect of visual similarity. Thus, the sequential enhancement of the fast-same effect involves an increased efficiency in encoding (d’) owing to letter repetition, as Proctor claimed, rather than a criterion shift (β), and it involves the visual code rather than the name code. The increased efficiency in detecting sameness with sequential presentation might result from spatial separation (e.g., reduced lateral interference and self-termination), though, rather than temporal separation (e.g., priming), However, such spatial factors as letter size and interletter spacing had no consistent effect on the speed advantage forsame pairs, and it was concluded that temporal, not spatial, separation enhances the fast-same effect on sequential trials, Consistent with the response-competition model (Eriksen, O’Hara, & Eriksen), responses were slower and more errorful to similar than to dissimilardifferent pairs, and were equally fast to dissimilar andsame pairs on simultaneous trials.

Further analysis of the Crist data on matching performance and the similarity structure of the stimulus set.

We argue that Crist's (1981) analysis of his data on letter matching is incomplete because he did not sufficiently distinguish overall context similarity from the similarity of the other letter present on a trial. That is, the separation of the effects of context similarity and visual similarity is required for a complete analysis. Accordingly, for different trials, modified indices of context similarity are derived and linear regression analyses made to determine the separate effects of context and visual similarity. The results of these analyses show that on different trials, visual similarity is much more predictive of latency than context similarity and that subjects must therefore be making visual similarity judgments, that considerably affect latency variation on these trials. Consequently, we argue that visual similarity judgment may be likewise affecting latency on same trials. However, some simple correlations indicate that context may be more predictive of latency on physically different same trials. We concluded that what can be said about context depends on the type of trial and that the comparative strength of name processing should also be assessed by the method described here.

Children's use of phonological encoding when reading for meaning.

The role of phonological recoding in children's reading was investigated by means of a task requiring comprehension of sentence meaning: The child's task was to decide whether a sequence of printed letter strings was a meaningful sentence or not. Meaningless sentences that are meaningful when phonologically recoded (e.g., He ran threw the street) produced more incorrect responses than did meaningless sentences that remain meaningless when phono­ logically recoded (e.g., He ran sew the street). The difference in error rates between the two sentence types diminished as a function of age. Control experiments showed that these results were not due to visual similarity effects, nor to imperfect ability to spell homophones. It was concluded that very young readers rely extensively on phonological recoding when reading for meaning; as they grow older, reliance on visual encoding becomes progressively more important.

The Effect of Visual and Acoustic Similarity on Short-Term Memory for Chinese Words

Four lists of Chinese words in a 2 × 2 factorial design of visual and acoustic similarity were used in a short-term memory experiment. In addition to a strong acoustic similarity effect, a highly significant visual similarity effect was also obtained. This was particularly pronounced in the absence of acoustic similarity in the words used. The results not only confirm acoustic encoding to be a basic process in short-term recall of verbal stimuli in a language other than English but also lend support to the growing evidence of visual encoding in short-term memory as the situation demands.

Visual and phonetic memory in preschool children: evidence for coding flexibility.

This study examined visual and verbal (phonetic) memory coding in 22 preschool children 4 to 5 yr. of age. A major goal was to determine whether these children would code visual items phonetically during input in a short-term memory task as older children and adults often appear to do. Items to be remembered were visually presented letters that varied in visual as well as phonetic similarity. Subjects labeled each letter during presentation, and serial recall was probed either visually or verbally. Recall scores were analyzed according to planned individual comparisons and a 4-factor analysis of variance: probe modality (visual, verbal) X visual similarity (low, high) X phonetic similarity (low, high) x serial position (1, 2, 3, 4). Data indicated (1) a significant detrimental effect of high phonetic similarity for subjects whose recall was probed verbally, (2) a significant facilitating effect of high visual similarity, and (3) significant interactions indicating differential effects of phonetic similarity and probe modality on the serial position curve. These findings suggest flexibility of coding in children of the age range tested.

Auditory and visual similarity effects in recognition and recall

The role of auditory and visual factors in short-term recall and recognition performance was evaluated. Auditory similarity, but not visual similarity, was found to be predictive of the probability of a correct response and response confidence for both types of tests. The results were interpreted as support for a single-trace model of recall and recognition performance.

Choice response times as functions of inter-item similarity, anchor level, and stimulus type

Stimuli drawn from response-defined interval scales of size dimension, lightness dimension, and the two dimensions combined were used to investigate effects of visual similarity, stimulus type, anchor level and practice upon two-choice response time (RT). Results indicated the following: (a) Mean RT was independent of the physical dimension(s) upon which alternative stimuli differed; and (b) although mean RT decreased ISO msec (19%) across the range of similarities investigated, error rate never approached the 10% limit considered tolerable in choice R T research.

Short-term memory: Effects of auditory and visual similarity

The effects of five variables on short-term memory for letters were studied: Auditory Similarity, Visual Similarity, Presentation Rate, Sequence Length, and Blocks of Trials. Performance varied directly with Presentation Rate and inversely with Sequence Length and Auditory Similarity. Performance improved over blocks with high auditory and high visual similarity, and decreased under the low conditions of these variables. The improvement is attributed to learning to ignore redundant cues and attend to dues that permit discrimination. The decrement is attributed to fatigue and/or waning attention.