Perceptual reference points for form and orientation in young infants: anchors or magnets?

In some domains, certain stimuli are especially salient and efficiently encoded and are referred to as reference points. One current issue concerns whether reference points are associated with regions of increased or decreased discriminability and function as either perceptual anchors or magnets. In two experiments utilizing the familiarization/novelty-preference procedure, the question of whether 3- to 4-month-old infants' representations of form and orientation information are structured by perceptual reference points and whether such reference points serve as anchors or magnets is examined. In Experiment 1, infants displayed above-chance discrimination performance for pairs of form stimuli that were equivalently distinct on a physical basis, but only when one member of each pair was a "good" form (i.e., diamond, square, or triangle). In Experiment 2, infants displayed above-chance discrimination performance for pairs of stimuli differing by 7.5 degrees of orientation, but only when one member of each pair was either horizontal or vertical. The combined results from the two experiments suggest that "simple" gestalts and main axes (i.e., horizontal and vertical) serve as perceptual anchors in young infants' representations of form and orientation information.     

Is dyslexia a visual perceptive disorder? New empirical data

Several studies have shown that a phonological deficit is the origin of developmental dyslexia, because dyslexics have important difficulties in mapping orthographic to phonological codes. However, visual criteria are still used for the diagnosis of dyslexia and to develop methods of intervention. This study attempts to determine whether there are visual problems in dyslexic children. To this aim, dyslexic children and children without reading difficulties, matched by chronological age, participated in two experiments. One study was based on the Reversal test and the other was a visual decision task in which participants had to decide whether two letters were the same or different. There were 40 pairs of letters, to measure reaction times and mistakes. The results showed that dyslexics had similar performance to controls in the detection of different visual stimuli. Developmental dyslexics do not appear to have visual perceptual problems, but a particular difficulty to retrieve the phonological code of graphemes.     

Perceptual and motor congruency effects in time–space association

It is well established that temporal events are represented on a spatially oriented mental time line from left to right. Depending on the task characteristics, the spatial representation of time may be linked to different types of dimensions, including manual response codes and physical space codes. The aim of the present study was to analyze whether manual response and physical space codes are independent of each other or whether they interact when both types of information are involved in the task. The participants performed a temporal estimation task with two lateralized response buttons in four experiments. In the first experiment, the target stimuli were presented on the left side, at the center, or on the right side of the space, whereas the reference stimuli were always presented centrally. The reverse situation was presented in the second experiment. In the third experiment, both stimuli were presented in opposite spatial positions (e.g., left–right), whereas in the last experiment, both stimuli were presented in the same spatial position (e.g., left–left). In all experiments, perceptual and motor congruency effects were found, but no modulation of the congruency effects was found when both the perceptual and motor components were congruent. The results indicated that physical, spatial, and manual response codes are independent from each other for time–space associations, even when both codes are involved in the task. These results are discussed in terms of the “intermediate-coding” account.     

Laterality effects in perceptual matching

Two experiments are reported in which Ss had to indicate whether pairs of simple geometric forms were “same” or “different.” In Experiment I the two forms were either both in the left visual hemifield or both in the right hemifield. Reaction times were unaffected by the locus of the stimuli. In Experiment 2, in addition to left and right pairs, there were pairs in which one of the stimuli was on the left and the other was on the right. Under these conditions, reaction times were faster for pairs totally on the left than for pairs totally on the right. The data support the notion that implicit scanning patterns are important in determining laterality differences. When such scanning is not involved and when simple nonverbal stimuli and responses are employed, laterality differences are eliminated.     

Isolating visual units in the perception of words and nonwords

In three experiments, reaction times for same-different judgments were obtained for pairs of words, pronounceable nonwords (pseudowords), and unpronounceable nonwords. The stimulus strings were printed either in a single letter case or in one of several mixtures of upper- and lowercase letters. In Experiment 1, the stimuli were common one- and two-syllable words; in Experiment 2, the stimuli included both words and pseudowords; and in Experiment 3, words, pseudowords, and nonwords were used. The functional visual units for each string type were inferred from the effects that the number and placement of letter case transitions had onsame reaction time judgments. The evidence indicated a preference to encode strings in terms of multiletter perceptual units if they are present in the string. The data .also suggested that whole words can be used as functional visual units, although the extent of their use depends on contextual parameters such as knowledge that a word will be presented.     

Differential effects of familiarity on judgments of sameness and difference

Ss indicated whether pairs of simultaneously presented objects were “same” or “different.” In Experiments 1, 2, and 3 the stimuli were pairs of letters, and familiarity was manipulated by showing the letters in either an upright or an upside-down orientation. In Experiments 4 and 5 the stimuli were pairs of trigrams, and familiarity was manipulated either by rotation or by selection according to rated meaningfulness. Analysis of reaction times indicated that familiar pairs were responded to more quickly than were unfamiliar pairs; however, this was true only for “same” judgments, not for “different” judgments. In addition, Experiment 3 indicated that familiarity influenced discrimination accuracy under conditions of tachistoscopic exposure. Finally, in Experiment 6 an effort was made to disentangle the effects of meaningfulness from the effects of pronounceability. The present results stand in contrast to previous research using perceptual comparison tasks, since the earlier work failed to indicate any effect of familiarity.     

Individual differences in the verbal coding of familiar visual stimuli

Two experiments were performed both of which involved the same-different comparison of pairs of alphabet letters. "Same" reaction times were obtained for both physical matches (e.g., AA) and name matches (e.g., aA). The results of both experiments supported the hypothesis that individual subjects would differ with respect to whether or not they based their physical matches on a comparison of verbal codes. In Experiment I, subjects differed in the size of their reaction time difference between physical and name matches, and in Experiment II, individuals differed with respect to whether or not the frequency of usage of the letters affected their reaction time for physical matches. In both experiments, the individual differences in verbally coding physical matches were related to Hock's (1973) individual differences distinction between subjects emphasizing analytic processes and subjects emphasizing structural processes.     

Induction and categorization in young children: a similarity-based model

The authors present a similarity-based model of induction and categorization in young children (SINC). The model suggests that (a). linguistic labels contribute to the perceived similarity of compared entities and (b). categorization and induction are a function of similarity computed over perceptual information and linguistic labels. The model also predicts young children's similarity judgment, induction, and categorization performance under different stimuli and task conditions. Predictions of the model were tested and confirmed in 6 experiments, in which 4- to 5-year-olds performed similarity judgment, induction, and categorization tasks using artificial and real labels (Experiments 1-4) and recognition memory tasks (Experiments 5A and 5B). Results corroborate the similarity-based account of young children's induction and categorization, and they support both qualitative and quantitative predictions of the model.     

Discriminations among perceptual and symbolic stimuli

This research compares the time required for perceptual discriminations among pairs of physically present objects (circles) with the time required to discriminate pairs of symbols Inonsense syllables) that subjects learned to associate uniquely with each of the circles. Four experiments show very large differences between symbolic and perceptual discriminations. Discrimination times for the perceptual stimuli declined systematically as their size ratio increased, but discriminations among the associated nonsense syllables showed only a strictly ordinal effect of position in the series. Discriminations among the symbolic stimuli showed a large semantic congruity effect, but the perceptual stimuli showed none. The research does not replicate previous results showing similarities between perceptual and symbolic processing suggestive of image processing. We conclude that in the symbolic task subjects use only ordinal information rather than images or analog representations of the associated circles. We propose that perceptual discriminations show a semantic congruity effect only when they are processed as if the perceptual stimuli were symbolic.     

Intuitive covariation estimation

Six experiments concerned people's ability to estimate the degree and sign of covariation represented in a bivariate distribution of stimuli with which they had just been presented as a series of pairs of stimuli. The stimuli were pairs of numbers, pairs of lines of variable lengths, or word-line pairs. In the latter case, subjects were asked to think of the words in terms of either pleasantness or familiarity; hence, the covariation relationship was between the normative pleasantness or familiarity value of the word and a line of variable length. In the sixth experiment, subjects were presented with two word-line pairs and were asked to access the covariation of both simultaneously. In most cases, the estimates reflected the sign and degree of covariation of the stimuli quite well. The estimates did not reflect accurately the stimulus covariation when the stimuli were numerical and the sign of the correlation of the stimuli was negative. A distinction is made between intuitive and strategic processes in the assessment of covariation.     

Perceptual and response interactions in semantic priming

In two experiments, subjects made pairs of lexical decisions verbally. In Experiment 1, masked stimuli appeared concurrently to the left and right of fixation; in Experiment 2, nonmasked stimuli appeared sequentially at fixation. The left-hand letter strings were judged more accurately in in Experiment 1, and the second letter strings were judged more accurately in Experiment 2. Each string in the pair could be either a word (e.g., fork) or a nonword anagram (e.g., frok). Consequently, the two strings in the pair could be related (e.g., fork-spoon, frok-spoon, etc.) or unrelated (e.g., fork-door, frok-door, etc.), independently of whether neither, either, or both strings were words. Semantically related stimuli induced consistent biases to respond "word," as noted in other studies. These biases were typically stronger for the event reported second. Minimal evidence was found for perceptual priming effects. The asymmetrical effects were consistent with spreading-activation-type mechanisms, but other considerations support a multiple-process view.     

Difference and ratio information in children's and adults' memory representations.

A study was made of the choice reaction times of 8-, 10-, 12-year-olds and adults in order to investigate whether length information stored in memory was coded to preserve numerical relations between stimuli. Subjects learned unique line length-color associations and were later presented with pairs of colors and were instructed to choose the color that had been associated with the longer line. For all age groups, choice reaction times were related to both differences and ratios. These results were interpreted as supporting the analog theory of representation.     

Young children's attention to global magnitude: evidence from classification tasks

Young children often compare objects holistically and not in terms of separate dimensions such as size and color. One holistic relation that often governs young children's object comparisons is overall similarity. Two experiments were conducted to examine the possibility that a holistic magnitude relation might also govern children's object comparisons. Objects varying on two dimensions of magnitude-size and saturation--were classified by 3-, 4-, and 5-year-olds. The results indicated that the younger children were sensitive to global magnitude as well as overall similarity. They grouped together large and saturated objects or small and desaturated objects more often than they did large and desaturated (or small and saturated) objects and thus appear to have been classifying by combined magnitude across both dimensions. This new finding that young children classify by a global relation of magnitude refines the understanding of perceptual development and provides information about the structure of perception. Young children's use of global magnitudes in classification also fits well with recent findings about children's acquisitions of dimension words.     

Semantic and surface codes in the memory of deaf children

In three experiments, deaf children in the age range of 6 years, 10 months to 15 years, 5 months were presented with continuous lists of items, and for each item they had to indicate whether it had appeared before on the list. Later items were related to preceding items either in surface form or in meaning or were unrelated. False-recognition errors (i.e., “yes” responses to new items) served as an index of memorial coding. In one experiment, the items presented to the subjects were printed words. The results of this experiment showed a false-recognition effect (i.e., more errors to related words than to unrelated words) for both semantically related words and orthographically similar words. In the other two experiments, the subjects viewed a series of manual signs on videotape. In these experiments, there was a false-recognition effect for signs related semantically and for signs related cherologically (i.e., similar in terms of their manual production). These results establish orthography and cherology as effective memorial codes for deaf children. The finding of a consistently strong semantic effect for young deaf children stands in contrast to findings of weak semantic effects in false-recognition studies with young hearing children. The ascendancy of semantic codes for deaf children was attributed to the absence of competition from the speech code which dominates the linguistic memory of hearing children.     

The effects of negative relatedness upon word-picutre and word-word comparisons and subsequent recall.

In two experiments subjects were required to compare the meanings of either a word and a picture, or of two words. Different name levels, i.e. category versus superordinate names, had only a small effect on the time to compare a name with a picture. When incongruent stimulus pairs were semantically related, both positive and negative decision times were longer than when the incongruent pairs were unrelated; relatedness also affected subjects' recall of stimuli. Implications for models of semantic decision are discussed.     

Developmental trends in utilizing perceptual closure for grouping of shape: effects of spatial proximity and collinearity

In two experiments, visual search was used to study the grouping of shape on the basis of perceptual closure among participants 5-23 years of age. We first showed that young children, like adults, demonstrate an efficient search for a concave target among convex distractors for closed connected stimuli but an inefficient search for open stimuli. Reliable developmental differences, however, were observed in search for fragmented stimuli as a function of spatial proximity and collinearity between the closure-inducing fragments. When only closure was available, search for all the age groups was equally efficient for spatially close fragments and equally inefficient for spatially distant fragments. When closure and collinearity were available, search for spatially close fragments was equally efficient for all the age groups, but search for spatially distant fragments was inefficient for younger children and improved significantly between ages 5 and 10. These findings suggest that young children can utilize closure as efficiently as can adults for the grouping of shape for closed or nearly closed stimuli. When the closure-inducing fragments are spatially distant, only older children and adults, but not 5-year-olds, can utilize collinearity to enhance closure for the perceptual grouping of shape.     

Coherence masking protection for speech in children and adults

In three experiments, we tested the hypothesis that children are more obliged than adults to fuse components of speech signals and asked whether the principle of harmonicity could explain the effect or whether it is, instead, due to children's implementing speech-based mechanisms. Coherence masking protection (CMP) was used, which involves labeling a phonetically relevant formant (the target) presented in noise, either alone or in combination with a stable spectral band (the cosignal) that provides no additional information about phonetic identity and is well outside the critical band of the target. Adults and children (8 and 5 years old) heard stimuli that were either synthetic speech or hybrids consisting of sine wave targets and synthetic cosignals. The target and cosignal either shared a common harmonic structure or did not. An adaptive procedure located listeners' thresholds for accurate labeling. Lower thresholds when the cosignal is present indicate CMP. Younger children demonstrated CMP effects that were both larger in magnitude and less susceptible to disruptions in harmonicity than those observed for adults. The conclusion was that children are obliged to integrate spectral components of speech signals, a perceptual strategy based on their recognition of when all components come from the same generator.     

Auditory temporal perception, phonics, and reading disabilities in children

Reading-impaired and control children were given an experimental battery of nonverbal auditory perceptual tests which examined discrimination and temporal order perception. Stimulus tones were presented at various rates. There were no significant differences between groups on tests in which stimuli were presented at slow rates. However, when the same stimuli were presented more rapidly, the reading-impaired group made significantly more errors than the controls. The reading-impaired children's ability to use phonics skills (nonsense word reading) was also examined. There was a high correlation between the number of errors made on the phonics reading test and the number of errors made in responding to the rapidly presented stimuli in the auditory perceptual tests. The hypothesis that some reading impairments are related to low-level auditory perceptual dysfunction that affects the ability to learn to use phonics skills adequately is discussed.     

They call it like they see it: spontaneous naming and attention to shape

Two experiments explore children's spontaneous labeling of novel objects as a method to study early lexical access. The experiments also provide new evidence on children's attention to object shape when labeling objects. In Experiment 1, the spontaneous productions of 21 23- to 28-month-olds (mean 26;28) shown a set of novel, unnamed objects were analyzed both in terms of the specific words said and, via adult judgments, their likely perceptual basis. We found that children's spontaneous names were cued by the perceptual feature of shape. Experiment 2 examines the relation between spontaneous productions, name generalizations in a structured task, and vocabulary development in a group of children between 17 and 24 months of age (mean 21;6). Results indicate that object shape plays an important role in both spontaneous productions and novel noun generalization, but contrary to current hypotheses, children may name objects by shape from the earliest points of productive vocabulary development and this tendency may not be lexically specific.     

Lateralization of lexical codes in auditory word recognition

Three experiments examined the lateralization of lexical codes in auditory word recognition. In Experiment 1 a word rhyming with a binaurally presented cue word was detected faster when the cue and target were spelled similarly than when they were spelled differently. This orthography effect was larger when the target was presented to the right ear than when it was presented to the left ear. Experiment 2 replicated the interaction between ear of presentation and orthography effect when the cue and target were spoken in different voices. In Experiment 3, subjects made lexical decisions to pairs of stimuli presented to the left or the right ear. Lexical decision times and the amount of facilitation which obtained when the target stimuli were semantically related words did not differ as a function of ear of presentation. The results suggest that the semantic, phonological, and orthographic codes for a word are represented in each hemisphere; however, orthographic and phonological representations are integrated only in the left hemisphere.