Graphemes are perceptual reading units

Graphemes are commonly defined as the written representation of phonemes. For example, the word 'BREAD' is composed of the four phonemes /b/, /r/, /e/ and /d/, and consequently, of the four graphemes 'B', 'R', 'EA', and 'D'. Graphemes can thus be considered the minimal 'functional bridges' in the mapping between orthography and phonology. In the present study, we investigated the hypothesis that graphemes are processed as perceptual units by the reading system. If the reading system processes graphemes as units, then detecting a letter in a word should be harder when this letter is embedded in a multi-letter grapheme than when it corresponds to a single-letter grapheme. In Experiment 1A, done in English, participants were slower to detect a target letter in a word when the target letter was embedded in multi-letter grapheme (i.e. 'A' in 'BEACH') than when it corresponded to a single-letter grapheme (i.e. 'A' in 'PLACE'). In Experiment 1B, this effect was replicated in French. In Experiment 2, done in English, this grapheme effect remained when phonemic similarity between the target letter alone and the target letter inside the word was controlled. Together, the results are consistent with the assumption that graphemes are processed as perceptual reading units in alphabetic writing systems such as English or French.     

Syllable onsets are perceptual reading units

Syllable onsets are defined as the initial consonant or consonant cluster in a syllable (e.g., BR in BREAD). In the present study, using a letter detection paradigm and French words, we tested whether syllable onsets are processed as units by the reading system. In Experiment 1, we replicated Gross, Treiman, and Inman's (2000) result of observing no difference between the detection latencies of letters embedded in a multi-letter syllable onset (e.g., c in ECLATER) relative to a single-letter syllable onset (e.g., C in ECARTER). In Experiment 2, participants took longer to detect the target letter when it was in the second position of a multi-letter onset (e.g., L in TABLIER) than when it was a single-letter onset (e.g., L in ECOLIER). In Experiment 3, this position effect was replicated for graphemes. In Experiment 4, we tested and ruled out an alternative explanation of the unitization effect, in terms of lateral masking. These results indicate that syllable onsets are processed as perceptual units by the reading system and that the unitization effect is position dependent.     

Whole-word units are used before orthographic knowledge in perceptual development

A visual search task for target letters in multiletter displays was used to investigate information-processing differences between college students and presecond-grade children (mean age = 7 years, 4 months). The stimulus displays consisted of single words, pronounceable pseudowords, and unpronounceable nonwords varying in length from three to five letters. The mean response times for indicating whether or not a target letter occurred in the display increased with the number of display letters for both groups, although there were apparent differences between groups in the rate of search and type of search strategy used. Pre-second-grade children responded faster to word displays than to pseudoword and nonword displays, indicating that familiar letter strings could be processed faster than unfamiliar strings regardless of whether or not the latter were consistent with rules of English orthography. In contrast, college students processed words and pseudowords about equally well, and both resulted in faster responses than nonwords. As reading skills develop, children apparently come to process familiar words differently from other letter strings. Only after a significant sightword vocabulary is established do children seem to recognize the regularities of standard English orthography and make use of this knowledge to facilitate perceptual processes.     

Perception of acoustic correlates of major phrasal units by young infants.

How might young learners parse speech into linguistically relevant units? Sensitivity to prosodic markers of these segments is one possibility. Seven experiments examined infants' sensitivity to acoustic correlates of phrasal units in English. The results suggest that: (a) 9 month olds, but not 6 month olds, are attuned to cues that differentially mark speech that is artificially segmented at linguistically COINCIDENT as opposed to NONCOINCIDENT boundaries (Experiments 1 and 2); (b) the pattern holds across both subject phrases and predicate phrases and across samples of both Child- and Adult-directed speech (Experiments 3, 4, and 7); and (c) both 9 month olds and adults show the sensitivity even when most phonetic information is removed by low-pass filtering (Experiments 5 and (6). Acoustic analyses suggest that pitch changes and in some cases durational changes are potential cues that infants might be using to make their discriminations. These findings are discussed with respect to their implications for theories of language acquisition.     

Time errors are perceptual

Summary Methods for the measurement of time-errors (TEs) in the comparison of successive stimulus magnitudes are discussed. Combining a Thurstonian scaling method with the assumption of a fixed subjective width of the equal category, independent of stimulus level, a ratio scale for subjective differences within pairs of successive stimuli is derived. In a tone duration comparison experiment, with the TE defined in the terms of these subjective duration differences, data from four experimental groups were compared, the groups using different modes of judging and responding. Only minor effects of this factor were found, and hence it is concluded that the TE is a true perceptual phenomenon rather than an effect of response bias, criterion bias, or mediating verbal responses to the absolute level of stimulation. The quantitative results are interpreted in terms of a general model for the comparison of successive stimuli, employing the concepts of adaptation and differential weighting of sensation magnitudes.This investigation was supported by grants to the author from the University of Stockholm and from the Swedish Office of Administrative Rationalization and Economy (for computer time), and by grants to Mats Björkman and Hannes Eisler from the Swedish Council for Social Science Research, whose free consultation service at the Department of Statistics, University of Stockholm, also benefited the author.     

The interplay between perceptual organization and categorization in the representation of complex visual patterns by young infants

The relation between perceptual organization and categorization processes in 3- and 4-month-olds was explored. The question was whether an invariant part abstracted during category learning could interfere with Gestalt organizational processes. A 2003 study by Quinn and Schyns had reported that an initial category familiarization experience in which infants were presented with visual patterns consisting of a pacman shape and a complex polygon could interfere with infants' subsequent good continuation-based parsing of a circle from visual patterns consisting of a circle and a complex polygon. However, an alternative noninterference explanation for the results was possible because the pacman had been presented with greater frequency and duration than had the circle. The current study repeated Quinn and Schyns's procedure but provided an equivalent number of familiarization trials and duration of study time for the infants to process the pacman during initial familiarization and the circle during subsequent familiarization. The results replicated the previous findings of Quinn and Schyns. The data are consistent with the interference account and suggest that a cognitive system of adaptable feature creation can take precedence over organizational principles with which a perceptual system comes pre-equipped.     

How infants use perceptual information to guide action

When infants catch a rolling ball by intercepting its trajectory, the action is prospectively controlled to take account of the object's speed, direction and path. We complicated this task in two ways: by occluding a portion of the ball's path with a screen, and by sometimes placing a barrier that blocked the ball's path behind the screen. In two experiments we manipulated visual information about the barrier and the ball's trajectory to see how this would aid 9‐month‐olds’ performance. Anticipatory reaching was possible but difficult with a partially occluded trajectory; actually catching the ball was aided by full view of the trajectory although timing of reach onset was not affected. Full sight of the barrier and trajectory through a transparent screen prevented inappropriate reaching, whereas sight of the barrier alone through a ‘window’ in an opaque screen did not. We interpreted these results as evidence for decreased performance as cognitive load increased with the loss of visual information. In contrast to anticipatory reaching behavior, search for the ball after it disappeared behind the screen was facilitated by the opaque window condition, confirming previous studies that found superior search with opaque versus transparent screens.     

Absolute and relative perceptual codes in young children

Three experiments were conducted to ascertain whether young children's perceptual codes, as evidenced by choice reaction times, were related to either the absolute difference or the ratio between stimuli. In Experiments 1 and 2, children were shown pairs of line lengths and were asked to choose either the longer or shorter line within each pair. In Experiment 3, children chose which of two birds on a map was closer to themselves or to the experimenter. In all three experiments, children's reaction times were related to both the absolute differences and ratios between pairs of stimuli. The findings suggest that perceptual judgments in young children may be based on both absolute and relational codes.     

A common perceptual parameter for stair climbing for children,young and old adults

In this paper we examine whether a common perceptual parameter is available for guiding old adults, young adults and children in climbing the highest stair mountable in a bipedal fashion. Previous works have shown that the ratio between the height of the stair and the hip height was the body-scaled invariance adopted as information for selecting the highest stair by young adults [Journal of Experimental Psychology: Human Perception and Performance 10 (1984) 683-703] but not by older adults [Journal of Experimental Psychology: Human Perception and Performance 3 (1992) 691-697]. Indeed, for older adults additional bio-mechanical parameters needed to be added to the model due to their decrease in leg strength and flexibility.Up to now, no perceptual invariant has been identified yet for determining the relevant information used for guiding the stair climbing action for normal healthy people. We propose a new parameter as the angle defined by the ratio between the height of the stair and the distance taken from the feet to the top edge of the stair before the initiation of the movement. We show that this angle is the same for children, young adults and older adults despite the different kinematics of the motion, the anthropometrics and the skill ability exhibit by the participants. In summary we show that even when the climbability judgments, based on the simple ratio leg length-stair height, are influenced by differences in age, participants use a common perceptual variable when they are coordinating their stair climbing action.     

Cognitive complexity effects in perceptual classification are dissociable

It has been proposed that a procedural-based classification system mediates the learning of information-integration categories, whereas a hypothesis-testing system mediates the learning of rule-based categories. Ashby, Ell and Waldron (2003) provided support for this claim by showing that a button switch introduced during classification transfer adversely affected information-integration but not rule-based performance. Nosofsky, Stanton and Zaki (2005) showed that increasing "cognitive complexity" can lead to button switch costs on rule-based performance. They argue that "cognitive complexity," and not the existence of separable classification systems, accounts for Ashby et al.'s empirical dissociation. The present study shows that experimental manipulations that increase "cognitive complexity" often have dissociable effects on information-integration and rule-based classification that are predicted a priori from the processing characteristics associated with the procedural-based and hypothesis-testing systems. These results suggest that manipulations of "cognitive complexity" can be dissociated, suggesting that "cognitive complexity" in not a unitary construct that affects a single psychological process.     

Pattern vision in young infants

The Psychological Record -     

Memory predictions are influenced by perceptual information: evidence for metacognitive illusions

Although perceptual information is utilized to judge size or depth, little work has investigated whether such information is used to make memory predictions. The present study examined how the font size of to-be-remembered words influences predicted memory performance. Participants studied words for a free-recall test that varied in font size and made judgments of learning (JOLs) for each item. JOLs were influenced by font size, as larger font sizes were given higher JOLs, whereas little relationship was evident between font size and recall. The effect was modified when other, more valid, sources of information (e.g., associative strength) were available when JOLs were made and persisted despite experience with multiple study-test sessions, use of a forgetting scale to assess predictions, and explicit warning of participants that font size has little effect on memory performance. When ease of reading was manipulated, such that large font size words were made less fluent, the effect was eliminated. Thus, highly accessible perceptual cues can strongly influence JOLs, likely via encoding fluency, and this effect can lead to metacognitive illusions     

The language environment of the young infant: implications for early perceptual development

The purpose of this article is to review recent research on the young infant's use of voice-specific as well as voice-nonspecific auditory information during early language processing, to suggest a possible mechanism that biases the young infant towards this information, and to discuss potential implications of the early saliency of this information for later language development. Auditory preferences expressed by young infants are of interest because they demonstrate which properties of complex auditory events are effective in capturing the infant's attention. Moreover, the presence of such auditory preferences has led to speculations about their possible origins in both pre- and postnatal auditory experience. Research examining the role of early auditory experience in the formation of preferences is presented, along with a discussion of how the constrained nature of early auditory experience (particularly prenatal) may bias the young infant towards specific features of maternal as well as nonmaternal speech.     

Dyslexic and typical-reading children use vowel digraphs as perceptual units in reading

Digraphs are graphemes that are composed of two letters like the “ou” in “soup”. We hypothesized that the serial-reading strategy of dyslexic readers might interfere with the processing of digraphs. We used a letter-detection task to compare the processing of vowel digraphs in dyslexic and typical-reading children. Both groups were found to be slower in detecting a letter within a vowel digraph than in detecting a letter of a single-letter grapheme. The slower response to target letters embedded in a digraph was position independent in both groups. We also found that dyslexic children did not differ from typical-reading children in the detection of letters in words. These results indicate that typical-reading and dyslexic children process vowel digraphs as perceptual units and that dyslexic children do not show impairments in this early visual process.     

Dyslexic and typical-reading children use vowel digraphs as perceptual units in reading

Digraphs are graphemes that are composed of two letters like the "ou" in "soup". We hypothesized that the serial-reading strategy of dyslexic readers might interfere with the processing of digraphs. We used a letter-detection task to compare the processing of vowel digraphs in dyslexic and typical-reading children. Both groups were found to be slower in detecting a letter within a vowel digraph than in detecting a letter of a single-letter grapheme. The slower response to target letters embedded in a digraph was position independent in both groups. We also found that dyslexic children did not differ from typical-reading children in the detection of letters in words. These results indicate that typical-reading and dyslexic children process vowel digraphs as perceptual units and that dyslexic children do not show impairments in this early visual process.     

Relationships between perceptual and conceptual mediational systems in young children

Children aged 48–77 months were afforded experience in either color oddity or nominal class sorting prior to a transfer task testing the ability to apply the oddity rule (“which one doesn't belong”) to three picture arrays where solution was based on nominal class membership. The youngest children in the sample did not benefit from either perceptual rule experience or nominal sorting experience. Subsequent age groups benefited first from the nominal sorting treatment, then from both perceptual rule and nominal sorting activities, and finally the older children did not require priming in either the perceptual or nominal domain for success on the transfer task.     

An investigation of young infants' perceptual representations of speech sounds

The present study examined the ability of newborns and 2-month-olds to detect phonetic differences between syllables. By relying on the modified high-amplitude sucking procedure, which did not permit the infants to use a simple same-different response, the present experiments tapped the perceptual representations of the speech sounds. Infants as young as a few days old displayed some capacity to represent differences in a set of syllables varying in their phonetic composition, although there was no convincing evidence that their representations were structured in terms of phonetic segments. Finally, evidence of developmental changes in speech processing were noted for the first time with infants in this age range. The change noted was a tendency from global toward more specific representations on the part of the older infants.     

What goes up may come down: perceptual process and knowledge access in the organization of complex visual patterns by young infants

The relationship between perceptual categorization and organization processes in 3‐ to 4‐month‐old infants was explored. The question was whether an invariant part abstracted during category learning could interfere with Gestalt organizational processes. Experiment 1 showed that the infants could parse a circle in accord with good continuation from visual patterns consisting of a circle and a complex polygon. In Experiments 2 and 3, however, this parsing was interfered with by a prior category familiarization experience in which infants were presented with visual patterns consisting of a pacman shape and a complex polygon. Part 1 of Experiments 2 and 3 showed that the infants recognized the pacman as familiar, and Part 2 demonstrated that the representation of the pacman blocked the subsequent parsing of the circle. The results suggest that a cognitive system of flexible feature creation can override organizational principles with which a perceptual system may come pre‐equipped.