Perceptual learning in visual category acquisition

The attribute structure of a set of dot patterns was studied by having subjects segment (parse) the dots of each pattern into parts or subunits by drawing circles around groups of dots from each pattern. These parsing data were obtained for subjects who had no prior experience with the patterns and for subjects who had previously learned to identify the patterns as members of one of four categories. Analyses of the parsing data indicated that category learning increased the salience of large subunits that were similar in orientation for patterns that were members of the same category. This evidence for perceptual learning was obtained even when the category training procedure required learning to identify the patterns individually, suggesting that attribute abstraction and item learning are not incompatible. It was also obtained without an increase in overall intersubject agreement. The latter result led us to question the usefulness of intersubject agreement as an index of category knowledge.     

实物形状的知觉相似性对视觉隐喻加工的影响

视觉隐喻是众多研究者比较关注的领域, 当前多以物体简笔画、漫画及广告等方面的研究为主, 但对与生活密切相关的实物的视觉隐喻研究甚少。因此研究采用掩蔽启动范式、李克特9点量表及语音生成等研究方法, 在物体概念类型(概念相同、概念相异)及形状类型(形状相似、形状相异)条件下, 针对实物图片的形状知觉相似性是否对视觉隐喻加工产生影响进行探讨。结果发现无论物体概念是否相同, 形状相似性对个体的物体识别具有“促进”作用, 并有利于视觉隐喻加工; 在物体识别中, 当两个物体概念不同时, 个体会试图建立一个特设类别来对形状相似的物体进行归类, 从而实现了视觉隐喻的加工。因此研究进一步证明了实物形状的知觉相似性有利于视觉隐喻的加工。     

Central tendencies, extreme points, and prototype enhancement effects in ill-defined perceptual categorization

In three perceptual classification experiments involving ill-defined category structures, extreme prototype enhancement effects were observed in which prototypes were classified more accurately than other category instances. Such empirical findings can prove theoretically challenging to exemplar-based models of categorization if prototypes are psychological central tendencies of category instances. We found instead that category prototypes were sometimes better characterized as psychological extreme points relative to contrast categories. Extending a classic and widely cited study (Posner & Keele, 1968), participants learned categories created from distortions of dot patterns arranged in familiar shapes. Participants then made pairwise similarity judgements of the patterns. Multidimensional scaling (MDS) analyses of the similarity data revealed the prototypes to be psychological extreme points, not central tendencies. Evidence for extreme point representations was also found for novel prototype patterns displaying a symmetry structure and for prototypes of grid patterns used in recent studies by McLaren and colleagues (McLaren, Bennet, Guttman-Nahir, Kim, & M ackintosh, 1995). When used in combination with the derived M DS solutions, an exemplar-based model of categorization, the Generalized Context Model (Nosofsky, 1986), provided good fits to the observed categorization data in all three experiments.     

Testing the speech unit hypothesis with the primed matching task: Phoneme categories are perceptually basic

The basic speech unit (phoneme or syllable) problem was investigatedwith the primed matching task. In primed matching, subjects have to decide whether the elements of stimulus pairs are the same or different. The prime should facilitate matching in as far as its representation is similar to the stimuli to be matched. If stimulus representations generate graded structure, with stimulus instances being more or less prototypical for the category, priming should interact with prototypicality because prototypical instances are more similar to the activated category than are low-prototypical instances. Rosch (1975a, 1975b) showed that, by varying the matching criterion (matching for physical identity or for belonging to the same category), the specific patterns of the priming × prototypicality interaction could differentiate perceptually based from abstract categories. Bytesting this pattern forphoneme and syllable categories, the abstraction level of these categories canbe studied. After finding reliable prototypicality effects for both phoneme and syllable categories (Experiments 1 and 2), primed phoneme matching (Experiments 3 and 4) and primed syllable matching (Experiments 5 and 6) were used under both physical identity instructions and same-category instructions. The results make clear that phoneme categories are represented on the basis of perceptual information, whereas syllable representations are more abstract. The phoneme category can thus be identified as the basic speech unit. Implications for phoneme and syllable representation are discussed.     

Objects, parts, and categories

Concepts may be organized into taxonomies varying in inclusiveness or abstraction, such as furniture, table, card table or animal, bird, robin. For taxonomies of common objects and organisms, the basic level, the level of table and bird, has been determined to be most informative (Rosch, Mervis, Gray, Johnson, & Boyes-Braem, 1976). Psychology, linguistics, and anthropology have produced a variety of measures of perception, behavior, and communication that converge on the basic level. Here, we present data showing that the basic level differs qualitatively from other levels in taxonomies of objects and of living things and present an explanation for why so many measures converge at that level. We have found that part terms proliferate in subjects' listings of attributes characterizing category members at the basic level, but are rarely listed at a general level. At a more specific level, fewer parts are listed, though more are judged to be true. Basic level objects are distinguished from one another by parts, but members of subordinate categories share parts and differ from one another on other attributes. Informants agree on the parts of objects, and also on relative "goodness" of the various parts. Perceptual salience and functional significance both appear to contribute to perceived part goodness. Names of parts frequently enjoy a duality not evident in names of other attributes; they refer at once to a particular appearance and to a particular function. We propose that part configuration underlies the various empirical operations of perception, behavior, and communication that converge at the basic level. Part configuration underlies the perceptual measures because it determines the shapes of objects to a large degree. Parts underlie the behavioral tasks because most of our behaviors is indirect toward parts of objects. Labeling appears to follow the natural breaks of perception and behavior; consequently, part configuration also underlies communication measures. Because elements of more abstract taxonomies, such as scenes and events, can also be decomposed into parts, this analysis provides a bridge to organization in other domains of knowledge. Knowledge organization by parts (partonomy) is contrasted to organization by kinds (taxonomy). Taxonomies serve to organize numerous classes of entities and to allow inference from larger sets to sets included in them. Partonomies serve to separate entities into their structural components and to organize knowledge of function by components of structure. The informativeness of the basic level may originate from the availability of inference from structure to function at that level.     

Categorization by schema relations and perceptual similarity in 5-year-olds and adults: A study in vision and in audition

This research explores the way in which young children (5 years of age) and adults use perceptual and conceptual cues for categorizing objects processed by vision or by audition. Three experiments were carried out using forced-choice categorization tasks that allowed responses based on taxonomic relations (e.g., vehicles) or on schema category relations (e.g., vehicles that can be seen on the road). In Experiment 1 (visual modality), prominent responses based on conceptually close objects (e.g., objects included in a schema category) were observed. These responses were also favored when within-category objects were perceptually similar. In Experiment 2 (auditory modality), schema category responses depended on age and were influenced by both within- and between-category perceptual similarity relations. Experiment 3 examined whether these results could be explained in terms of sensory modality specializations or rather in terms of information processing constraints (sequential vs. simultaneous processing).     

The effects of perceptual similarity and category membership on early word-referent identification

We investigated the impact of perceptual and categorical relatedness between a target and a distracter object on early referent identification in infants and adults. In an intermodal preferential looking (IPL) task, participants looked at a target object paired with a distracter object that could be perceptually similar or dissimilar and drawn from the same or different global category. The proportion of target looking measures revealed that infants and adults were sensitive to the interplay between category membership and perceptual similarity. Online latency measures demonstrated an advantage for perceptually dissimilar items regardless of their categorical status, indicating that different IPL measures index different processes during target identification. Results suggest that perceptual similarity and category membership of the objects lead to competition effects in word recognition and referent identification in both adults and infants and that lexical categorization and nonlinguistic categorization processes are closely related during infancy.     

Discrimination and categorization of photographs of natural objects by chimpanzees (Pan troglodytes)

Two experiments assessed the ability of four adult female chimpanzees to categorize natural objects. Chimpanzees were initially trained to match different color photographs of familiar objects from four possible categories. In training, all the comparison stimuli were from the same category in one condition, and from different categories in another condition. For all subjects, training performance was consistently better for the "different category" than for the "same category" trials. Probe trials were shown after training. In probe trials, the sample and positive comparison stimuli were different items from the same category, and the foils were selected from among the three other test categories. Individual performance was above chance in probe trials, suggesting that categorization by chimpanzees may transcend perceptual resemblance. These results were later replicated with novel stimulus items from the same four categories (experiment 2). Altogether, this research demonstrates that chimpanzees grouped perceptually different exemplars within the same category, and further suggests that these animals formed conceptual representations of the categories. Accepted after revision: 10 August 2001 Electronic Publication     

Atypical categorization in children with high-functioning autism spectrum disorder

Children with autism spectrum disorder process many perceptual and social events differently from typically developing children, suggesting that they may also form and recognize categories differently. We used a dot pattern categorization task and prototype comparison modeling to compare categorical processing in children with high-functioning autism spectrum disorder and matched typical controls. We were interested in whether there were differences in how children with autism use average similarity information about a category to make decisions. During testing, the group with autism spectrum disorder endorsed prototypes less and was seemingly less sensitive to differences between to-be-categorized items and the prototype. The findings suggest that individuals with high-functioning autism spectrum disorder are less likely to use overall average similarity when forming categories or making categorical decisions. Such differences in category formation and use may negatively impact processing of socially relevant information, such as facial expressions. A supplemental appendix for this article may be downloaded from http://pbr.psychonomic-journals.org/content/supplemental.     

The differing roles of comparison and contrast in children’s categorization

Comparison of perceptually similar exemplars from an object category encourages children to overlook compelling perceptual similarities and use relational and functional properties more relevant for taxonomic categorization. This article investigates whether showing children a contrasting object that is perceptually similar but out of kind serves the same function as comparison in heightening children’s attention to taxonomically relevant features. In this study, 4-year-olds completed a forced-choice categorization task in which they viewed exemplars from a target category and then selected among (a) a perceptually similar out-of-kind object, (b) a category member that differed perceptually from the exemplars, and (c) a thematically related object. Children were assigned to one of four conditions: No-Compare/No-Contrast, Compare/No-Contrast, No-Compare/Contrast, or Compare/Contrast. As in previous work, comparison increased the frequency of category responses, but there was no effect of contrast on categorization. However, only those in the Compare/Contrast condition displayed consistently taxonomic patterns of responding. Follow-up studies revealed that the effect of comparison plus contrast was evident only when comparison preceded, rather than followed, contrast information and that the value added by providing contrastive information is not attributable to the perceptual similarity between the category exemplars and the contrast object. Comparison and contrast make differing contributions to children’s categorization.     

Measuring the influence of similarity on category-specific effects

There is evidence for both advantages and disadvantages in normal recognition of living over nonliving things. This paradox has been attributed to high levels of perceptual similarity within living categories having a different effect on performance in different contexts. However, since living things are intrinsically more similar to each other, previous studies could not determine whether the various category effects were due to perceptual similarity, or to other characteristics of living things. We used novel animal and vehicle stimuli that were matched for similarity to measure the influence of perceptual similarity in different contexts. We found that displaying highly similar objects in blocked sets reduced their perceived similarity, eliminating the detrimental effect on naming performance. Experiment 1 demonstrated a disadvantage for highly similar objects in name learning and name verification using mixed groups of similar and dissimilar animals and vehicles. Experiment 2 demonstrated no disadvantage for the same highly similar objects when they were blocked, e.g., similar animals presented alone. Thus, perceptual similarity, rather than other characteristics particular to living things, is affected by context, and could create apparent category effects under certain testing conditions.     

Hierarchical categorization by bilingual Latino children: does a basic-level bias exist?

Research has shown that children classify most easily at the basic level where objects in the same category look similar enough to each other to be grouped together but are distinct enough from objects in other categories to be discriminated (e.g., animal/bird/duck). In this article, the authors report on 2 experiments they conducted to determine whether children maintain this basic category bias when the perceptual similarity of stimuli at different hierarchical levels is equalized. Pictures within and across 3 hierarchical levels were made perceptually equivalent and shown to 71 Latino children who were bilingual in Spanish and English. In Experiment 1, the pictures used as exemplars could be categorized on any of the 3 hierarchical levels. In Experiment 2, example pictures unambiguously defined the level of categorization that would be accurate, and linguistic cues were given that might assist in the selection of the correct category. In both experiments, the children sorted pictures from all 3 levels equally well, but they found it harder to justify their sorting of superordinate pictures. English competence predicted sorting on the more ambiguous sorting task in Experiment 1; and English competence predicted verbal justifications in both experiments, even though the experiments were conducted in Spanish. Competence in Spanish or English was an equally good predictor of sorting in the better defined sorting task in Experiment 2. These findings indicate that a superordinate level deficiency remains after perceptual differences are eliminated and that the deficiency is cognitive in nature. Differences in the performances of children who differed in bilingualism support the hypothesis that a threshold of proficiency in both languages is an important determinant of the effect of bilingualism on categorization.     

Parts in object concepts: Experiments with artificial categories

Previous research has demonstrated that basic-level categories are associated with the parts of objects. Five experiments were conducted to investigate whether this correlation is caused by a psychological principle that requires basic concepts to have common parts. This hypothesis was investigated in the experiments by separating part and nonpart information in artificial categories. Basic-level structure was measured in two ways: as the level with the highest ratio of within-category similarity to between-category similarity, and as the level with the fastest categorization time in an object-identification task. The results revealed that basic-level structure could be found in categories that did not have parts in common. Furthermore, nonpart information, such as size, color, and texture, could both enhance the basic level and eliminate the basic-level advantage, depending on whether the nonpart information was consistent with or contradicted the part information. These results suggest that, psychologically, parts are neither necessary nor sufficient to form a basic level.     

Statistical learning of adjacent and nonadjacent dependencies among nonlinguistic sounds

Previous work has demonstrated that adults are capable of learning patterned relationships among adjacent syllables or tones in continuous sequences but not among nonadjacent syllables. However, adults are capable of learning patterned relationships among nonadjacent elements (segments or tones) if those elements are perceptually similar. The present study significantly broadens the scope of this previous work by demonstrating that adults are capable of encoding the same types of structure among unfamiliar nonlinguistic and nonmusical elements but only after much more extensive exposure. We presented participants with continuous streams of nonlinguistic noises and tested their ability to recognize patterned relationships. Participants learned the patterns among noises within adjacent groups but not within nonadjacent groups unless a perceptual similarity cue was added. This result provides evidence both that statistical learning mechanisms empower adults to extract structure from nonlinguistic and nonmusical elements and that perceptual similarity eases constraints on nonadjacent pattern learning. Supplemental materials for this article can be downloaded from pbr.psychonomic-journals.org/content/supplemental.     

Area and contrast effects upon perceptual and imagery acuity

We measured the size of visual fields within which actual and imagined circular patterns could be resolved, as the patterns varied in both area and relative contrast. As pattern area increased, imagery fields increased in size at the same rate as perceptual fields. However, as the relative contrast between parts of the patterns was reduced, perceptual fields diminished in size, while imagery fields did not. for all variations of pattern area and contrast, fields in imagery were roughly the same shape as fields in perception. A control experiment provided no support for the possible criticism that these results might be explained on the basis of subjects' expectations for the size and shape of the imagery fields, especially since control subjects falsely believed that reductions in contrast would reduce considerably the size of these fields. Although these findings suggest that images and physical objects are functionally equivalent at pattern-processing levels of the visual system, they demonstrate that images and objects are not functionally equivalent at certain levels of the visual system where information about relative contrast is processed.     

Children's perceptual organisation of hierarchical visual patterns

Abstract

Children's perceptual organisation of hierarchical patterns was investigated in two experiments through similarity judgements. Previous studies with adults demonstrated that the perceptual relations between the global configuration and the local elements of such patterns depend critically on the number of elements embedded in the pattern: Patterns composed of a few, relatively large elements are perceived in terms of global form and figural parts, whereas patterns composed of many relatively small elements are perceived in terms of global form and texture. In Experiment 1 children at three levels of age (preschoolers, first and third graders) were presented with a standard figure and two comparison figures—a proportional and an un proportional enlargement of the standard. The number of elements in the standard figure was varied. When the number of elements was small, children at all age levels concerned judged the proportional enlargement which preserves the global and local forms as well as the relationship between them as more similar. When the number of elements in the standard figure increased, children switched their preference to the un proportional enlargement which preserves both the global form and the textural properties of the standard figure. When the global configuration and the local elements were pitted against each other (Experiment 2), and the number of elements was rather large, preschoolers and third graders judged the comparison figure having the same global configuration as the standard but composed of different elements as more similar to the standard than the comparison figure having the same elements arranged in a different configuration. Overall, these results are similar to the ones obtained with adults: As far as the perceptual organisation of hierarchical patterns changes as a function of the number of elements for the adult perceiver, it changes also for the young child. These results do not support the hypothesis that young children perceive complex visual stimuli as undifferentiated wholes, as some develop mental researchers have proposed. Furthermore, the finding that for children, as for adults, the elements do not function perceptually as parts when the number of elements is large, implies that fewclement patterns are better candidates for testing hypotheses about the relative priority of wholes and parts across development.     

Comparison in the Development of Categories

Recent research on children's word learning has led to a paradox. Although word learning appears to be a deep source of insight into conceptual knowledge for children, preschoolers often categorize objects on the basis of shallow perceptual features such as shape. The current studies seek to resolve this discrepancy. We suggest that comparing multiple instances of a category enables children to extract deeper relational commonalities among category members. We examine 4-year-olds' categorization behaviors when asked to select a match for a target object (e.g., an apple) between a perceptually similar, out-of-kind object (e.g., a balloon) and a perceptually different category match (e.g., a banana). Children who learn a novel word as a label for multiple instances of the category are more likely to select the category match over the perceptual match. Children who learn a label for only one instance are equally likely to select either alternative. This effect is present even when individual target instances are more perceptually similar to the perceptual choice than to the category choice. We conclude that structural alignment processes may be important in the development of category understanding.     

The role of the structure of parts and of the overall object shape in children's generalization of novel object names

We investigated the role of the structure of stimuli and their functional affordance on novel name generalization. Three- and 5-year-old children and adults were shown a training object with two possible functions, each one associated with a different part. They were taught about the name and the function of the object. We compared the classifications obtained for transfer stimuli composed of one part of the training stimulus—functional or not, perceptually transformed or not, or composed of all the original training parts. Even young children generalized the novel name to functional one-part transfer objects and disregarded non-functional or dysfunctional objects, although their generalizations were more constrained by perceptual similarity than that of the adults.     

The flexible use of inductive and geometric spatial categories

The present study examined the flexibility with which people can adopt different category schemes in the spatial domain. In a location memory task, participants viewed and estimated the locations of four kinds of objects that were spatially grouped by object identity. This identity-based arrangement was either congruent or incongruent with the perceptually based, geometric categories that have been reported in previous research. Four experiments examined the conditions under which these different category schemes are used to inform estimates of locations. The results showed that use of identity information depended on the number of objects to be remembered during a trial: When one or two objects were remembered at a time, only geometric categories affected estimates, but when four objects were to be remembered, both geometric categories and identity groupings affected estimates. As memory load increases, participants rely on additional sources to inform their estimates of location.     

Category structure affects the developmental trajectory of children's inductive inferences for both natural kinds and artefacts

Inductive reasoning is fundamental to human cognition, yet it remains unclear how we develop this ability and what might influence our inductive choices. We created novel categories in which crucial factors such as domain and category structure were manipulated orthogonally. We trained 403 4–9-year-old children to categorise well-matched natural kind and artefact stimuli with either featural or relational category structure, followed by induction tasks. This wide age range allowed for the first full exploration of the developmental trajectory of inductive reasoning in both domains. We found a gradual transition from perceptual to categorical induction with age. This pattern was stable across domains, but interestingly, children showed a category bias one year later for relational categories. We hypothesise that the ability to use category information in inductive reasoning develops gradually, but is delayed when children need to process and apply more complex category structures.