Category typicality effects in children's memory performance: Qualitative and quantitative differences in the processing of category information

Kindergarten, third, and sixth graders (6, 9, and 12 years of age, respectively) received a cue-at-input/cue-at-output recall task, using category typical and atypical items that were based on either (1) children's conceptions of item typicality, or (2) adults' conceptions of item typicality. At each grade level, recall was greater with the child-defined lists than with the adult-defined lists, and typical items were recalled to a greater extent than atypical items. Further analyses items were recalled to a greater extent than atypical items. Further analyses revealed that the recall of typical items varied as a function of children's typicality ratings of items, and that the “typicality effect” in the adult-norm condition was due primarily to the childrennot realizing that many of the atypical items were appropriate category exemplars. In contrast, typicality effects in the child-norm condition were attributed to qualitative differences in the judged “goodness of example” of the typical and atypical items. The results were discussed in terms of the appropriateness of typicality as a dimension of children's natural language concepts, the role of age differences in knowledge base in affecting performance on a cognitive task, and of the importance of using child-generated norms in studies of children's processing of category information.     

Effect of typicality on online category verification of animate category exemplars in aphasia

Normal young, elderly, Broca's aphasic, and Wernicke's aphasic individuals participated in an online category verification task where primes were superordinate category labels while targets were either typical or atypical examples of animate categories or nonmembers belonging to inanimate categories. The reaction time to judge whether the target belonged to the preceding category label was measured. Results indicated that all four groups made significantly greater errors on atypical examples compared to typical examples. Young and elderly individuals, and Broca's aphasic patients performed similarly on the verification task; these groups demonstrated faster reaction times on typical examples than atypical examples. Wernicke's aphasic patients made the most errors on the task and were slowest to respond than any other participant group. Also, these participants were not significantly faster at accepting correct typical examples compared to correct atypical examples. The results from the four groups are discussed with relevance to prototype/family resemblance models of typicality.     

Infants' object category formation and use: Real-world context effects on category use in object processing

Three experiments investigated category formation based on real-world encounters with objects and how that category knowledge functioned as a top-down influence on infants' scene processing. 5-month-old infants received various experiences with exemplars of an object category and then were shown a display containing 2 adjacent novel objects, 1 of which was a novel exemplar of the category. If infants recognized this novel exemplar, they could use category information to determine the boundary between the 2 objects. Only infants who experienced object exemplars in situations that closely mimicked everyday infant experiences with objects successfully parsed the display. Results suggest that regularities in the contexts where infants experience similar objects help infants link their experiences and form object categories that can be used to segregate novel scenes. These results shed light on the real-world process of infant knowledge base formation and on how infants use their knowledge base to segment real-world scenes.     

A stereo advantage in generalizing over changes in viewpoint on object recognition tasks

In four experiments, we examined whether generalization to unfamiliar views was better under stereo viewing or under nonstereo viewing across different tasks and stimuli. In the first three experiments, we used a sequential matching task in which observers matched the identities of shaded tube-like objects. Across Experiments 1-3, we manipulated the presentation method of the nonstereo stimuli (having observers wear an eye patch vs. showing observers the same screen image) and the magnitude of the viewpoint change (30 degrees vs. 38 degrees). In Experiment 4, observers identified "easy" and "hard" rotating wire-frame objects at the individual level under stereo and nonstereo viewing conditions. We found a stereo advantage for generalizing to unfamiliar views in all the experiments. However, in these experiments, performance remained view dependent even under stereo viewing. These results strongly argue against strictly 2-D image-based models of object recognition, at least for the stimuli and recognition tasks used, and suggest that observers used representations that contained view-specific local depth information.     

An advantage for active versus passive aperture-viewing in visual object recognition

In aperture viewing the field-of-view is restricted, such that only a small part of an image is visible, enforcing serial exploration of different regions of an object in order to successfully recognise it. Previous studies have used either active control or passive observation of the viewing aperture, but have not contrasted the two modes. Active viewing has previously been shown to confer an advantage in visual object recognition. We displayed objects through a small moveable aperture and tested whether people's ability to identify the images as familiar or novel objects was influenced by how the window location was controlled. Participants recognised objects faster when they actively controlled the window using their finger on a touch-screen, as opposed to passively observing the moving window. There was no difference between passively viewing again one's own window movement as generated in a previous block of trials versus viewing window movements that had been generated by other participants. These results contrast with those from comparable studies of haptic object recognition, which have found a benefit for passive over active stimulus exploration, but accord with findings of an advantage of active viewing in visual object recognition.     

Perceptual differentiation as a source of category effects in object processing: Evidence from naming and object decision

The locus of category effects in picture recognition and naming was examined in two experiments with normal subjects. Subjects carried out object decision (deciding whether the stimulus is a “real” object or not) and naming tasks with pictures of clothing, furniture, fruit, and vegetables. These categories are distinguished by containing either relatively many exemplars with similar perceptual structures (fruit and vegetables;structurally similar categories), or relatively few exemplars with similar perceptual structures (clothing and furniture;structurally dissimilar categories). In Experiment 1, responses to the stimuli from the structurally similar categories were slower than responses to stimuli from the structurally dissimilar categories, and this effect was larger in the naming than in the object decision task. Further, prior object decisions to stimuli from structurally similar categories facilitated their subsequent naming. In Experiment 2, we orthogonally manipulated object decision and naming as prime and target tasks, again with stimuli from the four categories. Category effects, with responses slower to objects from structurally similar categories, were again larger in naming than in object decision, and these category effects in naming were reduced by priming with both naming and object decision. We interpret the data to indicate that category effects in object naming can reflect visually based competition which is reduced by the preactivation of stored structural knowledge for objects.     

Category specificity in normal episodic learning: applications to object recognition and category-specific agnosia

Studies of patients with category-specific agnosia (CSA) have given rise to multiple theories of object recognition, most of which assume the existence of a stable, abstract semantic memory system. We applied an episodic view of memory to questions raised by CSA in a series of studies examining normal observers' recall of newly learned attributes of familiar objects. Subjects first learned to associate arbitrarily assigned colors or textures to objects in a training phase, and then attempted to report the newly learned attribute of each object in a recall task. Our subjects' pattern of recall errors was similar both quantitatively and qualitatively to the identification deficits among patients with CSA for biological objects. Furthermore, errors tended to reflect conceptually and structurally based confusions. We suggest that object identification involves recruitment and integration of information across distributed episodic memories and that this process is susceptible to interference from objects that are structurally similar and conceptually related.     

Category typicality effects in episodic memory: Testing models of distinctiveness

Middle Tennessee State University, Murfreesboro, Tennessee Category typicality effects were investigated within the context of three models of distinctiveness: a univariate model, a fixed-multifeature model, and a weighted-multifeature model. High-typical, medium-typical, and atypical targets were embedded in lists containing a background set of mediumto high-typicality items. Atypical items were more poorly recalled than were medium- and high-typical items independently of list structure. In recognition, subjects who studied high-typical items had difficulty discriminating between high-typical items that were and were not presented as part of the list. However, item typicality had little effect on the recognition performance of subjects who did not study high-typical items. These findings were consistent with the weighted-multifeature model of distinctiveness.     

Functional neuroimaging studies of category specificity in object recognition: a critical review and meta-analysis

Functional neuroimaging studies in which the cortical organization for semantic knowledge has been addressed have revealed interesting dissociations in the recognition of different object categories, such as faces, natural objects, and manufactured objects. The present paper critically reviews these studies and performs a meta-analysis of stereotactic coordinates to determine whether category membership predicts patterns of brain activation across different studies. This meta-analysis revealed that, in the ventral temporal cortex, recognition of manufactured objects activates more medial aspects of the fusiform gyrus, as compared with natural object or face recognition. Face recognition activates more inferior aspects of the ventral temporal cortex, as compared with manufactured object recognition. The recognition task used—viewing, matching, or naming—also predicted brain activation patterns. Specifically, matching tasks recruit more inferior occipital regions than do either naming or viewing tasks, whereas naming tasks recruit more anterior ventral temporal sites than do either viewing or matching tasks. These findings indicate that the cognitive demands of a particular recognition task are as predictive of cortical activation patterns as is category membership.     

Impact of varying levels of expertise on decisions of category typicality

Experts on domains of basic level object categories possess extensive knowledge of features used to both individuate and categorize groups of similar members. Two studies were conducted to determine the impact of high knowledge on intermediate and advanced experts' typicality decisions for basic and subordinate level category exemplars, and to investigate whether the pattern of influence of factors (in particular, central tendency and subjective familiarity) remained fixed throughout the continuum of expertise. Example goodness increased as a function of the level of specificity of the category for which typicality was rated. Subjective familiarity was the principal determinant of typicality for individuals with high knowledge, whereas central tendency was related to typicality when knowledge was not particularly high. Advanced and intermediate experts produced similar ratings of typicality, indicating that individuals' decisions of typicality do not change markedly once intermediate levels of competency have been attained. The incorporation of knowledge effects into models of semantic memory, as well as interactions among knowledge, psychological factors, and environmental factors in determining typicality, are discussed.     

The roles of typicality, instance dominance, and category dominance in verifying category membership

Four experiments examined the relationships between category verification reaction time (RT), exemplar typicality, instance dominance, category selection time (an RT measure of category dominance), and three production measures of category dominance. The category dominance measures were obtained in two experiments for use in two nearly identical category verification experiments. In one category verification experiment, the category name was presented 800 ms before the exemplar name; in the other, the exemplar name preceded the category name by 800 ms. Multiple regression analyses of the yes and no category verification RTs indicated that category dominance produced large and highly significant effects in all conditions, whereas instance dominance produced marginally significant and selective effects. Typicality had no effect beyond its shared effect with the dominance measures except as a possible suppressor variable. Category selection time was the best predictor, although all of the category dominance measures were better predictors than typicality or instance dominance. It is concluded that typicality may be an inappropriate independent variable for RT tasks studying the memory representation of natural-world knowledge.     

View-invariant object category learning, recognition, and search: how spatial and object attention are coordinated using surface-based attentional shrouds

How does the brain learn to recognize an object from multiple viewpoints while scanning a scene with eye movements? How does the brain avoid the problem of erroneously classifying parts of different objects together? How are attention and eye movements intelligently coordinated to facilitate object learning? A neural model provides a unified mechanistic explanation of how spatial and object attention work together to search a scene and learn what is in it. The ARTSCAN model predicts how an object's surface representation generates a form-fitting distribution of spatial attention, or "attentional shroud". All surface representations dynamically compete for spatial attention to form a shroud. The winning shroud persists during active scanning of the object. The shroud maintains sustained activity of an emerging view-invariant category representation while multiple view-specific category representations are learned and are linked through associative learning to the view-invariant object category. The shroud also helps to restrict scanning eye movements to salient features on the attended object. Object attention plays a role in controlling and stabilizing the learning of view-specific object categories. Spatial attention hereby coordinates the deployment of object attention during object category learning. Shroud collapse releases a reset signal that inhibits the active view-invariant category in the What cortical processing stream. Then a new shroud, corresponding to a different object, forms in the Where cortical processing stream, and search using attention shifts and eye movements continues to learn new objects throughout a scene. The model mechanistically clarifies basic properties of attention shifts (engage, move, disengage) and inhibition of return. It simulates human reaction time data about object-based spatial attention shifts, and learns with 98.1% accuracy and a compression of 430 on a letter database whose letters vary in size, position, and orientation. The model provides a powerful framework for unifying many data about spatial and object attention, and their interactions during perception, cognition, and action.     

The representation of category typicality in the frontal cortex and its cross-linguistic variations

When asked to judge the membership of typical (e.g., car) vs. atypical (e.g., train) pictures of a category (e.g., vehicle), native English (N = 18) and native Chinese speakers (N = 18) showed distinctive patterns of brain activity despite showing similar behavioral responses. Moreover, these differences were mainly due to the amount and pervasiveness of category information linguistically embedded in the everyday names of the items in the respective languages, with important differences across languages in how pervasive category labels are embedded in item-level terms. Nonetheless, the left inferior frontal gyrus and the bilateral medial frontal gyrus are the most consistent neural correlates of category typicality that persist across languages and linguistic cues. These data together suggest that both cross- and within-language differences in the explicitness of category information have strong effects on the nature of categorization processes performed by the brain.     

Solving anagrams: Category priming and the differential availability of category solutions

An experiment was performed to test the hypothesis that the effect of category name priming on anagram solving varies with the strength of the relationship between the solution word and the priming category. Subjects solved anagrams of taxonomic category instances under primed or unprimed conditions. In the primed condition, the name of the taxonomic category from which the solution word was chosen was provided on each trial. Priming was shown to facilitate anagram solution and the extent of this facilitation was directly related to the instance dominance of the solution word in the priming category. The results were discussed in terms of current models of semantic memory.     

Influencesicture context on object recognition

The effect of sorrounding context on the recognition of objects from briefly presented pictures was investigated. Forty-eight undergraduates saw 100 msec displays of either line drawings containing several objects embedded in context or drawings of object arrays without background context. Following each exposure they were required to select from among four objects the one that had been contained in the picture. Presentation of objects in context aided recognition only when incorrect response alternatives were inconsistent with the picture context. The results suggest that context contributes to the construction of a general characterization of the pictures which provides expectancies regarding the identity of specific objects.     

Category label and response location shifts in category learning

The category shift literature suggests that rule-based classification, an important form of explicit learning, is mediated by two separate learned associations: a stimulus-to-label association that associates stimuli and category labels, and a label-to-response association that associates category labels and responses. Three experiments investigate whether information–integration classification, an important form of implicit learning, is also mediated by two separate learned associations. Participants were trained on a rule-based or an information–integration categorization task and then the association between stimulus and category label, or between category label and response location was altered. For rule-based categories, and in line with previous research, breaking the association between stimulus and category label caused more interference than breaking the association between category label and response location. However, no differences in recovery rate emerged. For information–integration categories, breaking the association between stimulus and category label caused more interference and led to greater recovery than breaking the association between category label and response location. These results provide evidence that information–integration category learning is mediated by separate stimulus-to-label and label-to-response associations. Implications for the neurobiological basis of these two learned associations are discussed.     

The relationship between category typicality and concept familiarity: Evidence from Spanish- and English-speaking monolinguals

We examined the relationship between an item’s familiarity and its category typicality, employing ratings obtained from Spanish- and English-speaking monolinguals living in southern Florida. In the first experiment, Spanish- and English-speaking monolinguals were asked to rate the prototypicality of instances of 12 common language categories. The correlations between the Spanish and English speakers’ rated item typicality indicated that the prototypicality gradients of the Spanish and English monolinguals were fairly discrepant for a number of categories. In the second experiment, we examined the degree to which these differences in cultural typicality could be accounted for by differences in rated cultural familiarity. It was predicted that, if familiarity plays a role in determining cultural differences in prototypicality, statistically controlling for the effects of cultural familiarity should result in higher interlingual typicality correlations. This should be true particularly for those categories for which there is a wide discrepancy in the typicality gradients for the two language groups. These predictions were confirmed. Consequently, we conclude that item familiarity is at least one variable influencing cultural differences in category typicality gradients.     

Recall-to-reject: The effect of category cues on false recognition

Four experiments examined the effect of category cueing on recall-to-reject, one of the central memory-editing mechanisms thought to prevent the occurrence of false memories. When category names were used as retrieval cues, the typically observed false recognition effect was eliminated for semantically associated distractors (Experiment 1a) and, moreover, a reduction in the absolute level of the false alarm rate was found for phonologically associated distractors (Experiment 2a). In addition to the old/new-recognition data, analyses using multinomial models support the interpretation that category cueing was successful in increasing the probability of recall-to-reject (Experiments 1b and 2b). The results are in line with dual-process theories of recognition memory and provide further evidence for recall-to-reject in single item recognition. They demonstrate its potential to reduce false recognition even when explicit instructions are not given. In addition, the results demonstrate that the paradigm can give rise to side effects that oppose recall-to-reject. A simultaneous familiarity increase can explain why many studies failed to find evidence for recall-to-reject in terms of false alarm rates.     

Indirect object recognition: evidence for associative processes in recognition memory

Rats' exploration of stimulus P (e.g., a domestic object) is reduced following either its direct exposure or its indirect exposure and is taken to indicate recognition memory. Procedures for demonstrating indirect object recognition involve an initial presentation of object P with stimulus X (and of an object Q with stimulus Y). On test, stimulus X is presented with objects P and Q and rats' exploration of Q exceeds their exploration of P. One interpretation here is that the presentation of stimulus X on test associatively activates the memory of object P, which diminishes exploration of P relative to Q. It is possible, instead, that performance is simply the result of a novel pattern of stimulation generated by the unfamiliar combination of X and Q. The authors modified this procedure to reduce the likelihood of such a process. Their procedure involved first the presentation of PX and QY before the presentation of stimulus X alone. During the test that followed, objects P and Q were presented but stimulus X was removed. The authors found that exploration of Q remained greater than that of P despite these modifications and discuss some theoretical implications of indirect, associative processes in recognition memory.