Understanding Categorical Hierarchies: The Earliest Levels of Skill

2 categorization skills necessary for understanding hierarchies are the ability to form categories at different levels of generality and the ability to include the same objects into multiple categories. 2-year-olds appear to have the first skill, but some theoretical and empirical work suggests that the second may be a later acquisition. Yet, in 3 studies, 2- and 3-year-olds applied familiar basic level and superordinate labels to the same objects, even when reminded of basic labels before being tested with superordinates. They did not reserve superordinates for objects with unfamiliar basic level names (Study 2), and they were willing to apply superordinates to objects presented singly rather than in groups (Study 3). Thus, contrary to the implications of some previous work, 2- and 3-year-olds appear to have both of the categorization skills necessary for forming categorical hierarchies.     

Reinstatement of postresponse stimuli prior to reward in delayed-reward discrimination learning by pigeons

Delayed-reward learning in pigeons was examined using a simultaneous red-green visual discrimination task in which the conditions during the delay interval were varied between groups. The nondifferential group received training in which the stimulus present during the 1-min delay was the same following a peck on the correct and incorrect colors. The other three groups received 1-min delay training in which different stimuli occurred in the delay interval following correct and incorrect choices. The differential group received continuous, differential stimuli during the delay. The reinstatement group received the differential stimuli in the 10 sec immediately following the choice and during the last 10 sec of the delay. The reversedcue group was treated in the same way, except that the 10-sec delay stimulus immediately following an incorrect response was also presented for 10 sec prior to reward on correct choices, and the stimulus following a correct response also occurred 10 sec before nonreward on incorrect choices. Nondifferential birds failed to learn the discrimination, while differential and reinstatement birds learned it readily. The reversed-cue birds learned to choose the incorrect stimulus. Differential and reinstatement birds showed no decrement in performance when the delay was increased to 2 min. These findings suggest that similarity of prereward and postresponse delay stimuli controls choice responding in long-delay learning, a finding compatible with both memorial and conditioned reinforcement interpretations.     

Availability and spontaneous use of verbal labels in sorting categorization by 16–23-month olds

This study investigated the role of word knowledge and spontaneous labeling of familiar objects in free sorting object categorization by 16–23-month-old children. General vocabulary was related to categorization on particular tasks involving both familiar and unfamiliar objects. Object labeling was associated with categorization when familiar objects of a given kind were identical. Spontaneous object labeling was also the only predictor of non-familiar object categorization, beyond the effects of age and vocabulary. The pattern of results suggests that spontaneous object labeling during free sorting is a reflection of the child's heightened involvement in the challenge of category discovery, thus perhaps facilitating object categorization. The findings reinforce the importance of teachers engaging toddlers in interactive object naming and world learning, as well as encouraging self-narration.     

Representation strength in pigeon short-term memory: Effect of delay training

An attempt was madeto manipulate the strength of internal stimulus representations by exposing pigeons to brief delays between sample offset and comparison onset in a delayed conditional discrimination. In Experiment 1, pigeons were first trained on delayed conditional discrimination with either short (0.5-sec) delays or no delays. When delays were increased by 2.0 sec, birds trained with a delay performed at a higher level than did birds trained with no delays. In Experiment 2, subjects were first trained on a delayed simple discrimination. Following a circle stimulus, responses to a white key were reinforced; however, following a dot stimulus, responses to the white key were not reinforced. The pigeons were then trained on a delayed conditional discrimination involving hue samples and line-orientation comparisons with differential outcomes. Choice of vertical following red yielded food; choice of horizontal following green yielded no food. Mixed delays were then introduced to birds in Group Delay, whereas birds in the control group received overtraining. When tested on a delayed simple discrimination with hue stimuli (red and green initial stimuli followed by white response stimulus), pigeons in Group Delay tended to perform at a higher level than did birds in the control group (i.e., although the birds in both groups responded more following red than following green, birds in Group Delay did this to a greater extent than did birds in the control group). Thus, experience with delays appears to strengthen stimulus representations established during training.     

Informational properties of infinite numbers of objects in concurrent discriminations by monkeys

Eight rhesus monkeys were trained on a counterbalanced series of concurrent, two-choice, discrimination tasks that provided different numbers of correct or incorrect objects as lists of discriminanda. Small, large, or infinite lengths of correct or incorrect object lists were combined in different tasks, and acquisition performances were compared. When tasks had an infinite number of objects in their correct list and a small number (4) in their incorrect list, acquisition entailed significantly less error than was seen when a small number of correct objects was paired with an infinite incorrect list. This pattern of outcomes seemed attributable to novelty preference. However, comparison of error distributions from tasks with infinite. list lengths to distributions from analogous tasks with fixed list lengths provided some basis for interpreting the way monkeys integrated information that emerged from the temporally discriminative properties of the tasks. One prospective concern was whether or not these performances represented behaviors like those seen in human cognitive discriminations of frequency of occurrence.     

Categorization and Naming: Basic-Level Sorting in Eighteen-Month-Olds and Its Relation to Language

2 studies investigate whether 18-month-old children spontaneously sort objects into basic-level categories, and how this ability is related to naming. In Study 1, 18-month-old children were given spontaneous sorting tasks, involving both identical objects and objects with basic-level intracategory variation. Children were scored as having passed the tasks if they produced "exhaustive grouping," that is, physically grouped all the objects of one kind into one location and the objects of the other kind into a different location. The children also received means-ends and object-permanence tasks. Children's parents received a checklist of early names. Children who produced exhaustive grouping used significantly more names than those who did not, in both identical and basic-level cases. There was no such relation between object-permanence and naming or between means-ends performance and naming. In Study 2, children received arrays of the same objects, with either identical objects or objects with basic-level variation in each group. No significant differences were found between the identical and basic-level tasks. However, as in the previous task, performance on both types of categorization was related to naming. Children who produced exhaustive grouping were reported to produce more names than those who did not. There appears to be a close relation between object categorization and naming in young children. The theoretical implications of this empirical association are discussed.     

The Dynamics of Preschoolers' Categorization Choices

The present research explored the effects of stimulus and task factors on preschoolers' (Experiments 1 and 3) and adults' (Experiment 2) tendency to categorize according to taxonomic relations, when those relations conflict with appearances. In Experiment 1, we examined the effects of and interactions among ( a ) available information, operationalized by using more- or less-informative stimulus types (objects vs. line drawings) and by the presence or absence of labeling, and ( b ) task constraints, operationalized by comparing sorting questions with inductive inferences questions. When provided with information that constrained the categorization decision, either through the availability of labels or a combination of enhanced physical informativeness of objects and an inference question, preschoolers reliably based their categorization decisions on taxonomic relations between physically dissimilar items. In Experiment 2, stimulus type (objects vs. line drawings) was shown to have a similar effect on adults. In Experiment 3, we examined the effects of stimulus type on preschoolers' inductive inferences and accuracy of naming. The effects in the two tasks were closely related, suggesting that the amount of available information affects different responses in similar ways. These data demonstrate the interactive effects of available information and task constraints on categorization decisions.     

Using the onto-semiotic approach to identify and analyze mathematical meaning when transiting between different coordinate systems in a multivariate context

The main objective of this paper is to apply the onto-semiotic approach to analyze the mathematical concept of different coordinate systems, as well as some situations and university students’ actions related to these coordinate systems. The identification of objects that emerge from the mathematical activity and a first intent to describe an epistemic network that relates to this activity were carried out. Multivariate calculus students’ responses to questions involving single and multivariate functions in polar, cylindrical, and spherical coordinates were used to classify semiotic functions that relate the different mathematical objects.     

The effects of sodium pentobarbital on matching and oddity performance in pigeons

The effects of sodium pentobarbital on matching and oddity performance in pigeons were examined by employing a higher-order conditional discrimination paradigm. In this paradigm, the line orientation which was superimposed on all of the response keys signaled whether a response to the matching color or a response to the nonmatching color was correct. All pigeons had extensive previous training in this paradigm and were tested at each of three dosage levels: 5, 7.5, and 10 mg/kg. For all birds, a clear dose-related decrease in accuracy was observed; however, the effect was not differential for matching and oddity trials. Accuracy reductions were accompanied by an increase in position preference on both types of trials. The data are compatible with recent claims that physical identity of the sample and correct comparison stimulus need have no special status for pigeons.     

Interocular transfer in pigeons of color discrimination but not motor response training

Adult pigeons with one eye covered were trained to peck a response key using grain as a reinforcer. In subsequent tests, with the trained eye covered and the control eye open, the birds failed to peck the key. The subjects were then divided into two groups for a second experiment. The first group was trained on a single-key, peck/no-peck color discrimination task with the original control eye covered. When tested for interocular transfer of discrimination performance, these birds failed to respond at all. They were then trained to peck a blank response key with the training eye covered and the control eye open. Control-eye tests after this motor response training resulted in excellent transfer of color discrimination performance. The second group of subjects was trained to peck a blank key with first one eye covered and then the other, before monocular discrimination training was begun. These birds showed excellent transfer of discrimination performance during control-eye tests. These results show that, at least in the operant paradigm, motor response training does not transfer interocularly and this lack of transfer may interfere with transfer of discrimination performance.     

Six-month-old infants' categorization of containment spatial relations

Six-month-old infants' ability to form an abstract category of containment was examined using a standard infant categorization task. Infants were habituated to 4 pairs of objects in a containment relation. Following habituation, infants were tested with a novel example of the familiar containment relation and an example of an unfamiliar relation. Results indicate that infants look reliably longer at the unfamiliar versus familiar relation, indicating that they can form a categorical representation of containment. A second experiment demonstrated that infants do not rely on object occlusion to discriminate containment from a support or a behind spatial relation. Together, the results indicate that by 6 months, infants can recognize a containment relation from different angles and across different pairs of objects.     

Novelty and functional equivalence in superordinate categorization by pigeons

Superordinate categorization via association with a common response was studied in pigeons. Original training paired disparate classes (e.g., people + chairs and cars + flowers) with a common response (Responses 1 and 2, respectively). Reassignment training taught new responses (Responses 3 and 4, respectively) to one component class from each pair (e.g., people and cars). Superordinate categorization was documented in testing when the pigeons made the same responses to the stimuli that were withheld in reassignment training (e.g., chairs and flowers) as they did to the reassigned stimuli themselves (e.g., people and cars) and when the birds transferred these discriminative responses to novel stimuli from all four component classes. Reassignment training with novel stimuli produced effects that were similar to those of reassignment training with familiar stimuli. Superordinate categorization via association with a common response is thus a robust effect that generalizes to novel stimuli from each of the component classes.     

Understanding Category Members as "the Same Sort of Thing": Explicit Categorization in Ten-Month Infants

Although it is often acknowledged that classification exists in the first year of life, it has been suggested that infants are capable only of implicit categorization, recognizing that something is or is not familiar. In contrast, older children are thought to compare the stimuli or objects they categorize and to explicitly equate different category members. 2 habituation experiments were conducted in an attempt to determine whether 10-month-old infants are capable of explicit categorization. The approach taken was to insert nonmembers into the familiarization sequence in a categorization task. The nonmembers were designed so as to have a predictable effect on infants' performance whether or not these stimuli were included as infants processed the categorical information. The results suggest that infants do explicitly equate category members. Infants appeared to disregard the nonmembers in the familiarization sequence, basing their categorization response instead on the set of instances that were "the same sort of thing."     

Categorization and Its Developmental Relation to Early Language

Three studies examine the developmental relation between early linguistic and cognitive achievements. Studies 1 and 2 attempt to replicate previous findings of a strong temporal link between the ages at there is a sharp rise in new nominal productions and the appearance of 2-category grouping using a longitudinal design. Studies 1 and 2 differ principally in whether the same stimuli were employed each time the children's categorization was tested or whether different stimuli were employed. Study 3 compares the categorization performance of children identified as late talkers to age-matched and language-matched controls cross-sectionally. Our findings consistently show that children's ability to classify objects in a spatial of temporal order is independent of advances in productive vocabulary growth. These results suggest that although children's developing knowledge of object categories may underlie developments in categorization and naming such developments depend on other abilities as well Studyin the past experiences of the child and the particular context in which the behavior is exhibited may be a more meaningful approach to understanding changes in categorization and ultimately its relation to language.     

The development of visual categorization based on high-level cues

This study investigated the development of rapid visual object categorization. N = 20 adults (Experiment 1), N = 21 five to six-year-old children (Experiment 2), and N = 140 four-, seven-, and eleven-month-old infants (Experiment 3; all predominantly White, 81 females, data collected in 2013–2020) participated in a fast periodic visual stimulation electroencephalographic task. Similar categorization of animal and furniture stimuli emerged in children and adults, with responses much reduced by phase-scrambling (R² = .34–.73). Categorization was observed from 4 months, but only at 11 months, high-level cues enhanced performance (R² = .11). Thus, first signs of rapid categorization were evident from 4 months, but similar categorization patterns as in adults were recorded only from 11 months on.     

Contextual control of pavlovian feature-positive and feature-negative discriminations

Three pigeons were trained with a Pavlovian serial feature-positive (F-P) discrimination task in a light context, in which the houselight was on, and with a Pavlovian serial feature-negative (F-N) discrimination task in a dark context, in which the houselight was off. Three other pigeons were trained with the F-P task in the dark context and the F-N task in the light context. These two contextual conditions were changed randomly trial by trial. The former birds learned the tasks within 60 sessions, by responding exclusively to the target keylight after the feature tone in the light context and by responding exclusively to the target not preceded by the feature in the dark context. Two of the latter birds required separate training of the F-P and the F-N tasks to acquire the discrimination: responding exclusively to the target after the feature in the dark context and responding exclusively to the target not preceded by the feature in the light context. The third bird, however, failed to learn the discrimination even with separate training. These results indicate that the four-term contingency (the context-feature-target-food relationship) controlled the birds’ behavior in the Pavlovian setting. The insertion of a temporal gap between the feature and the target impaired the F-N discrimination, although it had little effect on the F-P discrimination.     

Learning While Testing

Abstract

This study investigated the performance of preschool and kindergarten children with visual discrimination exercises drawn from reading readiness materials prior to visual discrimination training. The exercises contained three sources of stimuli: representations of objects, letters, and words. Results indicate that many preschoolers and most kindergartners measured possess the skills necessary to successfully perform visual discrimination exercises. The 8s were able to discriminate representations of objects and letters equally well; however, word stimuli were significantly harder to discriminate than either representations of objects or letters. Results indicate that visual discrimination training should be provided to pre-readers on a selected basis.     

Detecting blickets: how young children use information about novel causal powers in categorization and induction

Three studies explored whether and when children could categorize objects on the basis of a novel underlying causal power. To test this we constructed a "blicket detector," a machine that lit up and played music when certain objects were placed on it. First, 2-, 3- and 4-year-old children saw that an object labeled as a "blicket" would set off the machine. In a categorization task, other objects were demonstrated on the machine. Some set it off and some did not. Children were asked to say which objects were "blickets." In an induction task, other objects were or were not labeled as "blickets." Children had to predict which objects would have the causal power to set off the machine. The causal power could conflict with perceptual properties of the object, such as color and shape. In an association task the object was associated with the machine's lighting up but did not cause it to light up. Even the youngest children sometimes used the causal power to determine the object's name rather than using its perceptual properties and sometimes used the object's name rather than its perceptual properties to predict the object's causal powers. Children rarely categorized the object on the basis of the associated event. Young children also sometimes made interesting memory errors-they incorrectly reported that objects with the same perceptual features had had the same causal power. These studies demonstrate that even very young children will easily and swiftly learn about a new causal power of an object and spontaneously use that information in classifying and naming the object.     

Flexible and context-dependent categorization by eighteen-month-olds

One hundred 18-month-olds were tested using sequential touching and following 4 different priming contexts using sets of toys that could be simultaneously categorized at either the basic or global level. An exact expression of the expected mean sequence length for arbitrary categories was derived as a function of the number of touches made, and a finite mixture model analytic method was also used to explore individual variability in categorization. Toddlers could categorize flexibly and spontaneously selected the level of categorization as a function of the prior prime. Perceptual Variability emerged as a predictor of the level at which infants subsequently categorized. The infants were also able to classify objects as members of both basic- and global-level categories simultaneously.     

Components of Reading Ability: Multivariate Evidence for a Convergent Skills Model of Reading Development

The objectives of this series of 3 studies were (a) to evaluate whether French-speaking children mainly use phonological mediation in the first stage of reading acquisition in a silent-reading task and (b) to examine the role of phonological processing in the construction of the orthographic lexicon. Forty-eight French children were followed from kindergarten to the end of Grade 2. Their phonological skills were assessed using a semantic categorization task with homophone and visual foils (Study 1); their orthographic skills were assessed using a choice task involving a correct exemplar, a homophone, and a visual foil (Study 2). In the semantic categorization task, the differences between the visual and homophone foils increased with time, as the homophone foils were more and more likely to be chosen. In the orthographic choice task, performance improved with time, but errors were more likely to involve homophone foils. The results obtained by two subgroups of children who differed in their level of orthographic expertise at the end of Grade 2 (Study 3) indicated that, 1 year earlier (at the end of Grade I), the future "expert" spellers were more likely than the future "poor" spellers to use phonological processing in silent reading (semantic categorization task). Moreover, in Grade 1, future expert spellers' phonological skills in reading aloud and in spelling from dictation (pseudoword tasks) were better than those of future poor spellers, and future expert spellers also had better phonological awareness skills at the beginning of the last year of kindergarten. These results suggest that French-speaking children use phonological mediation in silent-reading tasks and that phonological processing contributes to the construction of the orthographic lexicon.