Jean-Pierre Thibaut

The development of features in object concepts

According to one productive and influential approach to cognition, categorization, object recognition, and higher level cognitive processes operate on a set of fixed features, which are the output of lower level perceptual processes. In many situations, however, it is the higher level cognitive process being executed that influences the lower level features that are created. Rather than viewing the repertoire of features as being fixed by low-level processes, we present a theory in which people create features to subserve the representation and categorization of objects. Two types of category learning should be distinguished. Fixed space category learning occurs when new categorizations are representable with the available feature set. Flexible space category learning occurs when new categorizations cannot be represented with the features available. Whether fixed or flexible, learning depends on the featural contrasts and similarities between the new category to be represented and the individuals existing concepts. Fixed feature approaches face one of two problems with tasks that call for new features: If the fixed features are fairly high level and directly useful for categorization, then they will not be flexible enough to represent all objects that might be relevant for a new task. If the fixed features are small, subsymbolic fragments (such as pixels), then regularities at the level of the functional features required to accomplish categorizations will not be captured by these primitives. We present evidence of flexible perceptual changes arising from category learning and theoretical arguments for the importance of this flexibility. We describe conditions that promote feature creation and argue against interpreting them in terms of fixed features. Finally, we discuss the implications of functional features for object categorization, conceptual development, chunking, constructive induction, and formal models of dimensionality reduction.

Developing Motor Planning over Ages.

Few studies have explored the development of response selection processes in children in the case of object manipulation. In the current research, we studied the end-state comfort effect, the tendency to ensure a comfortable position at the end rather than at the beginning of simple object manipulation tasks. We used two versions of the unimanual bar transport task. In Experiment 1, only 10-year-olds reached the same level of sensitivity to end-state comfort as adults, and 8-year-olds were less efficient than 6-year-olds. In each age group, childrens sensitivity did not increase during a session: i.e., either clearly showed the sensitivity or showed no sensitivity at all. Experiment 2 replicated these results when the bar was replaced by a pencil and when the task did not require much precision. However, when the task required more precision, 8-year-olds increased their level of sensitivity to the end-state comfort effect, whereas this was not the case for younger children. These results describe the development of advanced planning processes from 4 to 10 years of age as well as the positive effect of task constraints on the end-state comfort effect for 8-year-olds.

Cognitive load and semantic analogies: Searching semantic space.

The aim of the present study is to investigate the performance of children of different ages on an analogymaking task involving semantic analogies in which there are competing semantic matches. We suggest that this can best be studied in terms of developmental changes in executive functioning. We hypothesize that the selection of common relational structure requires the inhibition of other salient features, in particular semantically related matches. Our results show that childrens performance in classic A ∶ B ∶∶ C ∶ D analogy-making tasks seems to depend crucially on the nature of the distractors and the association strength between both the A and B terms and the C and D terms. These results agree with an analogy-making account (Richland, Morrison, & Holyoak, 2006) based on different limitations in executive functioning at different ages.

Dissociations between categorization and similarity judgments as a result of learning feature distributions

A dissociation between categorization and similarity was found by Rips (1989). In one experiment, Rips found that a stimulus halfway between a pizza and a quarter was categorized as a pizza but was rated as more similar to a quarter. Smith and Sloman (1994) discussed these results in terms of the role of necessary and characteristic features. In two experiments, participants had to learn to categorize novel artificial shapes composed of a nonsalient necessary feature combined with a salient characteristic feature. Participants categorized stimuli on the basis of a necessary feature, whereas their similarity judgments relied on characteristic features. The role of deep (essential) features in dissociations is considered. Results are discussed in terms of the differences between requirements of categorization and similarity judgments.

On the link between action planning and motor imagery: a developmental study

Abstract We examined the link between action planning and motor imagery in 6- and 8-year-old children. Action planning efficiency was assessed with a bar transport task. Motor imagery and visual imagery abilities were measured using a hand mental rotation task and a number (i.e., non-body stimuli) mental rotation task, respectively. Overall, results showed that performance varied with age in all tasks, performance being progressively refined with development. Importantly, action planning performance was correlated with motor imagery, whereas no relationship was evident between action planning and visual imagery at any age. The results showed that the ability to engage sensorimotor mechanisms when solving a motor imagery task was concomitant with action planning efficiency. The present work is the first demonstration that evaluating the consequences of the upcoming action in grasping depends on children’s abilities to mentally simulate the response options to choose the most efficient grasp.

The benefits and costs of comparisons in a novel object categorization task: Interactions with development

We investigated how children use within- or between-category comparisons to generalize novel names for novel objects on the basis of a nonsalient dimension (texture) rather than a salient one (shape). Previous studies have not experimentally addressed the costs associated with comparisons. We conjectured that increasing the number of stimuli to be compared (and thus, converging evidence in favor of the target texture-based generalization), might not necessarily be beneficial, especially in young children (3- to 4-year-olds vs. 5- to 6-year-olds). Our results showed that more evidence in favor of texture (i.e., more within-category exemplars sharing the same texture) did not linearly increase texture-based choices in the same way for younger and older children. They also revealed that between-category comparisons gave rise to texture-based generalizations in both age groups. Overall, our results show that even though within- and between-category comparisons contribute to generalizations based on texture, they also generate cognitive constraints that interact with age.

Local and Global Processing by Persons with Williams Syndrome: The Case of Visuo-Constructive Tasks

Williams syndrome (WS) is a rare genetically based neurodevelopmental disorder resulting in mild to moderate mental retardation. People with WS are known for their particular weakness in visuo-spatial construction. In a block-design task and a jigsaw-puzzle task, we compared WS persons with normally developing children matched for mental age. Three hypotheses were contrasted: (a) the standard local hypothesis, maintaining that WS persons are biased toward local processing and have a deficit in processing the global level of stimuli (Bellugi & al., 1994); (b) the disengaging from the global level hypothesis, which states that they have difficulties disengaging from global configurations when local processing is required (Pani & al., 1999); and a new hypothesis (c) the disengaging from the local level hypothesis, which states that they have difficulties in disengaging from salient local features when global processing is required. The third hypothesis is compatible with most of the observations regarding visuo-constructive problems in WS. We propose an interpretation of WS persons’ problems in terms of executive functions.

Actionality and mental imagery in children's comprehension of declaratives

Previous work has demonstrated that children understand sentences with actional verbs better than nonactional verbs. This actionality effect has been reported to be restricted to passives and to be independent of experimental context. The present experiment was conducted with 48 French-speaking children aged 5; 0-7; 11. The actionality effect was studied by systematically varying the voice of the test sentences and the voice of the interpretive requests. Pictures corresponding or not to the predicate-argument structure of the sentences were presented to the subjects, who were independently classified as visualizers or nonvisualizers, in order to investigate the relation between sentence actionality and mental imagery. The interaction between actionality, voice of sentence, and interpretive request revealed that the actionality effect depends on the type of task used in order to assess comprehension, and that it can be reversed in some conditions. Our results also suggest that the actionality effect is linked to mental imagery. Visualizers demonstrated better comprehension of actional sentences than nonvisualizers, whereas the reverse was true for non-actional sentences. Mental image may serve as a support for the computations involved in sentence comprehension.

An evaluation of scanpath-comparison and machine-learning classification algorithms used to study the dynamics of analogy making

In recent years, eyetracking has begun to be used to study the dynamics of analogy making. Numerous scanpath-comparison algorithms and machine-learning techniques are available that can be applied to the raw eyetracking data. We show how scanpath-comparison algorithms, combined with multidimensional scaling and a classification algorithm, can be used to resolve an outstanding question in analogy making—namely, whether or not children’s and adults’ strategies in solving analogy problems are different. (They are.) We show which of these scanpath-comparison algorithms is best suited to the kinds of analogy problems that have formed the basis of much analogy-making research over the years. Furthermore, we use machine-learning classification algorithms to examine the item-to-item saccade vectors making up these scanpaths. We show which of these algorithms best predicts, from very early on in a trial, on the basis of the frequency of various item-to-item saccades, whether a child or an adult is doing the problem. This type of analysis can also be used to predict, on the basis of the item-to-item saccade dynamics in the first third of a trial, whether or not a problem will be solved correctly.

Body and Soul: Do Children Distinguish between Foods When Generalizing Biological and Psychological Properties?.

ABSTRACT Research Findings: In 2 experiments, we tested whether children generalize psychological and biological properties to novel foods. We used an induction task in which a property (either biological or psychological) was associated with a target food. Children were then asked whether a taxonomically related and a script-related food would also have the property. In a yes/no task (Experiment 1) 9-year-olds preferentially generalized the property to taxonomically related foods, but 4- and 6-year-olds did not. In a forced-choice task (Experiment 2; 4- to 6-year-olds), children preferred the taxonomic choice over the script choice. This preference was weak at age 4 but established by age 5. In both experiments, and all age groups, biological properties, and psychological properties were treated similarly. It is argued that the children do not distinguish biological and psychological properties of food most likely because they believe that psychological properties are caused by biological dispositions. Practice or Policy: We argue that nutrition education should take advantage of children’s existing knowledge of food categories and how children generalize knowledge from 1 food to another. In particular, children have good knowledge of taxonomic categories and can best access that knowledge when they are required to compare different foods.