Categorization in infancy

doi:10.1016/S1364-6613(00)01752-6

Trends in Cognitive Sciences

Volume 5, Issue 10, 1 October 2001, Pages 443-450

https://doi.org/10.1016/S1364-6613(00)01752-6 Get rights and content

Abstract

Human infants display complex categoriztion abilities. Results from studies of visual preference, object examination, conditioned leg-kicking, sequential touching, and generalized imitation reveal different patterns of category formation, with different levels of exclusivity in the category representations formed by infants at different ages. We suggest that differences in levels of exclusivity reflect the degree to which the various tasks specify the relevant category distinction to be drawn by the infant. Performance in any given task might reflect prior learning or within-task learning, or both. The extent to which either form of learning is deployed could be determined by task context.

Section snippets

Results from visual preference studies

Early studies provided evidence that infants under one year of age could form perceptual category representations for visual patterns, such as schematic faces and geometric forms 3, 6. For example, when presented with dot pattern exemplars generated from either diamond, square, or triangle prototypes, 3–4-month-old infants generalized looking times to novel instances from the familiar form category, and displayed visual preferences for novel instances from novel form categories. Under certain

Results from object examining studies

Some investigators have used small, three-dimensional toy models of objects for stimuli and a manual habituation methodology to measure infant categoriztion performance. Oakes and colleagues have argued that combining looking with touching (i.e. examining) provides a measure of more active information processing about objects than just looking time 19, 20.

Outcomes from studies using visual preference and object examining methodologies are similar. For example, both 10- and 13-month-olds

Results from conditioned leg-kick studies

In the studies reviewed thus far, infants were given relatively brief exposure (typically 15–30 seconds per exemplar) to a number of exemplars (from 4–16) defining a category. They were then tested within a few minutes of familiarization. Studies in this section expose infants to a smaller number of exemplars (typically two or three) for a longer period of time (nine minutes). Exemplars are encountered at 24-hour intervals and testing occurs from 1–14 days later.

Initial findings suggested that

Results from generalized imitation studies

In these studies, various properties or actions appropriate to animals or vehicles are modelled to 14-month-olds 30, 31. The results are consistent with the idea that infants can represent broad, global-level category distinctions and not basic-level category distinctions. The infants generalized the properties of ‘drinking’ and ‘sleeping’ throughout the animal domain and the properties of ‘being keyed’ (i.e. inserting a key) and ‘giving a ride’ throughout the vehicle domain. For example, they

Results from sequential-touching studies

Results from sequential-touching studies are somewhat ambiguous. When presented with a set of toy replicas of animals or vehicles, infants again display evidence of global representations 32, 33. From 18–30 months, infants respond categorically only to global-level contrasts, such as vehicles versus animals, but do not respond categorically to basic-level contrasts within global categories. Not until 30 months do infants consistently represent basic-level contrasts within a global-level (e.g.

A possible synthesis: category learning versus category retrieval

Studies not requiring a familiarization phase (i.e. sequential touching and generalized imitation studies) find that infants separate entities according to broad, global category distinctions. By contrast, studies that require a familiarization phase (i.e. visual preference, object examination, and conditioned leg-kicking) find that infants can sort entities into global categories, but they can also form more finely tuned basic-level categories, and in some instances are even sensitive to the

Questions for future research

•
How does knowledge from outside the testing room affect infants’ within-task category learning?
•
What developing neural systems enable different kinds of category learning during infancy?
•
How does the acquisition of language affect the spontaneous categoriztions made by infants?
•
Are infant categories represented as sets of exemplars or in terms of summary structures?
•
Are there multiple category learning processes operating during infancy? If so, what are they and how do they operate?

Acknowledgements

The writing of this article was supported in part by European Commission RTN grant CT-2000-00065 and Economic and Social Research Council UK Grant R000239112 awarded to D.M., and also by Grant BCS-0096300 from the National Science Foundation awarded to P.C.Q.

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Trends in Cognitive Sciences

ReviewCategorization in infancy

Abstract

Section snippets

Results from visual preference studies

Results from object examining studies

Results from conditioned leg-kick studies

Results from generalized imitation studies

Results from sequential-touching studies

A possible synthesis: category learning versus category retrieval

Questions for future research

Acknowledgements

J. Exp. Psychol. Learn. Mem. Cognit.

J. Exp. Child Psychol.

Child Dev.

Dev. Psychol.

Dev. Psychol.

Infant Behav. Dev.

Infant Behav. Dev.

Dev. Psychol.

Annu. Rev. Psychol.

Behav. Brain Sci.

Dev. Psychol.

Rev. Gen. Psychol.

Visual perception and memory at birth

The nature and structure of infant form categories

J. Exp. Child Psychol.

The categorical representation of visual pattern information by young infants

Cognition

Development of categorization skills: changes in the nature and structure of infant form categories?

Dev. Psychol.

Evidence for representations of perceptually similar natural categories by 3-month-old and 4-month-old infants

Perception

Studies on the formation of perceptually based basic-level categories in young infants

Child Dev.

Parsing items into separate categories: developmental change in infant categorization

Child Dev.

A connectionist account of asymmetric category learning in early infancy

Dev. Psychol.

Infants’ detection of correlations among feature categories

Child Dev.

Developmental change in infants’ perception of correlations among attributes

Child Dev.

Review
Categorization in infancy