Dichotomous perception of animal categories in infancy

ABSTRACT

Although there is a wealth of knowledge on categorization early in life, there are still many unanswered questions about the nature of category representation in infancy. For example, it is unclear whether infants are sensitive to boundaries between complex categories, such as types of animals, or whether young infants exhibit such sensitivity without explicit experience in the lab. Using a morphing technique, we linearly altered the category composition of images and measured 6.5-month-olds’ attention to pairs of animal faces that either did or did not cross the categorical boundary, with the stimuli in each pair being equally dissimilar from one another across the two types of image pairs. Results indicated that infants dichotomize the continua between cats and dogs and between cows and otters, but only when the images are presented in their canonical, upright orientations. These findings demonstrate a propensity to dichotomize early in life that could have implications for social categorizations, such as race and gender.

KEYWORDS:

• Dichotomization in infancy
• categorical perception
• animal knowledge in infancy
• early conceptual development

Acknowledgement

The authors would like to thank the infants and parents who participated in this study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. When the data are restricted to only include pairs of trials in which infants fixated on every face, infants’ performance remains significantly above chance, M = 52.48%, SE = 0.85%, t(10) = 2.93, p = .02, d = 0.89.

2. When the data are restricted to only include pairs of trials in which infants fixated on every face, infants’ score is no longer significantly different from chance, M = 51.43%, SE = 1.54%, t(15) = 0.93, p = .37, d = 0.23.

3. When the data are restricted to only include pairs of trials in which infants fixated on every face, infants’ score is marginally above chance, M = 53.79%, SE = 1.82%, t(15) = 2.07, p = .06, d = 0.52.

4. When the data are restricted to only include pairs of trials in which infants fixated on every face, infants’ mean score is still not significantly different from chance, M = 51.47%, SE = 1.44%, t(29) = 1.02, p = .32, d = 0.19.

Additional information

Funding

This research was supported by grants from the National Science Foundation [grant number BCS-1121096] and the National Institute of Child Health and Human Development [grant number HD075829]; Eunice Kennedy Shriver National Institute of Child Health and Human Development.