General magnitude representation in human infants

Abstract

Behavioral demonstrations of reciprocal interactions among the dimensions of space, number, and time, along with evidence of shared neural mechanisms in posterior parietal cortex, are consistent with a common representational code for general magnitude information. Although much recent speculation has concerned the developmental origins of a system of general magnitude representation, direct evidence in preverbal infants is lacking. Here we show that 9-month-olds transfer associative learning across magnitude dimensions. For example, if shown that larger objects were black and had stripes and that smaller objects were white and had dots, infants expected the same color-pattern mapping to hold for numerosity (i.e., greater numerosity: black with stripes; smaller numerosity: white with dots) and duration (i.e., longer-lasting objects: black with stripes; shorter-lasting objects: white with dots). Cross-dimensional transfer occurred bidirectionally for all combinations of size, numerosity, and duration. These results provide support for the existence of an early-developing and prelinguistic general magnitude system, whereby representations of magnitude information are (at least partially) abstracted from the specific dimensions.

Figure 1

Results for each condition in Experiment 1. Mean looking time (seconds) is reported for habituation and test phases; error bars represent standard errors.

Figure 2

Space & Number condition in Experiment 2. Examples of stimuli for habituation and test phases for both groups (top panels). Mean looking time (seconds) is reported for habituation and test (bottom panel); error bars represent standard errors. Results are collapsed across group (size-to-numerosity and numerosity-to-size), as statistical analyses revealed no significant differences related to group (see Main text).

Figure 3

Space & Time condition in Experiment 2. Examples of stimuli for habituation and test phases for both groups (top panels). Mean looking time (seconds) is reported for habituation and test (bottom panel); error bars represent standard errors. Results are collapsed across group (size-to-duration and duration-to-size), as statistical analyses revealed no significant differences related to group (see Main text).

Figure 4

Number & Time condition in Experiment 2. Examples of stimuli for habituation and test phases for both groups (top panels). Mean looking time (seconds), collapsed across group, is reported for habituation and test (bottom panel); error bars represent standard errors. Results are collapsed across group (numerosity-to-duration and duration-to-numerosity), as statistical analyses revealed no significant differences related to group (see Main text).