General magnitude representation in human infants

Demonstrations of reciprocal behavioral 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 with stripes and smaller objects were white with dots, infants expected the same color/pattern mapping to hold for numerosity (i.e., greater numerosity: black/stripes; smaller numerosity: white/dots) and duration (i.e., longer-lasting objects: black/stripes; shorter-lasting objects: white/dots). Cross-dimensional transfer occurred bi-directionally for all combinations of size, numerosity, and duration. These results provide support for an early-developing and pre-linguistic general magnitude system, whereby representations of magnitude information are (at least partially) abstracted from the specific imensions