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Participants from ages 5 to 99 years completed 2 time estimation tasks: a temporal generalization task and a temporal bisection task. Developmental differences in overall levels of performance were found at both ends of the life span and were more marked on the generalization task than the bisection task. Older adults and children performed at lower levels than young adults, but there were also qualitative differences in the patterns of errors made by the older adults and the children. To capture these findings, the authors propose a new developmental model of temporal generalization and bisection. The model assumes developmental changes across the life span in the noisiness of initial perceptual encoding and across childhood in the extent to which long-term memory of time intervals is distorted.

The extent to which human discrimination learning is based on elemental or configural stimulus representations was examined in 7 experiments. In Experiments la and 1b, participants were able to learn nonlinear discrimination problems in a food-allergy task. In unique-cue theories, such learning is explained by individual stimulus elements acquiring independent connections with the outcome and also combining to form unique cues that function elementally. In Stage 1 of Experiments 2, 3, and 4a-c, Food A signaled an allergy outcome (O) (A -O) when presented alone but signaled no allergy (AB -no 0) when paired with Food B. In Stage 2, Food B was paired with the allergy (B -»O). In a test phase, the original discrimination between A and AB was found to be intact, at variance with the unique-cue theory. By contrast, in Experiments 5a, 5b, and 6, an effect of the B -* O trials on the A-AB discrimination was observed with training procedures previously found by D. A. Williams (1995) to encourage elemental processing. Experiment 7 showed that the influence of B -* O trials on the A-AB discrimination was unaffected by pretreatments designed to foster an elemental processing strategy. Overall, these results are problematic for unique-cue theories and instead imply that, by default, configurations of elements form the representational basis of simple discrimination learning in humans.

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