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PubMed2004

Age differences in estimating arrival-time.

The present study examined the accuracy in extrapolating an occluded trajectory in relation to observer age. Adults and children aged 7, 10, and 13 were tested in a prediction-motion task which consisted of judging, after the occlusion of the final part of its path, the moment of arrival of a moving stimulus towards a specified position. Results showed that children as young as 7 years old are able to use the same strategy as adults in the extrapolation of an occluded moving object. However, accuracy in responses improves most significantly for occlusion times equal to or more than 400 ms and this improvement occurs mainly between 7 and 10 years of age. This confirms that children are less efficient in performing the computations necessary to extrapolate in time an occluded trajectory.

Adolescent↗

PubMed2003

Time-to-contact estimation of accelerated stimuli is based on first-order information.

The goal of this study was to test whether 1st-order information, which does not account for acceleration, is used (a) to estimate the time to contact (TTC) of an accelerated stimulus after the occlusion of a final part of its trajectory and (b) to indirectly intercept an accelerated stimulus with a thrown projectile. Both tasks require the production of an action on the basis of predictive information acquired before the arrival of the stimulus at the target and allow the experimenter to make quantitative predictions about the participants' use (or nonuse) of 1st-order information. The results show that participants do not use information about acceleration and that they commit errors that rely quantitatively on 1st-order information even when acceleration is psychophysically detectable. In the indirect interceptive task, action is planned about 200 ms before the initiation of the movement, at which time the 1st-order TTC attains a critical value.

Adult↗