Time-to-Contact: More Than Tau Alone.


Hancock, P.A., & Manser, M.P. (1997). Time-to-contact: More than tau alone. Ecological Psychology, 9(4), 265-297.

Two time-to-contact (Tc) experiments are reported that manipulated the manner in which a visually simulated target vehicle disappeared from the screen. In both experiments, on condition featured the traditional, spontaneous disappearance of the vehicle. A contrasting condition featured the occlusion of the vehicle behind a natural object. The available visual information was essentially equivalent in each condition.  If Tc is specified by information in the expanding optic array alone, the two conditions should produce equivalent estimates of Tc results of each experiment, however, showed estimates with 14% and 12% greater accuracy in the occlusion condition compared to the disappearance condition. This implies that Tc judgements depend on more than the rate of optical expansion. In addition to the occlusion manipulation factors influencing the accuracy of Tc estimates with time-judgement ability, participants also performed a time-production task with the same temporal structure as the Tc task but with no graphic scene representation. A positive relation was found but further clarification is still needed between these two capabilities.

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