Perception time measured with the slope-transition paradigm (STP): category, set size, and task manipulations.

A perception time measure was obtained with the 'slope-transition paradigm' (STP), which is described in detail. In two experiments with the paradigm, participants viewed two sequential data frames, each presented for a wide range of durations. They made a binary response based on combined information from the two frames. The results showed piecewise linear response-time versus frame-duration functions with a slope-0 branch at short durations, followed by a slope-1 branch. The duration where the two branches met (the slope transition) was interpreted as the end of the perception of frame 1. For longer durations, the participant had completed the perception of frame 1 and was forced to waste time waiting for data from frame 2. In experiment 1, an odd-digit enumeration task was used, and set size and distractor category (even digits versus consonants) were varied. In experiment 2, a same/different task with digits was used and the type of judgment (literal versus parity) was varied. Perception time increased with set size. Distractor category and judgment type affected post-perceptual processes. The perception time measure of the STP is considered in relation to the attentional blink, repetition blindness, and object files.