Figure 2

Schematic showing the test phases of Experiment 2a and 2b. In Experiment 2a, both the adaptation and test stimuli were horizontal and vertical Gabor patches, while the reference was a white noise burst shown in black. In Experiment 2b, both the adaptation and test stimuli were high-pitch and low-pitch sounds (2000 Hz and 500 Hz pure tones shown in black), while the reference was a Gaussian blob. Each test trial began with a top-up period in which two repeats of each stimulus configuration, as depicted in the preceding adaptation phase, were repeated. Following the top-up period, the reference lasting 320 ms and test stimulus, whose duration varied in seven logarithmically spaced steps from 237 to 421 ms, were presented successively. Once the test stimulus had disappeared, subjects made an unspeeded, two-alternative forced-choice duration discrimination judgment via the computer keyboard.