Perceptual Fading of a Stabilized Cortical Image: Replication in the Undergraduate Classroom

Active learning exercise procedure. The adaptation condition began with 180 s of adaptation. Between each trial was a pause of 10 s, during which a high contrast grating was presented at the upper location in the adaptation condition; no such grating was shown between trials in the control condition. The contrast of the upper grating was randomly determined on each trial; 10 contrast matches were made for each contrast level within each condition. ISI, inter-stimulus interval.

Sliding scale. A visual representation of the change to the sliding scale (top numbers, contrast levels; bottom numbers, position values). At a random position value, the logarithmic scale was cut. The contrast of 0.1, which corresponded to the cut position value became the beginning of the sliding scale. All contrasts before this cut were added to the end of the scale.

Blakemore et al. (1971) replication results. Perceived contrast as a function of physical contrast. Each point represents the average of 20 matches (open triangles, control condition; red triangles, adaptation condition). Error bars, standard error of the mean.

Active learning exercise results. Perceived contrast as a function of physical contrast for two example observers. Each point represents the average of ten matches (black dots, control condition; red dots, adaptation condition).