Abstract
Classical (Pavlovian) conditioning procedures can sometimes cause visual appearance to become dependent on a single new cue (Haijiang et al., 2005). Fiandt (1936) conducted a series of experiments in which perceived surface lightness was allegedly made dependent on new signals: a small bit of shadow, a button, or a tone (conditioned stimuli) were able to cause changes in lightness perception after being paired with a large cast shadow (which caused apparent lightening in a shaded part of a test display). Fiandt's finding has seldom if ever been cited after Brunswik (1956). Can his stimuli be used to demonstrate cue recruitment? We asked observers to report paint color for gray disks in shadow, by matching them to grayscale painted chips. Following Fiandt, the shadow's penumbra was mostly invisible, so light disks appeared as though painted dark gray (reverse Gelb effect). On training trials a small bit of penumbra (a “Schattenzunge”) and a large red rectangle (cast by red cellophane) were visible; after the observer made her match, the shadow caster and cellophane were moved up and down together, which moved the shadow off the disk and caused it to appear lighter. On test trials the red rectangle was visible while the Schattenzunge was not. Preliminary results were that stimuli came to appear lighter on training trials, but not test trials. Thus the Schattenzunge, but not the rectangle, was necessary for the learned lightening effect. The more arbitrarily visual signal was not learned as a lightness cue in this experiment.
NIH grants EY-013988 and P30 EY-001583