The Blindfold Test: Helping to decide whether an effect reflects visual processing or higher-level judgment

Abstract

Experimenters often ask subjects to rate displays in terms of high-level visual properties, such as animacy. When do such studies measure subjects’ visual impressions, and when do they merely reflect their judgments that certain features should indicate animacy? Here we introduce the ‘Blindfold Test’ for helping to evaluate the evidence for whether an effect reflects perception or judgment. If the same effect can be obtained not only with visual displays but also by simply describing those displays, then subjects’ responses may reflect higher-level reasoning rather than visual processing—and so other evidence is needed in order to support a ‘perceptual’ interpretation. We applied the Blindfold Test to three past studies in which observers made subjective reports about what they were seeing. In the first two examples, subjects rated stimuli in terms of high-level properties: animacy and physical forces. In both cases, the key findings replicated even when the visual stimuli were replaced with (mere) descriptions, and we conclude that these studies cannot by themselves license conclusions about perception. In contrast, a third example (involving motion-induced blindness) passed the test: subjects produced very different responses when given descriptions of the displays, compared to the visual stimuli themselves—providing compelling evidence that the original responses did not merely reflect such higher-level reasoning. The Blindfold Test may thus help to constrain interpretations of the mental processes underlying certain experimental results—especially for studies of properties that can be apprehended by both seeing and thinking.