Implicit processing of shadows.

Using synthetic objects, I investigate whether recognition performance is sensitive to different features of cast and attached shadows. Participants were required to recognise familiar objects presented to central vision while the presence, position and shape of cast and attached shadows were systematically manipulated. Costs in response time were found for naming objects in incongruent lighting and shadow conditions, that is, when the object was presented with a cast shadow that originated from a different object and when it was also non-congruently illuminated (e.g. attached shadow indicating that the source of light was from the left, and cast shadow indicating that the source of light was from the right).