Identification of Highlights in Early Vision
R.A. Rensink and P. Cavanagh, Dept. of Psychology, Harvard University, Cambridge, MA.

Investigative Ophthalmology & Visual Science, 35:1623. 1994. [ARVO 1994; Sarasota, FL.]

Purpose. To determine whether highlights are rapidly identified at early levels of vision.

Methods. Visual search experiments were carried out using simple black and white figures corresponding to shiny objects lit from various directions. These included, for example, depictions of cylinders with highlights positioned at various heights (see figure). Targets and distractors differed only in the arrangement of their constituent regions, allowing them to be distinguished by the position of the highlights on the corresponding objects.

Results. Three observers were tested. Search is rapid when the target corresponds to a shiny black object with a bottom highlight among objects with top highlights (view figure from rightside up). However, search slows down when the target corresponds to an object with a top highlight among objects with bottom highlights (view figure from upside down). This asymmetry in search speeds is destroyed when the contrast of the figures is reversed.

Conclusions. These results indicate that regions in the image can be rapidly identified as highlights at early levels of vision. They also suggest--as for several other rapid recovery processes--that an assumption of lighting from above is used as a simplifying constraint.

(Figure viewed upside down)

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