Orientation-specific effects in picture matching and naming

In two experiments, subjects made timed decisions about the second of two s equentially presented rotated drawings of objects. When the two objects wer e physically identical, response times to decide whether the two drawings d epicted the same object varied as a function of the shortest distance betwe en the orientation of the second drawing and either the orientation of the previous drawing or the upright. This was found for both short (250-msec) a nd long (2-sec) interstimulus-intervals. The result was also obtained when subjects named the second drawing after deciding whether the first drawing faced left or right. Following repeated experience with the drawings in the left/right task over four blocks of trials, time to name the second drawin g in the same-object sequences was independent of orientation. These result s suggest that, initially, object- and orientation-specific representations san be formed following a single presentation of a rotated object and subs equently used to identify drawings of the same object at either the same or different orientations. Alignment of the second drawing with either the ca nonical representation or the new representation at the previous orientatio n is achieved by normalization through the shortest path. Following experie nce with the objects, orientation-invariant representations are formed.