Human performance in object recognition changes with practice, even in the absence of feedback to the subject. The nature of the change can reveal important properties of the process of recognition. We report an experiment designed to distinguish between non-specific task learning and object-specific practice effects. The results of the experiment support the notion that learning through modification of object representations can be separated from secondary effects of practice, if appropriate response measures (specifically, the coefficient of variation of response time over views of an object) are used. The present results, obtained with computer-generated amoeba-like objects, corroborate previous findings regarding the development of canonical views and related phenomena with practice.... Visual recognition, Learning.