Perceived direction of a moving stimulus is affected by the direction of the preceding stimulus. In the Visual Motion Priming (VMP) phenomenon (Pinkus & Pantle, 1997, Vision Res, 37:541-52), a directionally ambiguous motion step (test stimulus) appears to be in the same direction as the preceding unambiguous motion step (prime stimulus). The purpose of the present study is to elucidate spatial frequency characteristics of this phenomenon. Using spatially superimposed sinusoidal gratings, magnitude of the priming effect was measured by varying the spatial frequencies of the test and the priming stimuli. The results show that the effect of VMP was dominant when the spatial frequency of the priming stimulus was lower than the test stimulus. These findings are discussed in terms of local motion detection systems.

The present study examined the effects of arm properties involving arm width and obstructive objects on radial maze performance in goldfish (Carassius auratus). Three groups of goldfish were trained to perform a typical win-shift free choice task in one of the three conditions of an eight-arm radial water maze. Arm width of the maze was 5 cm for Group 5 cm (=3) and 3 cm for Group 3 cm (=3). For Group curtain (=4), arm width was 5 cm but a curtain made of 0.5 mm thick silicon was set in each arm. To enhance arm identity, some arms of the mazes were differentially colored and different objects were placed on the floor of the arms. Group 3 cm made significantly greater correct responses than Group 5 cm and Group curtain within the initial eight choices of a trial. Performance of Group 5 cm and Group curtain was almost chance level during the five training blocks of eight trials. Group 5 cm showed significantly greater re-entry errors to complete trials than Group 3 cm. Arm width proved to affect the goldfish’s performance, but the introduction of curtain did not. Several causes for the results were discussed.