Effect of Motion on the Recognition of Area by Rhesus Monkeys in a Pseudo-Matching Task

We examined the effect of target motion on the visual recognition of target area in rhesus monkeys. We used a pseudo-matching visual task, where ten adult monkeys were trained to recognise and point out the bigger one of two achromatic squares of different areas but having the same luminance and presented on the same background. The video screen was placed 0.5 m in front of their faces. The two areas were randomly sampled out of five areas (49, 72.25, 100, 132.25, and 169 mm²). The speed of the targets was varied in this paradigm (0, 6, 11, 16, 21, or 26 deg s⁻¹). Performance in terms of area recognition thresholds was calculated for each monkey on the basis of 100 trials in standardised environmental conditions. Statistical analysis showed that performance with a target speed of 16 deg s⁻¹ was significantly better than in the other conditions (p<0.01). We conclude that this pseudo-matching task, based on a cognitive paradigm, reveals a significant effect of motion on the visual recognition of area in rhesus monkeys. The activities of specific cortical areas (V4 and V5) should be studied by other techniques in order to characterise those involved in remembering an object's qualities and those responding to motion. The links between V4, V5, and inferior temporal cortex could be tested with the aid of this pseudo-matching task.