Saccadic suppression of image displacement

These results indicate that the human perceptual system neglects many useful pieces of information when it comes to spatially localizing target displacements occurring during a saccade.

Surprisingly, in contrast to the perceptual system, the motor system is able to access precise spatial information in order to render precise motor actions during a saccade (Bridgeman, Lewis, Heit, & Nagle, 1979; Prablanc & Martin, 1992).

According to this model, three sources of information must be present in order to maintain visual constancy and successfully determine the direction of a target displacement: the target position prior to the saccade, extra retinal information, and a retinal error signal from the corrective saccade to determine the actual direction of target movement by comparing it to the efference copy and proprioceptive inflow (Deubel et al., 1996).

Using the device pictured on the right, Ziat et al. (2010) demonstrated a phenomenon akin to the saccadic suppression of image displacement (Bridgeman et al., 1975) in the tactile system.

Under certain conditions participants failed to detect that dots had changed location as they moved their fingers over the tactile display.

Apparatus. Refreshable Braille cells are embedded in an inclined surface (left). A sliding potentiometer supports two semicylindrical cradles forming a guide that can be relocated on a Velcro surface to accommodate the participants' anatomical differences.