Perisaccadic flash mislocalization depends on whether a background stimulus appears or disappears around the time of the flash

摘要

A perisaccadic target-flash occurring in the dark tends to be mislocalized (e.g., Honda, 1991; Matin, 1976). This phenomenon is often explained as arising from an extraretinal (exR) signal that changes around the time of the saccade. However, Pola (2004, 2007) proposed that such mislocalization is not simply the effect of an exR signal, but is the outcome of flash retinal (R) signal persistence interacting with the exR signal. Besides accounting for perisaccadic mislocalization in the dark, this R-exR model suggests that the features of mislocalization with a background stimulus are a consequence of the R signal interacting with the background as well as the exR signal (Pola, 2010 VSS). The present study is concerned with the model's prediction that there is a difference between perisaccadic mislocalization when a background stimulus appears just after a flash and when the background disappears at the time of the flash. The model shows that, in the first case, the background (relative to the dark) increases the amount of mislocalization in the saccade direction, whereas, in the second case, the background decreases the amount of mislocalization in the saccade direction. These predictions are compared with experimental results of a study with background visible just after a flash (Matin, Matin, Pola & Kowal, 1969), and the findings of a study with background disappearing at the time of a flash (Dassonville, Schlag & Schlag-Rey, 1995). In both situations, the model's response turns out to be essentially the same as the empirical findings. This correspondence between model and data, along with previous results (Pola, 2004, 2007, 2010) shows that the R-exR model is able to account for perisaccadic mislocalization in a wide range of visual circumstances, i.e., in the dark, with sequential stimuli, and with different spatial and temporal features of background events.