“School of Cognitive Sciences”

Back to Papers Home
Back to Papers of School of Cognitive Sciences

Paper   IPM / Cognitive Sciences / 8974
School of Cognitive Sciences
  Title:   Topographic map of the motion aftereffect
  Author(s): 
1.  A Ezzati
2.  Ashkan Golzar
3.  S.R. Afraz
  Status:   In Proceedings
  Proceeding: The European Conference on Visual Perception (ECVP)
  Year:  2006
  Supported by:  IPM
  Abstract:
Topographic organization of the motion aftereffect was measured on small test stimuli after adaptation to motion. The stimuli were random dots embedded in a 969 grid. In each adaptation trial, the dots in the central 565 grid holes were coherently moving in one direction for 5 s. After adaptation, a small random dot pattern filling one of the randomly selected grid holes was presented moving at various speeds for 0.2 ms. the subjects' task was to report perceived direction of the test stimulus by pressing one of two keys on the keyboard. The subjects' accuracy in direction discrimination was plotted as a function of test stimulus speed. Psychometric function shift in adapted trials compared to the non-adapted control condition was measured with fitted logistic curves. The shift value was defined as the strength of the motion aftereffect (MAE). To provide a fine topographic map of MAE we measured its strength for all grid holes. We found that this strength is highest in the internal edge of the adaptation area, parallel to the motion direction (p < 0.03). We also found a small positive aftereffect in background areas adjacent to the adaptation area. This background effect was asymmetrically stronger in areas in the direction of motion.

Download TeX format
back to top
scroll left or right