Experimental setup for attentional modulation of surround suppression.
- Author
- Frederik Beuth
Data: Sundberg, Mitchell, Reynolds, 2009, Fig. 6F
Significant results (p. 957, left column):
- In attend away condition, surround suppression is weakest for the highest contrast and becomes stronger for lower ones.
- Attention to the center reduces surround suppression, whereby attention to the surround increases it. The effect is visible at all contrasts.
- The outlined results are prominent, but no significance test was executed.
Setup:
- Use primary spatial amplification as we assume that attention comes from tracking the object. Feature-based attention could also be assumed as a certain object is attended. However, it will not work because all objects are identical and could not be distinguished over their features. => We model it with 90% spatial and 10% feature-based attention as this results in the best fits to the data.
- Spatial attention has the same size as stimulus
- Contrast of center stimulus is variable
- Surround stimulus has always highest contrast
- Stimuli have a size of 2°, eccentricity is unknown. However, this size is very small compared to V4 rf sizes at all eccentricities, so we assume that a stimulus falls only in a single V4 receptive field.
Calibration of the fit:
- 1) Fit contrast response parameters (sigma, vE, pE)
- 2) Calibrate amount of surround suppression to fit attend away condition. Use pSUR>=2 to get a notable difference between attend-away and attend-surround
- 3) Attention to fit attend surround. Attend center is mostly correct as the response will probably saturate