Sensitivity variations in the visual system, contrast resolution and eye movements.

Attention is drawn to the fact that under normal visual conditions the sensitivity of the receptor units of the visual system are subject to spatial and temporal variations, and that consequently in performing pattern recognition the visual cortex has to discriminate between external luminance structure and internal sensitivity structure. It is suggested that eye movements are the method by which this discrimination is performed. In a simplified model analysis it is shown that eye movements are a suitable mechanism for this discrimination. Implications of this model for detection threshold and stabilized retinal images are discussed. A new interpretation of the adaptation to sine wave grids is given.