When peripheral vision is refractory to predictions, extrapolation and memory effects

There are important differences between central and peripheral vision. With respect to shape, contours retain phenomenal sharpness, although clutter makes identification hard, and some contours disappear if they are near other contours. Because of this, physically uniform textures may appear non-uniform: Honeycomb illusion (Bertamini et al., 2016). For extended textures or repeated patterns, it is reasonable to expect that continuity helps preserve the phenomenal appearance outside central vison. Other mechanisms may also be important, for extended surfaces uniformity may have ecological foundation, and provide a strong prior. Some aspects enter awareness only if attention is directed to the region of the periphery. Otherwise, summary statistics are extracted and patterns with identical statistics are experienced as the same. Finally, peripheral appearance may also largely depend on memory. I will focus on examples in which physical continuity of a texture does not contribute to phenomenal continuity. A perceptual boundary becomes visible (although illusory), creating a phenomenal separation between central and peripheral vision. Because the texture is physically uniform its statistics are the same as in central vision. Moreover, multiple fixations do not accumulate effective information. To explain these cases I will argue that some of the specific properties of peripheral vision are independent of central vision and covert attention. But this does not mean that these mechanisms are not adaptive, the explanation for how objects appear in the periphery is a need to achieve constancy. Adaptive mechanisms are not necessarily perfect, and that is why illusions are interesting and illuminating.