A prominent view is that in crowding, information about the target is not completely lost but is pooled or integrated with the information from the contextual elements (Parkes et al.,
2001; Pelli et al.,
2004). Accordingly, crowding has been described as ‘excessive feature integration’ (Pelli et al.,
2004) and ‘texture perception when we do not wish it to occur’ (Parkes et al.,
2001). In terms of the underlying causes, crowding is thus seen as distinct from other perceptual phenomena such as masking (Levi, Hariharan, & Klein,
2002; Pelli et al.,
2004) and surround suppression (Petrov, Popple, & McKee,
2007) where similar interferences occur. In masking and surround suppression, information from the target is thought to be irretrievably lost (Parkes et al.,
2001; Pelli et al.,
2004; Petrov et al.,
2007). Masking occurs when the target and the contextual stimulus (called the mask) stimulate neural mechanisms responding to the same spatial location in the visual field and a process such as divisive inhibition (Foley,
1994; Heeger,
1992) reduces the incremental responses to the target. In surround suppression, the target and the contextual stimulus stimulate neural mechanisms responding to adjacent locations in the visual field, and the responses to the target are suppressed by neural inhibition that operates ‘over space’ (Cavanaugh, Bair, & Movshon,
2002; Kapadia, Westheimer, & Gilbert,
2000).