Holistic crowding: Selective interference between configural representations of faces in crowded scenes

Abstract

It is difficult to recognize an object that falls in the peripheral visual field; it is even more difficult when there are other objects surrounding it. This effect, known as crowding, could be due to interactions between the low-level parts or features of the surrounding objects. Here, we investigated whether crowding can also occur selectively between higher level object representations. Many studies have demonstrated that upright faces, unlike most other objects, are coded holistically. Therefore, in addition to featural crowding within a face (M. Martelli, N. J. Majaj, & D. G. Pelli, 2005), we might expect an additional crowding effect between upright faces due to interference between the higher level holistic representations of these faces. In a series of experiments, we tested this by presenting an upright target face in a crowd of additional upright or inverted faces. We found that recognition was more strongly impaired when the target face was surrounded by upright compared to inverted flanker (distractor) faces; this pattern of results was absent when inverted faces and non-face objects were used as targets. This selective crowding of upright faces by other upright faces only occurred when the target-flanker separation was less than half the eccentricity of the target face, consistent with traditional crowding effects (H. Bouma, 1970; D. G. Pelli, M. Palomares, & N. J. Majaj, 2004). Likewise, the selective interference between upright faces did not occur at the fovea and was not a function of the target-flanker similarity, suggesting that crowding-specific processes were responsible. The results demonstrate that crowding can occur selectively between high-level representations of faces and may therefore occur at multiple stages in the visual system.

Attention-Dependent Early Cortical Suppression Contributes to Crowding

“…However, we should not preclude the possibility that crowding occurs at multiple levels in the visual system. For example, Louie et al (2007) demonstrated a holistic crowding between high-level face representations, suggesting that face-selective areas (e.g., fusiform face area) might play a role in this kind of crowding (Louie et al, 2007). In the future, it would be important to investigate whether our conclusion can be generalized to other conditions and stimuli.…”

“…Fu et al (2010) observed that, when two stimuli were presented in the left and right visual fields, respectively (assuming little interaction between them), the C1 amplitude evoked by the simultaneous presentation of the two stimuli was equal to the sum of the C1 amplitudes evoked by presenting the stimuli separately. Similar to previous neurophysiological (Moran and Desimone, 1985;Miller et al, 1993;Luck et al, 1997) and fMRI studies (Kastner et al, 1998), we defined a suppression index between the target and flankers as (C1 T ϩ C1 F ) Ϫ C1 TϩF for the nearby and far conditions. C1 T and C1 F were the C1 amplitudes evoked by the target (T) and flankers (Near_F or Far_F), respectively.…”

Object-level visual information gets through the bottleneck of crowding

“…2; all subjects, P Ͻ 0.001). This reduction in discrimination of the target faces with the addition of flankers is due to crowding and has been demonstrated to result from interactions at the level of holistic face information (Farzin et al 2009;Louie et al 2007). Crowding resulted in a drop to chance-level performance in one subject (NS) and slightly above-chance performance in the other three subjects.…”

“…1C without flanking faces). Although difficult, observers can still readily recognize faces at this eccentricity (Louie et al 2007;McKone 2004). The faces were presented on a gray background, and each subtended 1.8 ϫ 2.6°of visual angle.…”

Effects of face feature and contour crowding in facial expression adaptation

“…Surrounding a stimulus by similar stimuli (flankers) reduces discriminability of the stimulus, the crowding effect. Adapting to a crowded stimulus does not reduce the adaptation aftereffect for simple features, such as oriented bars at high contrast (He, Cavanagh, & Intriligator, 1996;Rajimehr, Montaser-Kouhsari, & Afraz, 2003 More recent studies suggest, however, that reducing the discriminability of the adapting face by crowding with flanking faces (Louie, Bressler, & Whitney, 2007) reduces the aftereffect for complex stimuli (e.g., faces) at low contrast. Blake et al (2006) resolved this controversy by showing that crowding does not reduce the aftereffect for simple features (e.g., orientation-dependent threshold-elevation aftereffect, TEAE) at high-contrast, but does so for simple features at low contrast, suggesting the existence of response saturation for adapting stimuli at high contrast levels.…”