Distinct cognitive mechanisms involved in the processing of single objects and object ensembles

Abstract

Behavioral research has demonstrated that the shape and texture of single objects can be processed independently. Similarly, neuroimaging results have shown that an object's shape and texture are processed in distinct brain regions with shape in the lateral occipital area and texture in parahippocampal cortex. Meanwhile, objects are not always seen in isolation and are often grouped together as an ensemble. We recently showed that the processing of ensembles also involves parahippocampal cortex and that the shape and texture of ensemble elements are processed together within this region. These neural data suggest that the independence seen between shape and texture in single-object perception would not be observed in object-ensemble perception. Here we tested this prediction by examining whether observers could attend to the shape of ensemble elements while ignoring changes in an unattended texture feature and vice versa. Across six behavioral experiments, we replicated previous findings of independence between shape and texture in single-object perception. In contrast, we observed that changes in an unattended ensemble feature negatively impacted the processing of an attended ensemble feature only when ensemble features were attended globally. When they were attended locally, thereby making ensemble processing similar to single-object processing, interference was abolished. Overall, these findings confirm previous neuroimaging results and suggest that distinct cognitive mechanisms may be involved in single-object and object-ensemble perception. Additionally, they show that the scope of visual attention plays a critical role in determining which type of object processing (ensemble or single object) is engaged by the visual system.

The Contribution of Object Shape and Surface Properties to Object Ensemble Representation in Anterior-medial Ventral Visual Cortex

“…Interestingly, this ability comes at the expense of losing the ability to provide fine details about the individual objects in the ensemble (e.g., Alvarez & Oliva, 2008;Chong & Treisman, 2003;Ariely, 2001;Parkes, Lund, Angelucci, Solomon, & Morgan, 2001;Watamaniuk & Duchon, 1992;Williams & Sekuler, 1984). This demonstrates that there is a tradeoff across these different visual perceptual processes, and consistent with this notion, we have recently demonstrated that there may be different underlying cognitive mechanisms supporting single-object versus object ensemble perception (Cant, Sun, & Xu, 2015).…”

Differential hemispheric and visual stream contributions to ensemble coding of crowd emotion

“…Much behavioral evidence has been accumulated supporting this notion 6,7,11–15,21,99–103, but see 104 , although only a few recent fMRI studies have compared the neural representations of ensemble coding and individual processing 105–107 . Cant and Xu 105,106 showed that PPA and LO were preferentially engaged in texture perception and object processing, respectively; and Huis in’t Veld and de Gelder 107 showed the greater anticipatory and action preparation activity in the areas including IPL, SPL, SFG, and premotor cortex for interactive body movement of a group of panicked people, compared to an unrelated movement of individuals.…”

Ensemble coding of crowd emotion: Differential hemispheric and visual stream contributions

“…Different patterns of hemispheric lateralization for the crowd emotion vs. individual emotion processing suggest that they may rely on qualitatively distinct systems. Much behavioral evidence has been accumulated supporting this notion (e.g., Alvarez & Oliva, 2008;Ariely, 2001;Cant, Sun, & Xu, 2015;Chong et al, 2008;Chong & Evans, 2011;Chong & Treisman, 2005;Choo & Franconeri, 2010;Corbett & Oriet, 2011;Haberman, Brady, & Alvarez, 2015;Haberman & Whitney, 2010;Im & Halberda, 2013;Leib et al, 2012;Parkes et al, 2001, but see Myczek & Simons, 2008, although only a few recent fMRI studies have compared the neural representations of ensemble coding and individual processing (e.g., , 2017Huis in't Veld & de Gelder, 2015). Xu (2015, 2017) showed that PPA and LO were preferentially engaged in texture perception and object processing, respectively; and Huis in't Veld and de Gelder (2015) showed the greater anticipatory and action preparation activity in the areas including IPL, SPL, SFG, and premotor cortex for interactive body movement of a group of panicked people, compared to an unrelated movement of individuals.…”