A Real-World Size Organization of Object Responses in Occipitotemporal Cortex

Abstract

SUMMARY While there are selective regions of occipito-temporal cortex that respond to faces, letters, and bodies, the large-scale neural organization of most object categories remains unknown. Here we find that object representations can be differentiated along the ventral temporal cortex by their real-world size. In a functional neuroimaging experiment, observers were shown pictures of big and small real-world objects (e.g. table, bathtub; paperclip, cup), presented at the same retinal size. We observed a consistent medial-to-lateral organization of big and small object preferences in the ventral temporal cortex, mirrored along the lateral surface. Regions in the lateral-occipital, infero-temporal, and parahippocampal cortices showed strong peaks of differential real-world size selectivity, and maintained these preferences over changes in retinal size and in mental imagery. These data demonstrate that the real-world size of objects can provide insight into the spatial topography of object representation.

Word meaning in the ventral visual path: a perceptual to conceptual gradient of semantic coding

“…In our study we could retrieve size and category information from the activity of occipito-temporal areas, but only at the 25 multivariate level, indicating that the activation of this information during passive word reading is more subtle and distributed compared to that directly evoked by looking at the pictures of the stimuli. Moreover, the discrepancy between findings implicating down-stream regions in the processing of size-related information (Konkle and Oliva, 2012) with our observation of an effect already in early, up-stream, regions could tentatively be explained in terms of differences in task requirements between the two studies (Martin, 2015). Generally speaking, the different perceptual and conceptual dimensions characterizing objects (Huth et al, 2012) and words (Just et al, 2010) semantics appear to be coded in a highly distributed fashion, encompassing visual and nonvisual cortices (Fernandino et al, 2015b).…”

“…However, in future studies we shall try to parametrize and thus model other visual as well as non-visual sensory properties implied by nouns (e.g., shape, 22 sound) in order to investigate the degree of segregation across sensory regions of these properties. Concerning the anatomy of the real-word size effect, previous literature has shown the implication of lateral-occipital, inferotemporal, and parahippocampal cortices (Konkle and Oliva, 2012;He et al, 2013). The discrepancy between those studies and the current one can be traced down to the numerous methodological differences:…”

“…When they did not use pictures, but words, as we do, they engaged subejcts in tasks involving active size comparison (He et al, 2013) or imagery of objets in their prototypical or atypical size (Konkle and Oliva, 2012 studies 3), thus drawing subject's attention on the size dimension. Instead, in our experiment, subjects were asked to actively think of the whole concept referred to by the words, with no specific focus on the size dimension;…”

“…Most studies used pictures as stimuli (Konkle and Oliva, 2012 studies 1 and 2), while we used words;…”

“…Beside this macroscopic parcellation based on categorical preference, other more abstract dimensions, such as animacy (Sha et al, 2014) and real world size (Konkle and Oliva, 2012) have been suggested as additional organizing principles of object processing in the ventral visual path. In our study we could retrieve size and category information from the activity of occipito-temporal areas, but only at the 25 multivariate level, indicating that the activation of this information during passive word reading is more subtle and distributed compared to that directly evoked by looking at the pictures of the stimuli.…”