From Perception to Conception: How Meaningful Objects Are Processed over Time

Abstract

To recognize visual objects, our sensory perceptions are transformed through dynamic neural interactions into meaningful representations of the world but exactly how visual inputs invoke object meaning remains unclear. To address this issue, we apply a regression approach to magnetoencephalography data, modeling perceptual and conceptual variables. Key conceptual measures were derived from semantic feature--based models claiming shared features (e.g., has eyes) provide broad category information, while distinctive features (e.g., has a hump) are additionally required for more specific object identification. Our results show initial perceptual effects in visual cortex that are rapidly followed by semantic feature effects throughout ventral temporal cortex within the first 120 ms. Moreover, these early semantic effects reflect shared semantic feature information supporting coarse categorytype distinctions. Post-200 ms, we observed the effects along the extent of ventral temporal cortex for both shared and distinctive features, which together allow for conceptual differentiation and object identification. By relating spatiotemporal neural activity to statistical feature--based measures of semantic knowledge, we demonstrate that qualitatively different kinds of perceptual and semantic information are extracted from visual objects over time, with rapid activation of shared object features followed by concomitant activation of distinctive features that together enable meaningful visual object recognition.

Interactions between visual and semantic processing during object recognition revealed by modulatory effects of age of acquisition

“…An alternative possibility is that differences in the quality and richness of early-compared with later-acquired semantic representations (Belke et al, 2005;Brysbaert et al, 2000;Steyvers and Tenenbaum, 2005) are reflected in activation of greater numbers of anterior temporal neurons and synapses, resulting in a stronger neuromagnetic response. In either case we note that the time period in which we observed modulation of the semantic response in left anterior temporal cortex by AoA overlaps with the period in which Clarke et al (2011Clarke et al ( , 2013 reported stronger activation of medial left anterior temporal cortex by basic than domain level naming and a modulation of responses at the same site by distinctiveness. It also overlaps with period that Bemis and Pylkkänen (2011) associated with the process of integrating the meanings of pairs of words.…”

“…That said, Laaksonen et al (2012) reported induced ("rhythmic") activity at both 7-12 Hz and 17-22 Hz in left superior temporal regions during overt and covert object naming that extended down to the temporal pole. Clarke et al (2011) reported an evoked response from left medial anterior temporal cortex that was stronger during basic than domain level object naming from ~ 125 to 300 ms. Clarke et al (2013) left anterior temporal region from 84 to 120 ms and again from 170 to 210 ms. We also note that Bemis and Pylkkänen (2011) reported a period from ~ 185 to 255 ms during which MEG activity in left anterior temporal cortex was associated with combining the meanings of two words (e.g., red and boat) to decide whether or not they matched a simultaLog name frequency (Celex) (Baayen et al, 1993) Log name frequency (WFG) (Zeno et al, 1995) neously presented picture. Taken together, these studies indicate that it is possible to detect MEG responses originating in anterior temporal cortex and that those responses may be sensitive to semantic factors and semantic manipulations within the first 300 ms following stimulus presentation.…”

“…A related study by Clarke et al (2013) took a different approach to analyzing interactions between visual and semantic regions during object naming. They investigated the effects of typicality (or distinctiveness) of objects measured in terms of the number of features an object shares with other objects (cf.…”

“…When Bookheimer et al (2005) compared overt with covert object naming, they found very similar activation patterns except in regions associated with motor activity. Some previous MEG studies of object naming have used overt naming (Clarke et al, 2011(Clarke et al, , 2013Sörös et al, 2003;Vihla et al, 2006) while others have used passive viewing (Maratos et al, 2007), covert naming (Liljeström et al, 2009) or delayed overt naming in an effort to minimize mouth movement artifacts. Covert naming has been used in studies of visual word recognition for similar reasons (e.g., Wheat et al, 2010;Woodhead et al, 2011).…”

“…If the modulation of occipital activity by AoA observed by Ellis et al (2006) is a result of top-down re-activation of visual cortex by semantic processing (Clarke et al, 2011(Clarke et al, , 2013, then the modulatory effects of AoA on occipital activity would be expected to follow the modulatory effects on anterior temporal activity.…”