Abstract
While some visual objects prompt strong affective responses (e.g., guns and ice cream), most objects are thought to be affectively neutral. Last year we reported evidence for the existence of “micro-valences” (Lebrecht & Tarr, VSS, 2010): that nominally neutral objects actually possess subtle valences that we hypothesize form an integral part of object perception. In the current experiment we used fMRI to investigate: a) the extent to which micro-valences are coded within the extended visual object recognition network (Bar, 2007); b) how micro-valences are neurally instantiated with respect to valence strength and direction. Using slow event-related fMRI, participants viewed an object picture for 500ms and evaluated the object's “pleasantness” on each trial. Participants were shown 120 everyday, nominally neutral objects (e.g., teapots and clocks) and 120 strongly valenced objects (e.g., gold and a skull). Objects were assigned to these conditions based on mean valence ratings acquired in a prior experiment with a different population of participants. Individualized ratings for all objects were also acquired for our fMRI participants during a post-scan session. Regions of interest for further analysis were identified using two independent localizers: a) objects versus scrambled objects; b) strongly valenced objects versus minimally valenced objects (e.g., paperclips). Two results stand out. First, somewhat consistent with previous findings, lateral regions of PFC and regions of medial OFC are selective to a positive versus negative comparison for strongly valenced objects. Second, and intriguingly, almost all participants show selectivity for micro-valence objects, comparing positive to negative, in a region adjacent to the region for strongly valenced objects. We posit that intrinsic to visual object perception, object valence – for all objects – is evaluated in PFC. This valence metric forms one of many associated object properties that can influence subsequent perceptual and non-perceptual object-related processing.
Funding provided by the Perceptual Expertise Network (#15573-S6), a collaborative award from James S. McDonnell Foundation, by the Temporal Dynamics of Learning Center at UCSD (NSF Science of Learning Center SBE-0542013), and by an NIH EUREKA Award (#1R01MH084195-01) to MJT. NEI Vision Training Grant to SL.