Abstract
Objects can be described in terms of low-level (e.g., boundaries) and high-level properties (e.g., object semantics). While recent behavioral findings suggest that the influence of semantic relatedness between objects on attentional allocation can be independent of task-relevance, the underlying neural substrate of semantic influences on attention remains ill-defined. Here, we employ behavioral and functional magnetic resonance imaging measures to uncover the mechanism by which semantic information increases visual processing efficiency. We demonstrate that the strength of the semantic relatedness signal decoded from the left inferior frontal gyrus: 1) influences attention, producing behavioral semantic benefits; 2) biases spatial attention maps in the intraparietal sulcus, subsequently modulating early visual cortex activity; and 3) directly predicts the magnitude of behavioral semantic benefit. Altogether, these results identify a specific mechanism driving task-independent semantic influences on attention.
Highlights
Objects can be described in terms of low-level and high-level properties
Examination of accuracy rates revealed that participants were significantly more accurate at identifying the target when it appeared on a SR object than when it appeared on a NR object, t(10) = 2.21, p = .052, Cohen’s d = .665 (Figure 2D)
These results are consistent with previous findings reported by our lab (Malcolm et al, 2016) as well as others (Cornelissen & Võ, 2017; Peacock et al, 2018), demonstrating that the task-irrelevant semantic relationship between objects influences attentional allocation
Summary
Retinotopic areas (V1, V2, V3) were defined using flashing checkerboard stimuli presented in a bowtie shape that flipped between blocks of vertical and horizontal meridians. Participants fixated on a central black fixation square that randomly dimmed to gray for variable durations. Participants were informed to hold down a button every time the black fixation square dimmed to gray and release it when black. An additional stimuli position localizer was conducted to Semantic influence on early visual cortex define the spatial locations (bottom left and bottom right) occupied by the objects in the experimental task and increase the selectivity of voxels. Flashing checkerboard stimuli (2.7 x 2.1 ) flickering at 5 Hz was presented in one of the three possible stimuli location (above fixation, lower-left, lowerright) for 12 s.
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