Objects that promise rewards are prioritized for visual selection. The way this prioritization shapes sensory processing in visual cortex, however, is debated. It has been suggested that rewards motivate stronger attentional focusing, resulting in a modulation of sensory selection in early visual cortex. An open question is whether those reward-driven modulations would be independent of similar modulations indexing the selection of attended features that are not associated with reward. Here, we use magnetoencephalography in human observers to investigate whether the modulations indexing global color-based selection in visual cortex are separable for target- and (monetary) reward-defining colors. To assess the underlying global color-based activity modulation, we compare the event-related magnetic field response elicited by a color probe in the unattended hemifield drawn either in the target color, the reward color, both colors, or a neutral task-irrelevant color. To test whether target and reward relevance trigger separable modulations, we manipulate attention demands on target selection while keeping reward-defining experimental parameters constant. Replicating previous observations, we find that reward and target relevance produce almost indistinguishable gain modulations in ventral extratriate cortex contralateral to the unattended color probe. Importantly, increasing attention demands on target discrimination increases the response to the target-defining color, whereas the response to the rewarded color remains largely unchanged. These observations indicate that, although task relevance and reward influence the very same feature-selective area in extrastriate visual cortex, the associated modulations are largely independent.

When a stimulus is associated with a reward, it becomes prioritized, and the allocation of attention to that stimulus increases. For low-level features, such as color, this reward-based allocation of attention can manifest early in time and as a faster and stronger shift of attention to targets with that color, as reflected by the N2pc (a parieto-occipital electrophysiological component peaking at ∼250 msec). It is unknown, however, if reward associations can similarly modulate attentional shifts to complex objects or object categories, or if reward-related modulation of attentional allocation to such stimuli would occur later in time or through a different mechanism. Here, we used magnetoencephalographic recordings in 24 participants to investigate how object categories with a reward association would modulate the shift of attention. On each trial, two colored squares were presented, one in a target color and the other in a distractor color, each with an embedded object. Participants searched for the target-colored square and performed a corner discrimination task. The embedded objects were from either a rewarded or non-rewarded category, and if a rewarded-category object were present within the target-colored square, participants could earn extra money for correct performance. We observed that when the target color contained an object from a rewarded versus a non-rewarded category, the neural shift of attention to the target was faster and of greater magnitude, although the rewarded objects were not relevant for correct task performance. These results suggest that reward associations of complex objects can rapidly modulate attentional allocation to a target.

Little is known about the neural underpinnings of number word comprehension in young children. Here we investigated the neural processing of these words during the crucial developmental window in which children learn their meanings and asked whether such processing relies on the Approximate Number System. ERPs were recorded as 3- to 5-year-old children heard the words one, two, three, or six while looking at pictures of 1, 2, 3, or 6 objects. The auditory number word was incongruent with the number of visual objects on half the trials and congruent on the other half. Children's number word comprehension predicted their ERP incongruency effects. Specifically, children with the least number word knowledge did not show any ERP incongruency effects, whereas those with intermediate and high number word knowledge showed an enhanced, negative polarity incongruency response (N inc ) over centroparietal sites from 200 to 500 msec after the number word onset. This negativity was followed by an enhanced, positive polarity incongruency effect (P inc ) that emerged bilaterally over parietal sites at about 700 msec. Moreover, children with the most number word knowledge showed ratio dependence in the P inc (larger for greater compared with smaller numerical mismatches), a hallmark of the Approximate Number System. Importantly, a similar modulation of the P inc from 700 to 800 msec was found in children with intermediate number word knowledge. These results provide the first neural correlates of spoken number word comprehension in preschoolers and are consistent with the view that children map number words onto approximate number representations before they fully master the verbal count list.

Neuroimaging work on multisensory conflict suggests that the relevant modality receives enhanced processing in the face of incongruency. However, the degree of stimulus processing in the irrelevant modality and the temporal cascade of the attentional modulations in either the relevant or irrelevant modalities are unknown. Here, we employed an audiovisual conflict paradigm with a sensory probe in the task-irrelevant modality (vision) to gauge the attentional allocation to that modality. ERPs were recorded as participants attended to and discriminated spoken auditory letters while ignoring simultaneous bilateral visual letter stimuli that were either fully congruent, fully incongruent, or partially incongruent (one side incongruent, one congruent) with the auditory stimulation. Half of the audiovisual letter stimuli were followed 500–700 msec later by a bilateral visual probe stimulus. As expected, ERPs to the audiovisual stimuli showed an incongruency ERP effect (fully incongruent versus fully congruent) of an enhanced, centrally distributed, negative-polarity wave starting ∼250 msec. More critically here, the sensory ERP components to the visual probes were larger when they followed fully incongruent versus fully congruent multisensory stimuli, with these enhancements greatest on fully incongruent trials with the slowest RTs. In addition, on the slowest-response partially incongruent trials, the P2 sensory component to the visual probes was larger contralateral to the preceding incongruent visual stimulus. These data suggest that, in response to conflicting multisensory stimulus input, the initial cognitive effect is a capture of attention by the incongruent irrelevant-modality input, pulling neural processing resources toward that modality, resulting in rapid enhancement, rather than rapid suppression, of that input.

Brain imaging studies suggest that the rostrolateral prefrontal cortex (RLPFC), is involved in relational reasoning. Functional magnetic resonance imaging (fMRI) studies involving Raven's Progressive Matrices or verbal propositional analogies indicate that the RLPFC is engaged by tasks that require integration across multiple relational structures. Several studies have shown that the RLPFC is more active when people must evaluate an analogy (e.g., Is shoe to foot as glove is to hand?) than when they must simply evaluate two individual semantic relationships, consistent with the hypothesis that this region is important for relational integration. The current fMRI investigation further explores the role of the RLPFC in reasoning and relational integration by comparing RLPFC activation across four different propositional analogy conditions. Each of the four conditions required either relation completion (e.g., Shoe is to foot as glove is to WHAT? → “hand”) or relation comparison (e.g., Is shoe to foot as glove is to hand? → “yes”). The RLPFC was engaged more strongly by the comparison subtask relative to completion, suggesting that the RLPFC is particularly involved in comparing relational structures.