Early, but no late ERP signature of auditory awareness in cross-modal distractor-induced deafness

Previous research showed that dual-task processes such as the attentional blink are not always transferable from unimodal to cross-modal settings. Here we ask whether such a transfer can be stated for a distractor-induced impairment of target detection, which has been established in vision (distractor-induced blindness, DIB) and was recently observed in the auditory modality (distractor-induced deafness, DID). The current study aimed to replicate the phenomenon in a cross-modal set up. An auditory target indicated by a visual cue should be detected, while task-irrelevant auditory distractors appearing before the cue had to be ignored. Behavioral data confirmed a cross-modal distractor-induced deafness: target detection was significantly reduced if multiple distractors preceded the target. Event-related brain potentials (ERPs) were used to identify the process crucial for target detection. ERPs revealed that successful target report was indicated by a larger frontal negativity around 200 ms. The same signature of target awareness has been previously observed in the auditory modality. In contrast to unimodal findings, P3 amplitude was not enhanced in case of an upcoming hit. Our results add to recent evidence that an early frontal attentional process is linked to auditory awareness, whereas the P3 is apparently not a consistent indicator of target access.

Saliency-based Rhythmic Coordination of Perceptual Predictions

Objects, shown explicitly or held in mind internally, compete for limited processing resources. Recent studies have demonstrated that attention samples locations and objects rhythmically. Interestingly, periodic sampling not only operates over objects in the same scene but also occurs for multiple perceptual predictions that are held in attention for incoming inputs. However, how the brain coordinates perceptual predictions that are endowed with different levels of bottom–up saliency information remains unclear. To address the issue, we used a fine-grained behavioral measurement to investigate the temporal dynamics of processing of high- and low-salient visual stimuli, which have equal possibility to occur within experimental blocks. We demonstrate that perceptual predictions associated with different levels of saliency are organized via a theta-band rhythmic course and are optimally processed in different phases within each theta-band cycle. Meanwhile, when the high- and low-salient stimuli are presented in separate blocks and thus not competing with each other, the periodic behavioral profile is no longer present. In summary, our findings suggest that attention samples and coordinates multiple perceptual predictions through a theta-band rhythm according to their relative saliency. Our results, in combination with previous studies, advocate the rhythmic nature of attentional process.

Pre-saccadic remapping relies on dynamics of spatial attention

SummaryEach eye movement shifts the projections of the visual scene on the retina. It has been proposed that the receptive fields of neurons in oculomotor areas are remapped pre-saccadically to account for these shifts. While remapping of the whole visual scene seems prohibitively complex, selection by visual attention may limit these processes to a subset of attended locations. Because attentional selection consumes time, remapping of attended locations should evolve in time, too. In our study, we cued a spatial location by presenting an attention capturing cue at different times before a saccade and constructed detailed maps of attentional allocation across the visual field. We observed no remapping when the cue appeared shortly before saccade. In contrast, when the cue appeared sufficiently early before saccade, attentional resources were reallocated to the remapped location. Our results suggest that pre-saccadic remapping is an attentional process relying on the spatial and temporal dynamics of visual attention.

Selective attention in pigeon temporal discrimination

Cues can vary in how informative they are about when specific outcomes, such as food availability, will occur. This study was an experimental investigation of the functional relation between cue informativeness and temporal discrimination in a peak-interval (PI) procedure. Each session consisted of fixed-interval (FI) 2- and 4-s schedules of food and occasional, 12-s PI trials during which pecks had no programmed consequences. Across conditions, the phi (ϕ) correlation between key light color and FI schedule value was manipulated. Red and green key lights signaled the onset of either or both FI schedules. Different colors were either predictive (ϕ = 1), moderately predictive (ϕ = 0.2-0.8) or not predictive (ϕ = 0) of a specific FI schedule. This study tested the hypothesis that temporal discrimination is a function of the momentary conditional probability of food; that is, pigeons peck the most at either 2 s or 4 s when ϕ = 1 and peck at both intervals when ϕ < 1. Response distributions were bimodal Gaussian curves; distributions from red- and green-key PI trials converged when ϕ ≤ 0.6. Peak times estimated by summed Gaussian functions, averaged across conditions and pigeons, were 1.85 and 3.87 s; however, pigeons did not always maximize the momentary probability of food. When key light color was highly correlated with FI schedules (ϕ ≥ 0.6), estimates of peak times indicated that temporal discrimination accuracy was reduced at the unlikely interval, but not the likely interval. The mechanism of this reduced temporal discrimination accuracy could be interpreted as an attentional process.