It is well known that attentional capture by an irrelevant salient item is contingent on top-down feature selection, but whether attentional capture may be modulated by top-down spatial attention remains unclear. Here, we combined behavioral and ERP measurements to investigate the contribution of top-down spatial attention to attentional capture under modified spatial cueing paradigms. Each target stimulus was preceded by a peripheral circular cue array containing a spatially uninformative color singleton cue. We varied target sets but kept the cue array unchanged among different experimental conditions. When participants' task was to search for a colored letter in the target array that shared the same peripheral locations with the cue array, attentional capture by the peripheral color cue was reflected by both a behavioral spatial cueing effect and a cue-elicited N2pc component. When target arrays were presented more centrally, both the behavioral and N2pc effects were attenuated but still significant. The attenuated cue-elicited N2pc was found even when participants focused their attention on the fixed central location to identify a colored letter among an RSVP letter stream. By contrast, when participants were asked to identify an outlined or larger target, neither the behavioral spatial cueing effect nor the cue-elicited N2pc was observed, regardless of whether the target and cue arrays shared same locations or not. These results add to the evidence that attentional capture by salient stimuli is contingent upon feature-based task sets, and further indicate that top-down spatial attention is important but may not be necessary for contingent attentional capture.

In this study, we used high-density event-related potentials (ERPs) to investigate the brain mechanisms underlying behavioral specificity and generalization of short-term learning of texture discrimination task (TDT). Human adults were trained with TDT for a single session of 1.5 h and their ERPs were measured on the following day. Behavioral performance showed that, after a same amount of exposure of the trained and untrained conditions during EEG session, learning effects were specific to the trained background orientation but generalized across target locations. ERP data, however, revealed both target-location and background-orientation specific changes. While the behavioral background-orientation specificity mainly involved amplitude enhancement of early N2pc over occipital cortex, behavioral target-location generalization was associated with modulation of tempo-spatial configurations of the N2pc component (early-occipital vs. late-parietal/temporal pattern) and decrease of frontal P2 amplitudes for the trained relative to the untrained condition. The earliest visual component C1 did not show specific effects for either background orientation or target location. These results indicated different brain mechanisms underlying the behavioral specificity and generalization of TDT learning. Based on the present findings and literatures, we propose that perceptual learning may induce not only enhancement of relatively early visual selection of the trained target among distractors but also decreases of top-down attention originating from high-level brain center. The reactivation of top-down attention control in some conditions (e.g., the untrained target-location condition) may compensate for the specific effect induced by the early visual selective attention mechanism, leading to generalization or less specificity of perceptual learning in behavioral performance.

Sequence learning is a ubiquitous facet of human and animal cognition. Here, using a common sequence reproduction task, we investigated whether and how the ordinal and relational structures linking consecutive elements are acquired by human adults, children, and macaque monkeys. While children and monkeys exhibited significantly lower precision than adults for spatial location and temporal order information, only monkeys appeared to exceedingly focus on the first item. Most importantly, only humans, regardless of age, spontaneously extracted the spatial relations between consecutive items and used a chunking strategy to compress sequences in working memory. Monkeys did not detect such relational structures, even after extensive training. Monkey behavior was captured by a conjunctive coding model, whereas a chunk-based conjunctive model explained more variance in humans. These age-and species-related differences are indicative of developmental and evolutionary mechanisms of sequence encoding and may provide novel insights into the uniquely human cognitive capacities.

To our knowledge, the present studies are the first to discover a relatively strong correlation between IOR-OT and cognitive functions in older adults. These findings provide new evidence supporting the inhibition deficit theory of aging and lay the foundation of using IOR-OT as an objective measure of cognitive functions in the aging population.