View-invariant object category learning, recognition, and search: how spatial and object attention are coordinated using surface-based attentional shrouds

How does the brain learn to recognize an object from multiple viewpoints while scanning a scene with eye movements? How does the brain avoid the problem of erroneously classifying parts of different objects together? How are attention and eye movements intelligently coordinated to facilitate object learning? A neural model provides a unified mechanistic explanation of how spatial and object attention work together to search a scene and learn what is in it. The ARTSCAN model predicts how an object's surface representation generates a form-fitting distribution of spatial attention, or "attentional shroud". All surface representations dynamically compete for spatial attention to form a shroud. The winning shroud persists during active scanning of the object. The shroud maintains sustained activity of an emerging view-invariant category representation while multiple view-specific category representations are learned and are linked through associative learning to the view-invariant object category. The shroud also helps to restrict scanning eye movements to salient features on the attended object. Object attention plays a role in controlling and stabilizing the learning of view-specific object categories. Spatial attention hereby coordinates the deployment of object attention during object category learning. Shroud collapse releases a reset signal that inhibits the active view-invariant category in the What cortical processing stream. Then a new shroud, corresponding to a different object, forms in the Where cortical processing stream, and search using attention shifts and eye movements continues to learn new objects throughout a scene. The model mechanistically clarifies basic properties of attention shifts (engage, move, disengage) and inhibition of return. It simulates human reaction time data about object-based spatial attention shifts, and learns with 98.1% accuracy and a compression of 430 on a letter database whose letters vary in size, position, and orientation. The model provides a powerful framework for unifying many data about spatial and object attention, and their interactions during perception, cognition, and action.     

The attentional blink unveils the interplay between conscious perception,spatial attention and working memory encoding

Our ability to perceive two events in close temporal succession is severely limited, a phenomenon known as the attentional blink. While the blink has served as a popular tool to prevent conscious perception, there is less research on its causes, and in particular on the role of conscious perception of the first event in triggering it. In three experiments, we disentangled the roles of spatial attention, conscious perception and working memory (WM) in causing the blink. We show that while allocating spatial attention to T1 is neither necessary nor sufficient for eliciting a blink, consciously perceiving it is necessary but not sufficient. When T1 was task irrelevant, consciously perceiving it triggered a blink only when it matched the attentional set for T2. We conclude that consciously perceiving a task-relevant event causes the blink, possibly because it triggers encoding of this event into WM. We discuss the implications of these findings for the relationship between spatial attention, conscious perception and WM, as well as for the distinction between access and phenomenal consciousness.     

Attentional bias to angry faces using the dot-probe task? It depends when you look for it

A number of studies using the dot-probe task now report the existence of an attentional bias to angry faces in participants who rate highly on scales of anxiety; however, no equivalent bias has been observed in non-anxious populations, despite evidence to the contrary from studies using other tasks. One reason for this discrepancy may be that researchers using the dot-probe task have rarely investigated any effects which might emerge earlier than 500 ms following presentation of the threat-related faces. Accordingly, in the current study we presented pairs of face stimuli with emotional and neutral expressions and probed the allocation of attention to these stimuli for presentation times of 100 and 500 ms. Results showed that at 100 ms there was an attentional bias towards the location of the relatively threatening stimulus (the angry face in angry/neutral pairs and the neutral face in neutral/happy pairs) and this pattern reversed by 500 ms. Comparisons of reaction time (RT) scores with an appropriate baseline suggested that the early bias toward threatening faces may actually arise through inhibition of the relatively least threatening member of a face pair rather than through facilitation of, or vigilance towards, the more threatening stimulus. However the mechanisms governing the observed biases are interpreted, these data provide evidence that probing for the location of spatial attention at 500 ms is not necessarily indicative of the initial allocation of attention between competing emotional facial stimuli.     

Modality-repetition and attentional effects on reflex blinking in infants and adults

The ability of a brief prepulse to inhibit reflexively elicited startle is a robust phenomenon in adults of several species but is weak or absent in infants. The possibility that afferent processing of the prepulse is inadequate in infants was tested by assessing the integrity of two other types of reflex modulation that occur in modality-specific paths, that is, attenuation by repetition of same-modality stimuli and enhancement by modality-selective attention. The reflex, measured by electromyographic activity of the muscle controlling blink, was elicited by intense light flashes or noise bursts preceded by brief acoustic or visual prepulses and delivered during attention-directing acoustic or visual foregrounds that evoked cardiac deceleration. Modality-repetition effects were evidenced by smaller peak blink magnitude and longer latency of blinking to same than to different modality pairs and did not differ as a function of age (4-month-old infants or college students). Attention effects were also seen in both infants and adults and, in accord with previous findings, were evident in magnitude for infants and latency for adults. Thus, immaturity in paths mediating these effects could not explain delayed development of prepulse inhibition. Other possibilities include delayed maturation of extrinsic inhibition or of transient-processing systems.     

注意瞬脱的瓶颈理论

综述了注意瞬脱的瓶颈理论的相关研究。主要包括：（1）高级中枢加工瓶颈形成的两阶段模型、中枢干扰理论、TLC假设和注意的延迟投入假设;（2）目标选择的控制瓶颈形成的输入过滤器与目标模板假说;（3）同时类型系列标记模型。最后从瓶颈理论在整个注意瞬脱理论中的片面性和注意瞬脱的瓶颈理论本身的不完善性两方面剖析了瓶颈理论的局限性     

The attentional blink reveals sluggish attentional shifting in adolescents with specific language impairment

Rapid processing deficits have been the subject of much debate in the literature on specific language impairment (SLI). Hari and Renvall (2001) [Hari, R. & Renvall, H. (2001). Impaired processing of rapid stimulus sequences in dyslexia. Trends in cognitive sciences, 5, 525-532.] proposed that the source of this deficit can be attributed to sluggish attentional shifting abilities. That is, more time is required to shift attention between stimuli. To test this claim, 26 adolescents with SLI (divided into two subgroups to control for differences in non-verbal intelligence) and 14 controls were presented with a rapid serial visual presentation task. In this task participants were asked to detect two visual targets presented serially with distracter items with varying inter-target intervals (i.e., time difference between targets). This task was designed to elicit an attentional blink (AB). The AB describes the phenomenon whereby non-impaired individuals are less likely to report the second of two targets presented within 200-500ms of each other. After controlling for group differences in non-verbal intelligence, the SLI group was found to be significantly less accurate than the control group at successfully reporting the second target at inter-target intervals of 100, 200, 300, 400 and 800ms. The results were interpreted to suggest that adolescents with language impairments have an AB which differs from non-impaired individuals in both magnitude and duration.     

Examining the relationships between self‐efficacy,task‐relevant attentional control,and task performance: Evidence from event‐related brain potentials

Self‐efficacy (SE) is a modifiable psychosocial factor related to individuals’ beliefs in their capabilities to successfully complete courses of action and has been shown to be positively associated with task performance. The authors hypothesized that one means through which SE is related with improved performance is through enhanced task‐relevant attentional control during task execution. To assess this hypothesis, we examined the relationships between SE and behavioural and neural indices of task performance and task‐relevant attentional control for 76 young adults during the completion of a flanker task. Results showed that greater SE was associated with greater response accuracy and P3b amplitude across task conditions, and faster RT under more difficult task conditions. Additionally, P3b amplitude was found to mediate the relationship between SE and task performance in the difficult condition. These findings suggest that greater attentional allocation to task‐relevant processes, including monitoring stimulus‐response relationships and focusing attention on working memory operations, may help explain the association between SE and improved task performance.     

Limited generalisation of changes in attentional bias following attentional bias modification with the visual probe task

Although attentional bias modification (ABM) can change anxiety, recent studies failed to replicate such effects, possibly because the visual probe ABM failed to induce changes in attentional bias (AB). We investigated whether visual probe ABM generalised to different measures of AB besides the visual probe task (VPT), and thus whether ABM genuinely changes attentional processing. We trained participants (N?=?60) to either attend towards or away from angry facial expressions, and we examined training effects on the dot probe task, the exogenous cueing task, and the visual search task. We found a small change in AB in the VPT, but this effect did not transfer to the exogenous cueing task or the visual search task. Our study shows that ABM does not necessarily lead to generalised effects on AB. This finding can be explained by the poor psychometric properties of the AB measures.     

Self-referential schemas and attentional bias predict severity and naturalistic course of depression symptoms

Attentional bias and self-referential schemas have been observed in numerous cross-sectional studies of depressed adults and are theorised to maintain negative mood. However, few longitudinal studies have examined whether maladaptive cognition predicts the course of depressive symptoms. Fifty-seven adults with elevated depression symptoms were assessed for negative attentional bias using a dot-probe task with eye-tracking and self-referential schemas using a self-referent encoding task. Participants subsequently completed five weekly depression symptom assessments. Participants with more negative self-referential schemas had higher baseline depression symptoms (r?=?.55). However, participants who spent more time attending to negative words showed greater symptom worsening over time (r?=?.42). The findings for negative self-referential schemas replicate past research, while the findings for negative attention bias represent the first evidence showing that attentional biases predict naturalistic symptom course. This work suggests that negative attention biases maintain depression symptoms and represent an important treatment target for neurocognitive therapeutics.     

Individual differences in anxiety and executive functioning: A multidimensional view

The relationship between individual differences in anxiety and executive functioning was investigated in a sample of young adults. Verbal and spatial working memory, resistance to interference, negative priming, and task‐switching measures were used to assess three executive functioning dimensions: updating, inhibition, and shifting. An additional index of basic psychomotor speed was added to this cognitive battery. According to the multidimensional interaction model of anxiety proposed by Endler (1997), state (cognitive–worry and autonomic–emotional) and trait (related to social evaluation, physical danger, ambiguous situations, and daily routines) anxiety were assessed in this evaluation context. Results indicated that shifting and inhibition (negative priming) efficiency were negatively related to state (cognitive–worry) and trait (related to social evaluation) anxiety. However, there was a relative advantage of subjects higher in social evaluation apprehensions in their memory updating performance. The results are consistent with several predictions of the attentional control theory (Eysenck, Derakshan, Santos, & Calvo, 2007), and are relevant for research regarding the interaction of situational, personality, and cognitive functioning dimensions.