眼跳的双相调节理论的行为证据

为了研究眼跳的双相调节理论是否适用于人类的视觉系统,本研究测量了人类被试对分别呈现在三种眼跳时间段（基线、眼跳抑制和眼跳增强）内的光栅的朝向辨别准确率。研究发现：相对于光栅呈现在基线时间段内,被试对呈现在抑制（或增强）时间段内的光栅的朝向辨别准确率显著地更低（或更高）（实验1）;另外,只有使用低或中等空间频率光栅作为测试刺激时,才有这种双相调节作用（实验2）。这些结果表明：人类的视觉系统在眼跳过程中存在双相调节机制,并且这种双相调节机制具有刺激选择性。     

不同空间构型下邻近性对视觉工作记忆中相似性效应的影响

相似性对视觉工作记忆表征的促进被称为相似性效应。以相似项目间的距离和是否插入其他项目改变邻近性,并操纵记忆项空间构型有序性,探讨邻近性对相似性效应的影响。结果发现,不同空间构型和邻近性条件下相似项目的记忆正确率高于非相似项目;在空间构型有序下,相似项目距离远时,插入其他项目时的相似性效应值低于不插入,而空间构型无序下未发现显著差异。这表明相似性促进视觉工作记忆表征,空间构型在邻近性对相似性效应的影响中起重要作用。     

The Bright and Dark Sides of Performance-Dependent Monetary Rewards: Evidence From Visual Perception Tasks

Studies have shown that performance-dependent monetary rewards facilitate visual perception. However, no study has examined whether such a positive effect is limited to the rewarded task or may be generalized to other tasks. In the current study, two groups of people were asked to perform two visual perception tasks, one being a reward-relevant task and the other being a reward-irrelevant task. For the reward-relevant task, the experimental group received performance-dependent monetary rewards, whereas the control group did not. For the reward-irrelevant task, both groups were not rewarded. The two tasks were randomly intermixed trial by trial (Experiment 1) or presented block by block (Experiment 2) or session by session (Experiments 3a, 3b, and 3c). Results showed that performance-dependent monetary rewards improved participants' performance on the relevant task in all experiments and impaired their performance on the irrelevant task in Experiments 2, 3a, 3b, and 3c. These results suggested that monetary rewards might incur a cost on reward-irrelevant tasks. Finally, the benefit of monetary rewards disappeared when they were no longer provided during the final session. This is the first study that reveals both the bright and dark sides of the performance-dependent monetary rewards in visual perception.     

Working memory can compare two visual items without accessing visual consciousness

Recent studies argued that unconscious visual information could access the working memory, however, it is still unclear whether the central executive could be activated unconsciously. We investigated, using a delayed match-to-sample task, whether the central executive is an unconscious process. In the experiment of the present study, participants were asked to compare the locations of two given visual targets. Both targets (or one of the two targets, depending on the experimental condition) were masked by a visual masking paradigm. The results showed an above-chance-level performance even in the condition that participants compared two unconscious targets. However, when the trials with the non-visual conscious experience of the target were removed from the analysis, the performance was no longer significantly different from chance level. Our results suggest that the central executive could be activated unconsciously by some level of stimulus signal, that is still below the threshold for a subjective report.     

Neuronal correlates of full and partial visual conscious perception

Stimuli may induce only partial consciousness—an intermediate between null and full consciousness—where the presence but not identity of an object can be reported. The differences in the neuronal basis of full and partial consciousness are poorly understood. We investigated if evoked and oscillatory activity could dissociate full from partial conscious perception. We recorded human cortical activity with magnetoencephalography (MEG) during a visual perception task in which stimulus could be either partially or fully perceived. Partial consciousness was associated with an early increase in evoked activity and theta/low-alpha-band oscillations while full consciousness was also associated with late evoked activity and beta-band oscillations. Full from partial consciousness was dissociated by stronger evoked activity and late increase in theta oscillations that were localized to higher-order visual regions and posterior parietal and prefrontal cortices. Our results reveal both evoked activity and theta oscillations dissociate partial and full consciousness.     

Investigating route learning,metacognition, and beacon-based strategies using virtual environments

IntroductionDominant theories of wayfinding may have underestimated the ease with which adults can learn a route, even with minimal exposure to that route.ObjectivesIn this paper we present three different experiments to provide a comprehensive picture of whether adults can learn complex routes consisting of a number of choicepoints, and if so, what strategies they might be employing to do so.Methodand results We found that adults could learn a 15-junction route after only a single experience of the route (Experiment 1) but that they underestimated how good they would be at learning the 15-junction route (Experiment 2). In Experiment 3, we found that when learning a route made up of “T” shaped junctions, participants relied on a “beacon” strategy based on visual matching.ConclusionsCollectively, these findings suggest that adults can learn complex routes, even with as many as 15 choicepoints, very quickly and without the need for repeated exposure. These findings have implications for theories of wayfinding and call into question the need for repeated exposure.     

On-to-off-path gaze shift cancellations lead to gaze concentration in cognitively loaded car drivers: A simulator study exploring gaze patterns in relation to a cognitive task and the traffic environment

Appropriate visual behaviour is necessary for safe driving. Many previous studies have found that when performing non-visual cognitive tasks, drivers typically display an increased amount of on-path glances, along with a deteriorated visual scanning pattern towards potential hazards at locations outside their future travel path (off-path locations). This is often referred to as a gaze concentration effect. However, what has not been explored is more precisely how and when gaze concentration arises in relation to the cognitive task, and to what extent the timing of glances towards traffic-situation relevant off-path locations is affected. To investigate these specific topics, a driving simulator study was carried out. Car drivers’ visual behaviour during execution of a cognitive task (n-back) was studied during two traffic scenarios; one when driving through an intersection and one when passing a hidden exit. Aside from the expected gaze concentration effect, several novel findings that may explain this effect were observed. It was found that gaze shifts from an on-path to an off-path location were inhibited during increased cognitive load. However, gaze shifts in the other direction, that is, from an off-path to an on-path location, remained unaffected. This resulted in on-path glances increasing in duration, while off-path glances decreased in number. Furthermore, the inhibited off-path glances were typically not compensated for later. That is, off-path glances were cancelled, not delayed. This was the case both in relation to the cognitive task (near-term) and the traffic environment (far-term). There was thus a general reduction in the number of glances towards situationally relevant off-path locations, but the timing of the remaining glances was unaffected. These findings provide a deeper understanding of the mechanism behind gaze concentration and can contribute to both understanding and prediction of safety relevant effects of cognitive load in car drivers.     

Parts and wholes in person recognition: developmental trends

This study's aim is the investigation of short-term visual person recognition in 8- and 10-year-olds and adults, within the part-whole paradigm introduced by. Natural unfamiliar whole persons were contrasted with natural unfamiliar faces to test for differences between person processing and face processing. Two experiments showed advantages of whole face recognition over isolated face feature recognition. Also, these was a complete over part probe advantage (CPA, ) for person recognition in all age groups. Thus, recognition became more accurate between 8 years and adulthood, but no developmental shift in visual information processing was observable with face and whole person recognition. I conclude that person recognition does not rely on processes completely different from those of face recognition and that this holds for 8- and 10-year-olds as well as for adults.     

Anisotropic tracking: evidence for automatic synergy formation in a bimanual task

Investigation of interlimb synergy has become synonymous with the study of coordination dynamics and is largely confined to periodic movement. Based on a computational approach this paper demonstrates a method of investigating the formation of a novel synergy in the context of stochastic, spatially asymmetric movements. Nine right-handed participants performed a two degrees of freedom (2D) "etch-a-sketch" tracking task where the right hand controlled the horizontal position of the response cursor on the display while the left hand controlled the vertical position. In a pre-practice 2D tracking task, measures of phase lag between the irregularly moving target and the response showed that participants controlled left and right hands independently, performance of the right hand being slightly superior to the left. Participants then undertook 4 h 16 min distributed practice of a one degree of freedom etch-a-sketch task where the target was constrained to move irregularly in only the 45 degrees direction on the display. To track such a target accurately participants had to make in-phase coupled stochastic movements of the hands. In a post-practice 2D task, measures of phase lag showed anisotropic improvement in performance, the amount of improvement depending on the direction of motion on the display. Improvement was greatest in the practised 45 degrees and least in the orthogonal 135 degrees direction. Best and worst performances were no longer in the directions associated with right and left hands independently, but in directions requiring coupled movements of the two hands. These data support the proposal that the nervous system can establish a model of novel coupling between the hands and thereby form a task-dependent bimanual synergy for controlling the stochastic coupled movements as an entity.     

Attention capacity and task difficulty in visual search

When a visual search task is very difficult (as when a small feature difference defines the target), even detection of a unique element may be substantially slowed by increases in display set size. This has been attributed to the influence of attentional capacity limits. We examined the influence of attentional capacity limits on three kinds of search task: difficult feature search (with a subtle featural difference), difficult conjunction search, and spatial-configuration search. In all 3 tasks, each trial contained sixteen items, divided into two eight-item sets. The two sets were presented either successively or simultaneously. Comparison of accuracy in successive versus simultaneous presentations revealed that attentional capacity limitations are present only in the case of spatial-configuration search. While the other two types of task were inefficient (as reflected in steep search slopes), no capacity limitations were evident. We conclude that the difficulty of a visual search task affects search efficiency but does not necessarily introduce attentional capacity limits.