The time course of attentional bias to cues of threat and safety

It is well known that relative to neutral stimuli, attention is biased towards processing stimuli that convey threat. In a previous study in which a particular stimulus (e.g. a blue diamond) was associated with the delivery of an electrical shock, the presence of the fear-conditioned stimulus interfered with the execution of voluntary eye movements to other locations. Here, we show that this effect not only occurs early in time, but remains present long after the fear-conditioned stimulus was removed from the screen. In a subsequent experiment, we associated the presence of a particular stimulus with safety, that is, when this stimulus was present it was certain that no electrical shock would be delivered. The presence of the safety signalling stimulus also interfered with the execution of voluntary saccades, but only when the time between stimulus and cue presentation was relatively long. The results indicate that both signals of threat and signals of safety interfere with execution of a saccade long after the source of threat or safety has been removed. However, only threatening stimuli affect saccade execution early in time, suggesting that threatening stimuli drive selection exogenously.     

Spatial But Not Oculomotor Information Biases Perceptual Memory: Evidence From Face Perception and Cognitive Modeling

Recent research put forward the hypothesis that eye movements are integrated in memory representations and are reactivated when later recalled. However, “looking back to nothing” during recall might be a consequence of spatial memory retrieval. Here, we aimed at distinguishing between the effect of spatial and oculomotor information on perceptual memory. Participants’ task was to judge whether a morph looked rather like the first or second previously presented face. Crucially, faces and morphs were presented in a way that the morph reactivated oculomotor and/or spatial information associated with one of the previously encoded faces. Perceptual face memory was largely influenced by these manipulations. We considered a simple computational model with an excellent match (4.3% error) that expresses these biases as a linear combination of recency, saccade, and location. Surprisingly, saccades did not play a role. The results suggest that spatial and temporal rather than oculomotor information biases perceptual face memory.     

The effect of attending to motor overflow on its voluntary inhibition in young and older adults

Motor overflow refers to involuntary movement or muscle activity coinciding with voluntary movement. We examined whether 16 young adults (18-30 years) and 16 older adults (50-80 years) could voluntarily inhibit overflow. Participants performed a finger pressing task, exerting 50% of their maximal force. Overflow was concurrently recorded in the non-task hand. In the first condition, participants were not made aware of their motor overflow. Then participants, though informed of it, were asked to ignore their overflow. Finally, participants were requested to inhibit overflow with, and then without visual feedback, or vice versa. Overflow was exacerbated when older adults were unaware of it, and was reduced once they were informed. For young adults there was no significant difference between these conditions. Both Age Groups could significantly reduce overflow when so requested, independent of visual feedback. Thus motor overflow can be modulated by higher order cognitive control with directed attention.     

Increased saccadic rate during smooth pursuit eye movements in patients at Ultra High Risk for developing a psychosis

Abnormalities in eye tracking are consistently observed in schizophrenia patients and their relatives and have been proposed as an endophenotype of the disease. The aim of this study was to investigate the performance of patients at Ultra High Risk (UHR) for developing psychosis on a task of smooth pursuit eye movement (SPEM). Forty-six UHR patients and twenty-eight age and education matched controls were assessed with a task of SPEM and psychiatric questionnaires. Our results showed that both the corrective and non-corrective saccadic rates during pursuit were higher in the UHR group. There were however no differences in smooth pursuit gain between the two groups. The saccadic rate was related to positive UHR symptoms. Our findings indicate that abnormalities in SPEM are already present in UHR patients, prior to a first psychotic episode. These abnormalities occur only in the saccadic system.     

Why do we move our eyes while trying to remember? The relationship between non-visual gaze patterns and memory

Non-visual gaze patterns (NVGPs) involve saccades and fixations that spontaneously occur in cognitive activities that are not ostensibly visual. While reasons for their appearance remain obscure, convergent empirical evidence suggests that NVGPs change according to processing requirements of tasks. We examined NVPGs in tasks with long-term memory (LTM) and working memory (WM) requirements. Experiment 1 yielded significantly higher eye movement rate (EMR) in tasks requiring LTM search than in a WM task requiring maintenance of information. Experiment 2 manipulated accessibility of items in study-test episodic tasks using the levels of processing paradigm. EMR was high in episodic recall irrespective of item accessibility. Experiment 3 examined functional significance of saccades in LTM tasks. Voluntary saccadic suppression produced no evidence that saccades contribute to task performance. We discuss the apparent epiphenomenal nature of spontaneous saccades from an evolutionary perspective and outline a neuroanatomical model of the link between the saccadic and memory system.     

4~7岁儿童汉字正字法意识的发展

本研究采用两项实验考察学龄前儿童正字法意识的发展情况。实验1选取146名4~7岁儿童被试,要求其在计算机上完成词汇判断任务,刺激材料分为部件错误非字,部件位置错误非字,假字和真字。结果显示：大班在两项非字条件上的正确率均显著高于假字,而小班各条件差异均不显著;中班在部件位置错误非字上的正确率显著高于假字。表明学龄前儿童的正字法意识已经开始逐渐发展,且部件位置意识比部件意识容易获得。实验2采用Tobii T120型眼动仪,记录24名大班儿童在词汇判断（同实验1）过程中对刺激项目关注的眼动行为,从实时加工的过程探讨学龄前儿童正字法意识的发展。结果显示：儿童对部件错误非字/部件位置错误非字的目标部件的晚期关注程度显著高于假字,有力地证明：学龄前大班儿童已经具有部件和部件位置的意识。     

词切分对日-汉和汉-日双语者日语阅读影响的眼动研究*

选取24名日-汉和24名汉-日双语者,采用EyeLink2000眼动仪,探讨日-汉和汉-日双语者阅读有词切分线索的日语文本的眼动特征,研究词切分线索对日-汉和汉-日双语者日语句子阅读的影响。研究包括两个实验。实验一采用三种词切分方式：正常条件、词间空格条件和非词条件。为了确保三种词切分条件下句子的空间分布一致,实验二采用灰条标记作为词或非词的边界。结果表明,日语文本中加入词间空格促进汉-日双语者日语文本的阅读。     

句子语境中汉语词汇识别的即时加工过程

视觉词汇的认知加工及语境对这一过程的影响是心理语言学和认知心理学研究的热点。本研究采用眼动方法与ERP技术相结合的手段,考察了句子语境中汉语词汇识别的加工过程。通过六个实验, 探讨了不同限制性语境中汉语词汇形、音的作用及作用的脑机制, 不同偏向性语境对词汇歧义消解的影响及词汇歧义消解的脑机制。该研究结果揭示了句子语境对汉语词汇识别的影响, 提供了眼动方法和ERP技术相结合考察语言认知的研究范例。     

大学生英语语篇重复阅读的眼动研究

采用眼动追踪技术,考察重复阅读对母语为汉语的大学生阅读英语语篇的作用。研究采用2（目标词词频：高频、低频）×5（阅读遍数：1遍、2遍、3遍、4遍、5遍）的两因素被试内设计。结果发现：（1）随着阅读遍数的增加,读者的阅读理解正确率呈上升趋势,总阅读时间、注视次数、回视次数和平均注视时间显著降低,平均眼跳幅度显著增加;（2）阅读遍数与目标词词频的交互作用显著,表现为重复阅读对低频词识别的促进作用要显著大于对高频词识别的促进作用。研究表明重复阅读能够有效提高大学生对英语语篇的阅读效率。     

Pharmacological treatment effects on eye movement control

The increasing use of eye movement paradigms to assess the functional integrity of brain systems involved in sensorimotor and cognitive processing in clinical disorders requires greater attention to effects of pharmacological treatments on these systems. This is needed to better differentiate disease and medication effects in clinical samples, to learn about neurochemical systems relevant for identified disturbances, and to facilitate identification of oculomotor biomarkers of pharmacological effects. In this review, studies of pharmacologic treatment effects on eye movements in healthy individuals are summarized and the sensitivity of eye movements to a variety of pharmacological manipulations is established. Primary findings from these studies of healthy individuals involving mainly acute effects indicate that: (i) the most consistent finding across several classes of drugs, including benzodiazepines, first- and second- generation antipsychotics, anticholinergic agents, and anticonvulsant/mood stabilizing medications is a decrease in saccade and smooth pursuit velocity (or increase in saccades during pursuit); (ii) these oculomotor effects largely reflect the general sedating effects of these medications on central nervous system functioning and are often dose-dependent; (iii) in many cases changes in oculomotor functioning are more sensitive indicators of pharmacological effects than other measures; and (iv) other agents, including the antidepressant class of serotonergic reuptake inhibitors, direct serotonergic agonists, and stimulants including amphetamine and nicotine, do not appear to adversely impact oculomotor functions in healthy individuals and may well enhance aspects of saccade and pursuit performance. Pharmacological treatment effects on eye movements across several clinical disorders including schizophrenia, affective disorders, attention deficit hyperactivity disorder, Parkinson’s disease, and Huntington’s disease are also reviewed. While greater recognition and investigation into pharmacological treatment effects in these disorders is needed, both beneficial and adverse drug effects are identified. This raises the important caveat for oculomotor studies of neuropsychiatric disorders that performance differences from healthy individuals cannot be attributed to illness effects alone. In final sections of this review, studies are presented that illustrate the utility of eye movements for use as potential biomarkers in pharmacodynamic and pharmacogenetic studies. While more systematic studies are needed, we conclude that eye movement measurements hold significant promise as tools to investigate treatment effects on cognitive and sensorimotor processes in clinical populations and that their use may be helpful in speeding the drug development pathway for drugs targeting specific neural systems and in individualizing pharmacological treatments.