Aging and guided visual search: the role of visual working memory

In the present study, we examined age-related differences in utilizing learned associations to guide visual search. Participants viewed an object cue that was associated with 1 or 2 target colors, followed by a search array. Older adults showed slower RTs, larger visual search slopes, and reduced cue–target association knowledge than did younger adults. We also found increased search RTs and higher error rates when the cue was associated with 2 colors instead of 1. However, visual search slopes did not vary with the number of associated colors. This indicates that participants could activate multiple templates simultaneously to guide the search or retrieve associative information directly from the long-term memory. Furthermore, regression analyses showed that VWMC can predict both visual search performances and cue–target association knowledge. More broadly, our results demonstrate that VWMC can modify the effects of age on cued visual search performance.     

Does prism adaptation affect visual search in spatial neglect patients: A systematic review

Prism adaptation (PA) is a widely used intervention for (visuo‐)spatial neglect. PA‐induced improvements can be assessed by visual search tasks. It remains unclear which outcome measures are the most sensitive for the effects of PA in neglect. In this review, we aimed to evaluate PA effects on visual search measures. A systematic literature search was completed regarding PA intervention studies focusing on patients with neglect using visual search tasks. Information about study content and effectiveness was extracted. Out of 403 identified studies, 30 met the inclusion criteria. The quality of the studies was evaluated: Rankings were moderate‐to‐high for 7, and low for 23 studies. As feature search was only performed by five studies, low‐to‐moderate ranking, we were limited in drawing firm conclusions about the PA effect on feature search. All moderate‐to‐high‐ranking studies investigated cancellation by measuring only omissions or hits. These studies found an overall improvement after PA. Measuring perseverations and total task duration provides more specific information about visual search. The two (low ranking) studies that measured this found an improvement after PA on perseverations and duration (while accuracy improved for one study and remained the same for the other). This review suggests there is an overall effect of PA on visual search, although complex visual search tasks and specific visual search measures are lacking. Suggestions for search measures that give insight in subcomponents of visual search are provided for future studies, such as perseverations, search path intersections, search consistency and using a speed–accuracy trade‐off.     

彩色背景下的颜色突显研究

颜色突显是指在与视觉搜索任务有关的视觉显示中,采用颜色突出显示多个项目中的目标项目,从而提高视觉搜索效率的一种方法或技术。本文采用视觉搜索任务,以正确率和反应时为指标对单彩色和复杂彩色背景下不同颜色突显的视觉搜索绩效进行了研究。结果表明：（1）在单彩色背景和复杂彩色背景下,颜色突显条件视觉搜索绩效显著优于非突显条件;（2）在浅蓝或浅绿的单彩色背景下,四种颜色突显绩效中,红色突显绩效最好,紫色最差,而在随机彩色背景和复杂彩色背景下,颜色突显绩效差异并不显著;（3）在彩色背景下的颜色突显绩效会受到干扰数字的颜色的影响,其中在单色和随机彩色背景下,干扰目标颜色为黑色时的视觉搜索绩效优于干扰目标颜色为白色时的情景,而在自然彩色背景下,这种视觉搜索优势并不存在。     

Driving simulator validation with hazard perception

How should we assess the comparability of driving on a road and “driving” in a simulator? If similar patterns of behaviour are observed, with similar differences between individuals, then we can conclude that driving in the simulator will deliver representative results and the advantages of simulators (controlled environments, hazardous situations) can be appreciated. To evaluate a driving simulator here we compare hazard detection while driving on roads, while watching short film clips recorded from a vehicle moving through traffic, and while driving through a simulated city in a fully instrumented fixed-base simulator with a 90 degree forward view (plus mirrors) that is under the speed/direction control of the driver. In all three situations we find increased scanning by more experienced and especially professional drivers, and earlier eye fixations on hazardous objects for experienced drivers. This comparability encourages the use of simulators in drivers training and testing.     

The detection of temporally defined objects does not require focused attention

Perceptual grouping is crucial to distinguish objects from their background. Recent studies have shown that observers can detect an object that does not have any unique qualities other than unique temporal properties. A crucial question is whether focused attention is needed for this type of grouping. In two visual search experiments, we show that searching for an object defined by temporal grouping can occur in parallel. These findings suggest that focused attention is not needed for temporal grouping to occur. It is proposed that temporal grouping may occur because the neurons representing the changing object elements adopt firing frequencies that cause the visual system to bind these elements together without the need for focused attention.     

Contextual constraint and N + 2 preview effects in reading

Extracting linguistic information from locations beyond the currently fixated word is a core component of skilled reading. Recent debate on this topic is focused on the question of whether useful linguistic information can be extracted from more than one (parafoveally visible) word to the right of a fixated word (N). The current study examined this issue through the use parafoveal previews with a short and high-frequency next (N?+?1) word, as this should increase the opportunity for the extraction of useful information from the subsequent (N?+?2) word. Pairs of N?+?2 words were selected so that contextual constraint was either high or low. Using saccade contingent display manipulations, preview of a N?+?2 target word during word N viewing consisted of either a visually dissimilar nonword or a word. The results revealed a substantial drop in fixation probability for word N?+?1 when the N?+?2 preview was masked with a nonword. Furthermore, the masking of word N?+?2 influenced its viewing duration even when word N?+?1 was fixated prior to word N?+?2 viewing. These results provide compelling evidence for the view that the linguistic processing can encompass more than one word at a time.     

The target effect: Visual memory for unnamed search targets

Search targets are typically remembered much better than other objects even when they are viewed for less time. However, targets have two advantages that other objects in search displays do not have: They are identified categorically before the search, and finding them represents the goal of the search task. The current research investigated the contributions of both of these types of information to the long-term visual memory representations of search targets. Participants completed either a predefined search or a unique-object search in which targets were not defined with specific categorical labels before searching. Subsequent memory results indicated that search target memory was better than distractor memory even following ambiguously defined searches and when the distractors were viewed significantly longer. Superior target memory appears to result from a qualitatively different representation from those of distractor objects, indicating that decision processes influence visual memory.     

Dual representation of item positions in verbal short-term memory: Evidence for two access modes

Memory sets of N=1 ~ 5 digits were exposed sequentially from left-to-right across the screen, followed by N recognition probes. Probes had to be compared to memory list items on identity only (Sternberg task) or conditional on list position. Positions were probed randomly or in left-to-right order. Search functions related probe response times to set size. Random probing led to ramped, “Sternbergian” functions whose intercepts were elevated by the location requirement. Sequential probing led to flat search functions—fast responses unaffected by set size. These results suggested that items in STM could be accessed either by a slow search-on-identity followed by recovery of an associated location tag, or in a single step by following item-to-item links in study order. It is argued that this dual coding of location information occurs spontaneously at study, and that either code can be utilised at retrieval depending on test demands.     

Diversity during training enhances detection of novel stimuli

This research demonstrates that when individuals are expected to detect novel targets, they will be best prepared when trained with diverse categories. Participants were trained in a simulated luggage screening task in one of three conditions of diversity: high (participants searched for dangerous objects belonging to five different categories); low (participants searched for targets belonging to one of the five categories); and no training (control condition). After training, all participants were asked to look for the same novel dangerous objects in the bags. Results show that, during training, the low diversity condition resulted in highest hit rates and fastest response times. In contrast, after training, results were reversed: participants that trained in a high diversity condition were most effective at detecting novel targets. Those with no training at all were equally poor at detecting novel targets as those that trained in a low diversity condition.     

Animal foraging and the evolution of goal-directed cognition

Foraging- and feeding-related behaviors across eumetazoans share similar molecular mechanisms, suggesting the early evolution of an optimal foraging behavior called area-restricted search (ARS), involving mechanisms of dopamine and glutamate in the modulation of behavioral focus. Similar mechanisms in the vertebrate basal ganglia control motor behavior and cognition and reveal an evolutionary progression toward increasing internal connections between prefrontal cortex and striatum in moving from amphibian to primate. The basal ganglia in higher vertebrates show the ability to transfer dopaminergic activity from unconditioned stimuli to conditioned stimuli. The evolutionary role of dopamine in the modulation of goal-directed behavior and cognition is further supported by pathologies of human goal-directed cognition, which have motor and cognitive dysfunction and organize themselves, with respect to dopaminergic activity, along the gradient described by ARS, from perseverative to unfocused. The evidence strongly supports the evolution of goal-directed cognition out of mechanisms initially in control of spatial foraging but, through increasing cortical connections, eventually used to forage for information.