Paradoxical cross-over due to attention to high or low spatial frequencies

The mechanisms underlying the right hemisphere's dominance for spatial and attentional functions lacks a comprehensively explanation. For example, perceptual biases, as observed in line bisection and related tasks, might be caused by an attentional asymmetry or by perceptual processes such as a specialization of the left and right hemisphere for high and low spatial frequencies (SFs), respectively. Here we used the gratingscales task to measure perceptual bias in SF judgements, and we cued participants' attention either to high or low SFs. Participants showed a leftward bias when comparing the high SF components of the stimulus, and a rightward bias when comparing the low SF components-opposite to what would be expected from a hemispheric lateralization for SFs. Two control experiments used different strategies to manipulate the width of the attentional window. However, we observed no influence on perceptual bias, thus ruling out the possibility that the results in Experiment 1 were due to differences in attentional window size. These data support the idea of an attentional asymmetry underlying perceptual bias. Our results provide novel support for the role of attentional asymmetry in perceptual biases.     

Spatial frequency filtering and the direct control of fixation durations during scene viewing

The present study employed a saccade-contingent change paradigm to investigate the effect of spatial frequency filtering on fixation durations during scene viewing. Subjects viewed grayscale scenes while encoding them for a later memory test. During randomly chosen saccades, the scene was replaced with an alternate version that remained throughout the critical fixation that followed. In Experiment 1, during the critical fixation, the scene could be changed to high-pass and low-pass spatial frequency filtered versions. Under both conditions, fixation durations increased, and the low-pass condition produced a greater effect than the high-pass condition. In subsequent experiments, we manipulated the familiarity of scene information during the critical fixation by flipping the filtered scenes upside down or horizontally. Under these conditions, we observed lengthening of fixation durations but no difference between the high-pass and low-pass conditions, suggesting that the filtering effect is related to the mismatch between information extracted within the critical fixation and the ongoing scene representation in memory. We also conducted control experiments that tested the effect of changes to scene orientation (Experiment 2a) and the addition of color to a grayscale scene (Experiment 2b). Fixation distribution analysis suggested two effects on the distribution fixation durations: a fast-acting effect that was sensitive to all transsaccadic changes tested and a later effect in the tail of the distribution that was likely tied to the processing of scene information. These findings are discussed in the context of theories of oculomotor control during scene viewing.     

Categorical implicit learning in real-world scenes: evidence from contextual cueing

The present study examined the extent to which learning mechanisms are deployed on semantic-categorical regularities during a visual searching within real-world scenes. The contextual cueing paradigm was used with photographs of indoor scenes in which the semantic category did or did not predict the target position on the screen. No evidence of a facilitation effect was observed in the predictive condition compared to the nonpredictive condition when participants were merely instructed to search for a target T or L (Experiment 1). However, a rapid contextual cueing effect occurred when each display containing the search target was preceded by a preview of the scene on which participants had to make a decision regarding the scene's category (Experiment 2). A follow-up explicit memory task indicated that this benefit resulted from implicit learning. Similar implicit contextual cueing effects were also obtained when the scene to categorize was different from the subsequent search scene (Experiment 3) and when a mere preview of the search scene preceded the visual searching (Experiment 4). These results suggested that if enhancing the processing of the scene was required with the present material, such implicit semantic learning can nevertheless take place when the category is task irrelevant.     

场景知觉及其研究范式

场景知觉关注的是人如何知觉和加工复杂的真实环境信息。场景包括物体和背景两个重要的组成部分,根据复杂性与真实性程度,场景刺激材料可以分为三种不同的类型。已有研究主要从自上而下和自下而上两种方式来解释场景知觉中信息的提取和加工,也有研究试图从二者交互的角度来进行解释。此外,基于不同的实验目的和技术,研究者分别采用了眼动、背景提示、物体觉察、变化觉察和点线索追随几种不同的研究范式来探讨场景信息的知觉问题。场景知觉研究在场景的定义、不同范式间的整合、研究内部效度和不同加工阶段的加工方式四个方面还需要进一步深入和探讨     

How Are Different Properties of a Scene Encoded in Visual Memory?

Recent studies in scene perception suggest that much of what observers believe they see is not retained in visual memory. Depending on the roles they play in organizing the perception of a scene, different visual properties may require different amounts of attention to be incorporated into a mental representation of the scene. The goal of this study was to compare how three visual properties of scenes, colour, object position, and object presence, are encoded in visual memory. We used a variation on the change detection “flicker” task and measured the time to detect scene changes when: (1) a cue was provided regarding the type of change; and, (2) no cue was provided. We hypothesized that cueing would enhance the processing of visual properties that require more attention to be encoded into scene representations, whereas cueing would not have an effect for properties that are readily or automatically encoded in visual memory. In Experiment 1, we found that there was a cueing advantage for colour changes, but not for position or presence changes. In Experiment 2, we found the same cueing effect regardless of whether the colour change altered the configuration of the scene or not. These results are consistent with the idea that properties that typically help determine the configuration of the scene, for example, position and presence, are better encoded in scene representations than are surface properties such as colour.     

How does information from low and high spatial frequencies interact during scene categorization?

Current models of visual perception suggest that, during scene categorization, low spatial frequencies (LSF) are rapidly processed and activate plausible interpretations of visual input. This coarse analysis would be used to guide subsequent processing of high spatial frequencies (HSF). The present study aimed to further examine how information from LSF and HSF interact and influence each other during scene categorization. In a first experimental session, participants had to categorize LSF and HSF filtered scenes belonging to two different semantic categories (artificial vs. natural). In a second experimental session, we used hybrid scenes as stimuli made by combining LSF and HSF from two different scenes which were semantically similar or dissimilar. Half of the participants categorized LSF scenes in hybrids, and the other half categorized HSF scenes in hybrids. Stimuli were presented for 30 or 100?ms. Session 1 results showed better performance for LSF than HSF scene categorization. Session 2 scene categorization was faster when participants attended and categorized LSF than HSF scene in hybrids. The semantic interference of a semantically dissimilar HSF scene on LSF scene categorization was greater than the semantic interference of a semantically dissimilar LSF scene on HSF scene categorization, irrespective of exposure duration. These results suggest a LSF advantage for scene categorization, and highlight the prominent role of HSF information when there is uncertainty about the visual stimulus, in order to disentangle between alternative interpretations.     

靶刺激变换与情景信息属性对真实情景再认的影响

采用眼动研究范式,通过两个实验考察靶刺激变换与情景信息属性对情景再认的影响。实验一结果显示,靶刺激变换对情景再认、靶刺激所属兴趣区的凝视时间均有显著影响,这表明在情景再认过程中,观察者会有意识地搜索靶刺激,靶刺激具有诊断效应;实验二应用了知觉信息与语义信息重合和分离两种情景材料。结果显示,观察者对语义信息的首次注视次数显著多于知觉信息;观察者对知觉信息和语义信息分离条件下语义信息的首次注视时间显著长于重合条件下。这一结果提示,在情景识别过程中,语义信息具有注意优先性,但其优先性会受到知觉信息启动的干扰。     

Inhibition of return in subliminal letter priming

The present study combined exogenous spatial cueing with masked repetition priming to study attentional influences on the processing of subliminal stimuli. Participants performed an alphabetic decision task (letter versus pseudo-letter classification) with central targets and briefly presented peripherally located primes that were either cued or not cued by an abrupt onset. A relatively long delay between cue and prime was used to investigate the effect of inhibition of return (IOR) on the processing of subliminal masked primes. Primes presented to the left visual field showed standard effects of Cue Validity and no IOR (significant priming with valid cues only). Primes presented to the right visual field showed no priming from valid cues (an IOR effect), and priming with invalid cues that depended on hand of response to letter targets (right-hand in Experiment 1, left-hand in Experiment 2). The results are interpreted in terms of a differential speed of engagement and disengagement of attention to the right and left visual fields for alphabetic stimuli, coupled with a complex interaction that arises between Prime Relatedness and response-hand.     

Channel surfing in the visual brain

Vision provides us with an ever-changing neural representation of the world from which we must extract stable object categorizations. We argue that visual analysis involves a fundamental interaction between the observer's top-down categorization goals and the incoming stimulation. Specifically, we discuss the information available for categorization from an analysis of different spatial scales by a bank of flexible, interacting spatial-frequency (SF) channels. We contend that the activity of these channels is not determined simply bottom-up by the stimulus. Instead, we argue that, following perceptual learning a specification of the diagnostic, object-based, SF information dynamically influences the top-down processing of retina-based SF information by these channels. Our analysis of SF processing provides a case study that emphasizes the continuity between higher-level cognition and lower-level perception.     

Attentional coding of categorical relations in scene perception: evidence from the flicker paradigm

The purpose of the present investigation was to determine whether the positions of objects in a scene are coded relative to one another categorically (i.e., above, below, or side of; Experiment 1) and to determine whether spatial position in scene perception is coded preattentively or only under focused attention (Experiment 2). In Experiment 1, participants viewed alternating versions of a scene in which one of the objects in the scene changed its categorical relationship to the closest object in the scene, changed only its metric relationship to the closest object in a scene, or appeared and disappeared. Participants were faster at detecting changes that disrupted categorical relations than at detecting changes that disrupted only metric relations. In Experiment 2, this categorical advantage still occurred even when participants were cued to the location of the change. These results suggest that categorical spatial relations are being coded in scene perception and that attention is required in order to encode spatial relations.     

上下文预期在快速场景识别中的作用

本研究首先考察上下文预期是否能够影响快速场景识别,进而通过比较不同空间频率的场景信息来探究上下文预期在快速场景识别不同阶段的作用。共包括3个实验:实验1采用双眼竞争范式,考察对快速呈现场景刺激的主观选择是否受到上下文预期的影响;实验2采用词汇分类与快速场景识别的双任务范式,比较预期与非预期条件下快速场景识别绩效的差异;实验3分别以低频信息(实验3a)和高频信息(实验3b)作为实验材料,探讨预期效应的作用阶段。结果发现:上下文预期可以影响快速场景识别过程中的主观选择与反应绩效;对不同空间频率的场景信息,场景刺激与预期相一致时均可以提高辨别力,但预期对反应偏好的影响只发生在对高空间频率场景信息的加工阶段。因此,上下文预期在快速场景识别不同加工阶段的作用不同,快速场景识别需要结合不同空间频率信息加工的结果。     

The spider does not always win the fight for attention: Disengagement from threat is modulated by goal set

Stimulus-driven preferential attention to threat can be modulated by goal-driven attention. However, it remains unclear how this goal-driven modulation affects specific attentional components implied in threat interference. We hypothesise that goal-driven modulation most strongly impacts delayed disengagement from threat. A spatial cueing task was used that disentangles delayed disengagement from attentional capture by tightly manipulating the locus of attention at the time of target onset. Different top-down goals were induced by instructing participants to identify bird/fish targets (Experiment 1) or spider/cat targets (Experiment 2) among animal non-targets. Delayed disengagement from a non-target spider was observed only when the spider was part of the target set, not when it was task-irrelevant. This corroborates evidence that threat stimuli do not necessarily override goal-driven attentional control and that extended processing of threatening distractors is not obligatory.     

The effect of scene structure on time perception

The current experiments examined the hypothesis that scene structure affects time perception. In three experiments, participants judged the duration of realistic scenes that were presented in a normal or jumbled (i.e., incoherent) format. Experiment 1 demonstrated that the subjective duration of normal scenes was greater than subjective duration of jumbled scenes. In Experiment 2, gridlines were added to both normal and jumbled scenes to control for the number of line terminators, and scene structure had no effect. In Experiment 3, participants performed a secondary task that required paying attention to scene structure, and scene structure's effect on duration judgements reemerged. These findings are consistent with the idea that perceived duration can depend on visual–cognitive processing, which in turn depends on both the nature of the stimulus and the goals of the observer.     

Usage of spatial scales for the categorization of faces, objects, and scenes

The role of spatial scales (or spatial frequencies) in the processing of faces, objects, and scenes has recently seen a surge of research activity. In this review, we will critically examine two main theories of scale usage. The fixed theory proposes that spatial scales are used in a fixed, perceptually determined order (coarse to fine). The flexible theory suggests instead that usage of spatial scales is flexible, depending on the requirements of visual information for the categorization task at hand. The implications of the theories are examined for face, object, and scene categorization, attention, perception, and representation.     

空间工作记忆负载对真实场景情境提示效应的影响

重复的画面布局能够促进观察者对目标项的搜索 (情境提示效应)。本研究采用双任务范式,分别在视觉搜索任务的学习阶段 (实验2a) 和测验阶段 (实验2b) 加入空间工作记忆任务, 并与单任务基线 (实验1)进行比较, 考察空间工作记忆负载对真实场景搜索中情境线索学习和情境提示效应表达的影响。结果发现: 空间负载会增大学习阶段的情境提示效应量, 同时削弱测验阶段的情境提示效应量, 而不影响情境线索的外显提取。由此可见, 真实场景中情境线索的学习和提示效应的表达均会受到有限的工作记忆资源的影响, 但情境线索提取的外显性不变。     

The number line effect reflects top-down control

Recent evidence indicates that central directional stimuli, such as eyes and arrows, trigger rapid, reflexive shifts of spatial attention. A study by Fischer, Castel, Dodd, and Pratt (2003) suggested that a similar effect might also apply to central numbers, as if a digit's meaning causes attention to be oriented to its relative position on a left-to-right mental number line. However, unlike central eyes and arrows, the orienting effect for central digits emerges slowly, suggesting that top-down endogenous processes may be mediating this effect. Here, we report a series of three experiments that strongly support this hypothesis. Experiment 1 replicated Fischer et al.'s left-to-right number line effect. Experiment 2 showed that this effect could be completely reversed by merely asking participants to imagine a number line running from right to left. Experiment 3 showed that a left-to-right number line effect could be abolished by presenting targets above and below central fixation, as well as to the left and right of center. Experiment 3 also showed that other mental sets, such as imagining a clock, result in attention's being oriented in accordance with where the central digits are represented on a clock face. Together, these data indicate that the spatial representations and attentional orienting related to the perception of digits are both fragile and flexible and depend critically on the top-down spatial mental sets adopted by individuals.     

Selective attention,diffused attention,and the development of categorization

How do people learn categories and what changes with development? The current study attempts to address these questions by focusing on the role of attention in the development of categorization. In Experiment 1, participants (adults, 7-year-olds, and 4-year-olds) were trained with novel categories consisting of deterministic and probabilistic features, and their categorization and memory for features were tested. In Experiment 2, participants’ attention was directed to the deterministic feature, and in Experiment 3 it was directed to the probabilistic features. Attentional cueing affected categorization and memory in adults and 7-year-olds: these participants relied on the cued features in their categorization and exhibited better memory of cued than of non-cued features. In contrast, in 4-year-olds attentional cueing affected only categorization, but not memory: these participants exhibited equally good memory for both cued and non-cued features. Furthermore, across the experiments, 4-year-olds remembered non-cued features better than adults. These results coupled with computational simulations provide novel evidence (1) pointing to differences in category representation and mechanisms of categorization across development, (2) elucidating the role of attention in the development of categorization, and (3) suggesting an important distinction between representation and decision factors in categorization early in development. These issues are discussed with respect to theories of categorization and its development.     

The initial stage of visual selection is controlled by top-down task set: new ERP evidence

Salient visual singleton stimuli produce spatial cueing effects indicative of attentional capture only when they match current task sets, suggesting that capture is subject to top-down control. However, such task-set contingent capture effects could be associated with the top-down controlled disengagement of attention from non-matching stimuli that follows their initial bottom-up salience-driven selection. Using the N2pc component as an event-related potential marker of attentional capture, we demonstrate that top-down task set already controls the initial rapid selection of salient visual singleton stimuli prior to any subsequent attentional disengagement. These findings provide new evidence for the primacy of top-down control over bottom-up salience in attentional capture.     

The eye gaze direction of an observed person can bias perception,memory, and attention in adolescents with and without autism spectrum disorder

The reported experiments aimed to investigate whether a person and his or her gaze direction presented in the context of a naturalistic scene cause perception, memory, and attention to be biased in typically developing adolescents and high-functioning adolescents with autism spectrum disorder (ASD). A novel computerized image manipulation program presented a series of photographic scenes, each containing a person. The program enabled participants to laterally maneuver the scenes behind a static window, the borders of which partially occluded the scenes. The gaze direction of the person in the scenes spontaneously cued attention of both groups in the direction of gaze, affecting judgments of preference (Experiment 1a) and causing memory biases (Experiment 1b). Experiment 2 showed that the gaze direction of a person cues visual search accurately to the exact location of gaze in both groups. These findings suggest that biases in preference, memory, and attention are caused by another person’s gaze direction when viewed in a complex scene in adolescents with and without ASD