Hearing speech against spatially separate competing speech versus competing noise

Listeners had the task of following a target speech signal heard against two competitors either located at the same spatial position as the target or displaced symmetrically to locations flanking it. When speech was the competitor, there was a significantly higher separation effect (maintained intelligibility with reduced target sound level), as compared with either steady-state or fluctuating noises. Increasing the extent of spatial separation slightly increased the effect, and a substantial contribution of interaural time differences was observed. When same- and opposite-sex voices were used, a hypothesis that the similarity between target and competing speech would explain the role for spatial separation was partly supported. High- and low-pass filtering showed that both parts of an acoustically similar competing signal contribute to the phenomenon. We conclude that, in parsing the auditory array, attention to spatial cues is heightened when the components of the array are confusable on other acoustic grounds.     

线索靶子关联和搜索策略对注意捕获的作用

采用线索化范式, 通过实验任务设计线索与靶子不同的关联并鼓励被试采用不同的搜索策略, 探讨线索与靶子间的知觉关联、语义关联及特征独子检测模式、特征搜索模式对注意捕获的作用。通过线索无效条件和线索有效条件反应时之差判断每一条件下的捕获量, 并综合各条件的反应情况做出结论如下：(1)线索与靶子的知觉关联调控注意捕获, 其效应不受语义关联和搜索策略影响; (2)线索与靶子的语义关联只在排除知觉关联后调控注意捕获; (3)控制知觉关联和语义关联后, 特征搜索模式不影响注意捕获, 而特征独子检测模式对注意捕获有影响。这表明语义知识和知觉经验根据当前任务要求共同作用指导个体的视觉加工, 表现了人类加工系统的灵活性和可调节性。     

Visual search at different spatial scales

Treisman and Gelade's (1980) feature-integration model claims that the search for separate ("primitive") stimulus features is parallel, but that the conjunctions of those features require serial scan. Recently, evidence has accumulated that parallel processing is not limited to these "primitive" stimulus features, but that combinations of features can also produce parallel search. In the experiments reported here, the processing of feature conjunctions was studied when the stimulus features of a combination were at different spatial scales. The patterns in the search array were composed of three cross-shaped or T-shaped (local) elements, which formed an oblique bar (the global pattern) 45 deg or 135 deg in orientation. When the target and distractors differed from each other at one spatial scale only (either in the bar orientation or in the shape of the local elements), target detection was independent of the number of distractors, i.e., the search was parallel. In the conjunction task, in which the target and distractors were defined as the combinations of the bar orientation and the element shape, i.e., both spatial scales were relevant, the detection of the target required slow serial scrutiny of the search array. It is possible that the conjunction search could not be performed in parallel because switches between the two scales (or spatial frequency channels) are linked to attention and the task required the use of both scales in order to find the target.     

Effect of spatial position on visual search for 3-D objects

We examined whether the position of objects in external space affects the visual-search task associated with the tilt of 3-D objects. An array of cube-like objects was stereoscopically displayed at a distance of 4.5 m on a large screen 1.5 m above or below eye height. Subjects were required to detect a downward-tilted target among upward-tilted distractors or an upward-tilted target among downward-tilted distractors. When the stimuli consisted of shaded parallelepipeds whose upper/bottom faces were lighter than their side faces, the upward-tilted target was detected faster. This result was in accordance with the 'top-view assumption' reported in previous research. Displaying stimuli in the upper position degraded overall performance. However, when the shaded objects whose upper/bottom faces were darker than their side faces were displayed, the detection of a downward-tilted target became as efficient as that of an upward-tilted target only at the upper position. These results indicate that it is possible for the spatial position of the stimulus to promote the detection of a downward-tilted target when shading and perspective information are consistent with the viewing direction.     

The effects of transient attention on spatial resolution and the size of the attentional cue

It has been shown that transient attention enhances spatial resolution, but is the effect of transient attention on spatial resolution modulated by the size of the attentional cue? Would a gradual increase in the size of the cue lead to a gradual decrement in spatial resolution? To test these hypotheses, we used a texture segmentation task in which performance depends on spatial resolution, and systematically manipulated the size of the attentional cue: A bar of different lengths (Experiment 1) or a frame of different sizes (Experiments 2-3) indicated the target region in a texture segmentation display. Observers indicated whether a target patch region (oriented line elements in a background of an orthogonal orientation), appearing at a range of eccentricities, was present in the first or the second interval. We replicated the attentional enhancement of spatial resolution found with small cues; attention improved performance at peripheral locations but impaired performance at central locations. However, there was no evidence of gradual resolution decrement with large cues. Transient attention enhanced spatial resolution at the attended location when it was attracted to that location by a small cue but did not affect resolution when it was attracted by a large cue. These results indicate that transient attention cannot adapt its operation on spatial resolution on the basis of the size of the attentional cue.     

Visual Search for a Tilted Target: Tests of Spatial Uncertainty Models

We report that spatial cueing of a parafoveal target in the presence of distractors enhances orientational acuity for that target. When no distractors were present, orientation thresholds were in the range 1-4 . For long exposure times, distractors increased threshold by the amount predicted from a winner-takes-all spatial uncertainty model. For short (100-msec) exposures followed by a random dot mask, the rise in threshold with distractors was considerably greater than that predicted from spatial uncertainty. For brief exposures the effect of distractors was greater when the target and distractors were spatially crowded rather than widely spaced. Adding a tilt to the distractors in the opposite direction to the target increased thresholds still further. Cueing the target with a spatial pointer decreased the effect of distractors, even when they were crowded. We suggest that when attention cannot be appropriately focused, discrimination is carried out by a relatively coarse texture analyser, which averages over several elements, and that focused attention permits the analysis of the target over a smaller area of space.     

文字线索浏览方向、空间位置与移动光标对伪忽视的影响

采用线段平分任务,以无文字线索作为基线条件,考察文字线索的浏览方向、空间位置和移动光标对具有两种不同方向阅读经验的熟练双语者伪忽视的影响。结果发现,无文字线索条件下,光标从左往右方向移动时被试的判断偏向于线段中点的右侧,而从右往左移动时,偏向于线段中点的左侧。在有文字线索条件下发现,文字线索的浏览方向和空间位置的交互作用显著,简单效应检验显示文字线索的浏览方向和空间位置一致时伪忽视明显,不一致时伪忽视消失。结果表明,文字线索浏览方向、空间位置与移动光标能够影响伪忽视。伪忽视的存在和消失,不仅与眼球运动有关,还有与大脑两半球的激活水平有关。研究结果支持了视觉扫描假设和激活朝向假设。     

视觉工作记忆回溯线索效应的产生机制：认知阶段分离

以往研究关于视觉工作记忆回溯线索效应的产生机制主要存在5种假设, 目前依然存在争议。本研究通过改进前人研究实验范式, 采用包含内源性回溯线索的颜色回忆报告范式, 进一步对这5种假设进行检验。在实验1中, 我们调控了线索与探测阵列之间的时间间隔, 发现不同时间间隔不影响无线索条件的行为表现, 而在正常线索条件中被试的记忆精度以及能记住的项目数量均优于无线索条件; 在实验2中, 我们对回溯线索伴随的干扰刺激类型进行控制, 结果显示, 在不同条件下记忆精度不存在差别, 但当回溯线索伴随干扰刺激呈现时, 被试能记住的项目数量会被降低, 降低程度受干扰刺激的类型调制; 在实验3中, 我们对伴随回溯线索的干扰刺激的呈现时间进行控制, 发现虽然回溯线索效应仍然存在, 但干扰刺激的呈现时间不会影响效应程度。研究结果表明, 回溯线索的出现使得被试能够在决策加工前完成内部注意资源的再分配, 从而避免了同时进行这两种认知加工与记忆表征维持本身竞争认知资源。本研究为认知阶段分离假设提供了支持证据, 对解决回溯线索效应产生机制的争议以及理解内部注意与视觉工作记忆的关系有重要意义。     

Visual search: spatial frequency and orientation

Observers searched for a Gaussian-windowed patch of sinewave grating (Gabor pattern) through displays containing varying numbers of other such patterns (distractors). When the spatial frequencies of target and distractors differed by +/- 2 octaves and their orientations by +/- 60 degrees, the search proceeded spatially in parallel irrespective of whether the target could be discriminated in terms of spatial frequency differences alone, orientation differences alone, or their combination. However, when target and distractors differed by only +/- .5 octave in spatial frequency and by +/- 15 degrees in orientation, the search was serial and self-terminating, again irrespective of the nature of the target-distractor differences. These findings show that, contrary to some suggestions, the preattentive detection of targets defined by conjunctions of spatial frequency and orientation may occur, but only when the spectral distance between target and distractors allows their encoding by independent mechanisms.     

Visual search asymmetry in pigeons

Pigeons received an odd-item search task that involved an array of 12 patterns containing 11 similar distractors and a single target. Pecks to the target resulted in the delivery of food. Accuracy was greater on trials when a distinctive feature was located in the target but not in the distractors, rather than when the feature was in the distractors but not in the target. This search asymmetry was influenced by the similarity of the target to the distractors. The results are similar to those obtained with humans.     

Limits of focused attention in three-dimensional space

The present experiment examined the shape of the attentional gradient in three-dimensional space. Subjects performed a response-compatibility task in which they were instructed to respond to a centrally located target and ignore flanking distractors. The irrelevant distractors were presented at combinations of seven different depths, three different horizontal separations, and three different vertical separations relative to the target. Depth was varied in a stereoscopic display viewed through polarized glasses. Overall, the size of the response-compatibility effect decreased with increased separation in all three dimensions. Interestingly, the response-compatibility effect was larger for horizontal separations than for vertical separations and was larger for crossed disparities than for uncrossed disparities. The results suggest an elliptical focus of attention, with steeper gradients in the vertical dimensions than in the horizontal dimensions. In addition, the results suggest, along the vertical dimension, a steeper gradient for objects located beyond the focus of attention relative to that for objects located between the observer and the focus of attention.     

Spatial constraints on visual-tactile cross-modal distractor congruency effects

Across three experiments, participants made speeded elevation discrimination responses to vibrotactile targets presented to the thumb (held in a lower position) or the index finger (upper position) of either hand, while simultaneously trying to ignore visual distractors presented independently from either the same or a different elevation. Performance on the vibrotactile elevation discrimination task was slower and less accurate when the visual distractor was incongruent with the elevation of the vibrotactile target (e.g., a lower light during the presentation of an upper vibrotactile target to the index finger) than when they were congruent, showing that people cannot completely ignore vision when selectively attending to vibrotactile information. We investigated the attentional, temporal, and spatial modulation of these cross-modal congruency effects by manipulating the direction of endogenous tactile spatial attention, the stimulus onset asynchrony between target and distractor, and the spatial separation between the vibrotactile target, any visual distractors, and the participant’s two hands within and across hemifields. Our results provide new insights into the spatiotemporal modulation of crossmodal congruency effects and highlight the utility of this paradigm for investigating the contributions of visual, tactile, and proprioceptive inputs to the multisensory representation of peripersonal space.     

早期ERP效应与视觉注意空间等级的脑调节机制

通过事件相关电位(ERP)记录研究注意的空间等级的脑内时程动态变化。视觉搜索任务的目标受不同大小提示范围的启动。提示范围增大时,识别目标的反应时延长,P1波幅增大而N1波幅减小,该效应在短间隔条件下尤为明显。P1增大反映了促进目标识别时,适当注意范围的空间等级变化需要额外的运算资源。而N1波幅减小则可能扩散了空间注意倾斜。研究结果提供了以下电生理学证据：注意空间等级的改变调节了早期视皮层的神经活动,并激活了视觉搜索中至少2个时间重叠的ERP成分。     

奖赏预期调节局部注意干扰效应

局部注意干扰效应(Localized attentional interference, LAI)是指在视觉搜索任务中同时搜索在空间上分离的两个目标时, 或者目标周围存在一个无关奇异项时, 这两个关键刺激相距较近时产生的干扰现象。本实验采用视觉搜索范式, 探讨了奖赏预期对局部注意干扰效应的影响。实验1采用双目标搜索任务, 要求被试判断搜索画面中两个奇异项刺激的形状是否相同。结果显示奖赏条件和无奖赏条件都表现出显著的距离主效应, 随着目标间距离增大, 被试的正确率提高, 反应时下降。同时, 在远距离时, 奖赏条件下的正确率高于无奖赏条件, 而在近距离时, 奖赏条件下的正确率反而低于无奖赏条件, 即, 奖赏条件下局部注意干扰效应反而增大。高动机状态增强了两个目标的表征, 反而不利于解决局部注意干扰效应。实验2采用单目标搜索任务, 要求被试判断特定目标的方位并忽略另一无关奇异项刺激。与实验1不同的是, 实验2仅在无奖赏条件下观察到显著的距离主效应, 即被试行为表现在远距离时更好; 而在奖赏条件下, 被试在近距离和远距离的表现一样好, 即没有局部注意干扰效应。这说明在奖赏预期条件, 个体可以有效抑制分心物刺激的干扰, 将注意集中于目标刺激的加工, 从而对局部注意干扰效应产生调节。整个研究表明, 奖赏整体上能够提高对任务相关刺激的表征, 并抑制任务无关刺激, 虽然这并不总是能够提高任务表现。     

IDENTITIES IN HARMONY: GENDER–WORK IDENTITY INTEGRATION MODERATES FRAME SWITCHING IN COGNITIVE PROCESSING

Professional women's identity integration—the perceived compatibility between work and gender identities—plays a role in how task or relationship information is processed. Seventy female business school students were primed with either their professional or their gender identity. Business women with higher identity integration showed an assimilation effect to the primed cue. Specifically, they showed higher task orientation than relationship orientation in a recognition task when primed with their professional identity, but less so when primed with their gender identity. Business women with lower identity integration showed a contrast effect to the primed cue: Their recognition reflected a task-relationship orientation opposite to the primed cue. We discuss the implications of these findings for understanding women's performance at work.     

Detecting distortions of peripherally presented letter stimuli under crowded conditions

When visual features in the periphery are close together they become difficult to recognize: something is present but it is unclear what. This is called “crowding”. Here we investigated sensitivity to features in highly familiar shapes (letters) by applying spatial distortions. In Experiment 1, observers detected which of four peripherally presented (8 deg of retinal eccentricity) target letters was distorted (spatial 4AFC). The letters were presented either isolated or surrounded by four undistorted flanking letters, and distorted with one of two types of distortion at a range of distortion frequencies and amplitudes. The bandpass noise distortion (“BPN”) technique causes spatial distortions in Cartesian space, whereas radial frequency distortion (“RF”) causes shifts in polar coordinates. Detecting distortions in target letters was more difficult in the presence of flanking letters, consistent with the effect of crowding. The BPN distortion type showed evidence of tuning, with sensitivity to distortions peaking at approximately 6.5 c/deg for unflanked letters. The presence of flanking letters causes this peak to rise to approximately 8.5 c/deg. In contrast to the tuning observed for BPN distortions, RF distortion sensitivity increased as the radial frequency of distortion increased. In a series of follow-up experiments, we found that sensitivity to distortions is reduced when flanking letters were also distorted, that this held when observers were required to report which target letter was undistorted, and that this held when flanker distortions were always detectable. The perception of geometric distortions in letter stimuli is impaired by visual crowding.     

The effect of exogenous spatial attention on auditory information processing

This study investigated the effect of exogenous spatial attention on auditory information processing. In Experiments 1, 2 and 3, temporal order judgment tasks were performed to examine the effect. In Experiment 1 and 2, a cue tone was presented to either the left or right ear, followed by sequential presentation of two target tones. The subjects judged the order of presentation of the target tones. The results showed that subjects heard both tones simultaneously when the target tone, which was presented on the same side as the cue tone, was presented after the target tone on the opposite side. This indicates that spatial exogenous attention was aroused by the cue tone, and facilitated subsequent auditory information processing. Experiment 3 examined whether both cue position and frequency influence the resulting information processing. The same effect of spatial attention was observed, but the effect of attention to a certain frequency was only partially observed. In Experiment 4, a tone fusion judgment task was performed to examine whether the effect of spatial attention occurred in the initial stages of hearing. The result suggests that the effect occurred in the later stages of hearing.     

FLEXIBILITY IN SPATIAL ATTENTION BEFORE AND AFTER PRACTICE

Abstract— These experiments used spatial probes to measure how spatial attention is allocated across the visual field during search for a target letter in an eight-letter array. There were three main findings. Attentional strength is flexibly adjusted according to the confusability between target and distractors. Distractor locations near the target receive more inhibition than those farther from the target, indicating that the nearby distractors interfere more with target identification. Despite the fact that consistent practice improves search rate it does not diminish the strength of spatial attention in this task.     

The interaction of objective and subjective organizations in a localization search task

We investigated how both objective and subjective organizations affect perceptual organization and how this perceptual organization, in turn, influences observers’ performance in a localization search task. Two groups of observers viewing exactly the same stimuli (objective organization) performed in significantly different ways, depending on how they were induced to parse the display (subjective organization). In Experiments 1 and 2, the observers were asked to describe the location of a tilted target among a varying number of vertical or horizontal distractors. Subjective organization was induced by instructing observers to parse the display into either three horizontal regions (rows) or three vertical regions (columns). The position of the target was critical: location performance, as assessed by reaction time and errors, was consistently impaired at the locations adjacent to the boundaries defining the regions, producing what we refer to as thesubjective boundary effect. Furthermore, the extent of this effect depended on whether the stimulus-driven and conceptually driven information concurred or conflicted. This made location information more or less accessible. In Experiment 1, the strength of objective grouping was a function of the proximity of the items (near or far conditions) and their orientation in a 6×6 matrix. In Experiment 2, the strength of objective grouping was a function of similarity of color (items were color coded by rows or by columns) and the orientation of the items in a 9×9 matrix. The subjective boundary effect was more pronounced when the display promoted grouping in the direction orthogonal to that of the task (e.g., when observers parsed by rows but vertical distractors were closer together [Experiment 1] or color coded [Experiment 2] to induce global columns). In contrast, this effect decreased when the direction of both objective and subjective organizations was parallel (e.g., when observers parsed by rows and horizontal distractors were closer together [Experiment 1] or were color coded [Experiment 2] to induce global rows). A localization search task proved to be an ideal forum in which objective and subjective organizations interacted. We discuss how these results indicated that observers’ performance in a localization task was determined by the interaction of objective and subjective organizations, and that the resulting perceptual organization constrained coarse location information.     

Personally-significant information affects performance only within the focus of attention: a direct manipulation of attention

It has been suggested that personally significant (PS) information interferes with performance only when presented within the focus of attention. However, this claim was never tested by a systematic manipulation of attention, but only by using correlative measures of its locus. We addressed this issue in two experiments, utilizing a cued visual search paradigm that allowed us to directly manipulate attention and to measure behavioral and physiological responses. One of the stimuli in the search display had a higher luminance value (i.e., was cued), and, orthogonally, one of the stimuli could be a PS or neutral name. When the cue did not predict target location, PS distractors mildly interfered with task performance, regardless of the cue's location. However, when the cue predicted target location, responses were facilitated for cued targets, indicating that attention was shifted to the cue. Importantly, PS distractors interfered with task performance and elicited enhanced orienting responses only when they were cued. This implies that PS information affects performance only when presented within but not outside the focus of attention.