眼睛区域构型信息与特征信息的跨维共变增益效应及其加工特异性

面孔知觉可能在区域尺度上发生多维信息整合, 但迄今无特异性实验证据。本研究在两个实验中操纵面孔眼睛区域或嘴巴区域的单维构型或特征信息, 测量人们觉察单维变化或跨维共变的敏感度, 以此检测面孔区域尺度上的多维信息整合有何现象与规律, 进而揭示面孔知觉的多维信息整合机制。实验获得3个发现：(1)正立面孔眼睛区域的信息变化觉察呈现出“跨维共变增益效应”, 跨维信息共变觉察的敏感度显著高于任意一种单维信息变化觉察的敏感度; (2)“跨维共变增益效应”只在正立面孔的眼睛区域出现, 在倒置面孔的眼睛区域、正立面孔的嘴巴区域或倒置面孔的嘴巴区域都没有出现, 因此具有面孔区域特异性和面孔朝向特异性; (3)就单维信息变化觉察而言, 眼睛区域的敏感度不会受到面孔倒置的损伤, 但是嘴巴区域的敏感度会受到面孔倒置的显著损伤。综合可知, 面孔知觉确实会发生区域尺度上的信息整合, 它不是普遍性的信息量效应, 而是特异性的眼睛效应(只发生在正立面孔的眼睛区域)。这是面孔整体加工(face holistic processing)在单维信息分辨和多维信息整合之间建立联系的必经环节。这提示我们对全脸多维信息知觉整合的理解需要从传统的面孔整体加工假设升级到以眼睛为中心的层级化多维信息整合算法(a hierarchical algorithm for multi-dimensional information integration)。     

Extending affective capabilities for medical assistive robots

In this work, we discuss methodologies and implementation choices to enable a humanoid robot to estimate patients’ mood and emotions during postoperative home rehabilitation. The approach is modular and it has been implemented into a SoftBank Pepper robotic architecture; however, the approach is general and it can be easily adapted to other robotic platforms. A sample of an interactive session for the detection of the patient’s affective state is also reported.     

Fast face detection using a unified architecture for unconstrained and infrared face images

Human face detection along with its localization is a difficult task when the face is presented in the cluttered scene in an unconstrained scenario that might be with arbitrary pose variations, occlusions, random backgrounds and infrared (IR) environment. This paper proposes a novel face detection method which can address some of these issues and challenges quite successfully during face detection in unconstrained as well as infrared environments. It makes use of Fast Successive Mean Quantization Transform (FastSMQT) features for image enhancement and feature representation to deal with illumination and sensor insensitiveness. A split up Sparse Network of Winnows (SNoW) with Winnow updating rule is then exploited to speed up the original SNoW classifier. Finally, the features and classifiers are combined together with skin detection algorithm for face detection in crowd image and head orientation correction of near infrared faces. The proposed face detector is robust in handling pose, occlusion, illumination, blur and low image resolution. The experiment is performed on six challenging and publicly available databases, viz. BIOID, LFW, FDDB, UFI, WIDER FACE and IIT Delhi near infrared. The experimental results depict that the proposed method outperforms traditional as well as some advanced methods in detecting unconstrained and infrared faces under challenging situations.     

Demand characteristics and research into drug use

Abstract

Health research makes frequent use of verbal reports; and such reports are usually assumed to be the surface indicants of measurable entities such as attitudes, beliefs, intentions, etc. which reside inside the person. It is our assertion that verbal reports themselves are motivated and variable; they are functional and context-dependent and their meaning and significance are localised. Consequently discourse cannot be treated as if it were fixed and categorical data to be retrieved from memory by asking questions that appear objective or disinterested. A method is postulated, using a social perception analogy with signal detection (SD) theory. The method allows for the assessment of subject criterion, and permits an examination of signal-strength in terms of the researcher's motivation. Data are evaluated in terms of their “robustness”, a measure which derives from the variability of response in different contexts, and under different elicitation procedures. The method requires few assumptions to be made about the “truth” or “falsity” of verbal reports. It focuses on the types of social activities that are performed by utterances and thus on the contextual variability revealed by asking questions in different situations and in different ways. This procedure does not presume a direct correspondence between verbal reports and mental representations.     

Change detection inflates confidence on a subsequent recognition task

A face viewed under good encoding conditions is more likely to be remembered than a face viewed under poor encoding conditions. In four experiments we investigated how encoding conditions affected confidence in recognising faces from line-ups. Participants performed a change detection task followed by a recognition task and then rated how confident they were in their recognition accuracy. In the first two experiments the same faces were repeated across trials. In the final two experiments novel faces were used on each trial. Target-present and target-absent line-ups were utilised. In each experiment participants had greater recognition confidence after change detection than after change blindness. The finding that change detection inflates confidence, even for inaccurate recognitions, indicates recognition certainty can be a product of perceived encoding conditions rather than authentic memory strength.     

The role of athletes' pain-related anxiety in pain-related attentional processes

Numerous researchers have highlighted the social determinants of athletes' attitude toward pain, yet little is known about the role of cognitive processes and emotions that are related to pain in sport endeavors. There is evidence, in a dot probe paradigm, that individuals with chronic pain selectively orient their attention toward pain-related stimuli, but no studies have differentiated between the two attentional processes of hypervigilance that are evident in athletes: facilitated detection of threat and difficulty in disengaging attention from threatening stimuli. In the present study using a dot probe paradigm, we examined whether professional rugby players (N=58) with high pain-related anxiety (HPA) would show an attentional bias for pain-related threat, and whether this hypervigilance would reflect difficulty disengaging from threat or facilitated detection of threat. Rugby players with HPA oriented their attention toward pain-related threat with a concomitant difficulty disengaging from threat. Difficulty disengaging from painful stimuli may increase anxiety, and thus be maladaptive in sport. This is the first study to identify pain-related anxiety as a vulnerability marker in athletes' attentional biases.     

Using real-world scenes as contextual cues for search

Research on contextual cueing has demonstrated that with simple arrays of letters and shapes, search for a target increases in efficiency as associations between a search target and its surrounding visual context are learned. We investigated whether the visual context afforded by repeated exposure to real-world scenes can also guide attention when the relationship between the scene and a target position is arbitrary. Observers searched for and identified a target letter embedded in photographs of real-world scenes. Although search time within novel scenes was consistent across trials, search time within repeated scenes decreased across repetitions. Unlike previous demonstrations of contextual cueing, however, memory for scene-target covariation was explicit. In subsequent memory tests, observers recognized repeated contexts more often than those that were presented once and displayed superior recall of target position within the repeated scenes. In addition, repetition of inverted scenes, which made the scene more difficult to identify, produced a markedly reduced rate of learning, suggesting semantic information concerning object and scene identity are used to guide attention.     

Correspondence problems cause repositioning costs in visual working memory

Visual working memory performance often declines when objects are tested in new positions from those they were observed. We report an asymmetry in repositioning costs for orientation compared to colour memory (Experiment 1). Follow-up experiments demonstrated a similar asymmetry for line length memory compared to shape memory (Experiment 2). When different shades of the same colour category were used, however, repositioning costs emerged for colour as well (Experiment 3). Finally, a direct comparison experiment demonstrated an asymmetry for orientation compared to categorical colours, but in a task with no explicit memory demands (Experiment 4). These results challenge previous accounts of repositioning costs, suggesting that they emerge not due to the contents of visual working memory, but naturally because of correspondence procedures that must be executed in order to use a memory to judge the present.     

Prevalence-based decisions undermine visual search

In visual search, observers make decisions about the presence or absence of a target based on their perception of a target during search. The present study investigated whether decisions can be based on observers’ expectation rather than perception of a target. In Experiment 1, participants were allowed to make target-present responses by clicking on the target or, if the target was not perceived, a target-present button. Participants used the target-present button option more frequently in difficult search trials and when target prevalence was high. Experiment 2 and 3 employed a difficult search task that encouraged the use of prevalence-based decisions. Target presence was reported faster when target prevalence was high, indicating that decisions were, in part, cognitive, and not strictly perceptual. A similar pattern of responses were made even when no targets appeared in the search (Experiment 3). The implication of these prevalence-based decisions for visual search models is discussed.     

Dual-target search for high and low prevalence X-ray threat targets

Recent studies have shown that the prevalence of target presentation in visual search has an impact on target detection rates, and also that searching for two targets leads to a decrement in performance (the “dual-target cost”). In the present experiments, we added to previous work that has examined the interaction between the prevalence effect and dual-target cost, and also to previous work that has examined a full range of prevalence levels. We found no interaction between the dual-target cost and prevalence effect, though the response criterion in dual-target search did interact with target prevalence in an unexpected manner. Furthermore, we detected anasymmetry in the prevalence effect: It was more marked for high than low prevalence. Implications for real-world tasks are discussed.