Anticipating intentional actions: The effect of eye gaze direction on the judgment of head rotation

Using a representational momentum paradigm, this study investigated the hypothesis that judgments of how far another agent’s head has rotated are influenced by the perceived gaze direction of the head. Participants observed a video-clip of a face rotating 60° towards them starting from the left or right profile view. The gaze direction of the face was either congruent with, ahead of, or lagging behind the angle of rotation. Following this, two static faces, at varying angles of rotation with respect to the end-point angle of the face in the video-clip, were presented simultaneously. The task of the participants was to decide which of the two heads was at an angle best resembling the angle of the end-point of the moving face. The critical test condition consisted of one test face oriented at 10° before, and the other at 10° after the end-point. The ‘lagging behind’ gaze condition elicited a significant underestimation of the rotation compared to the ‘congruent’ and ‘ahead’ gaze conditions. Participants did not exhibit similar biases when judging the rotation of several non-face control stimuli with visual features that mimicked different aspects of gaze direction. The findings suggest that when the gaze direction of a perceived agent is incongruent with the direction of the agent’s head motion observers automatically utilise this discrepancy to adjust their inferences about the agent’s intended heading direction.     

Visual versus phonological abilities in Spanish dyslexic boys and girls

Phonological and visual theories propose different primary deficits as part of the explanation for dyslexia. Both theories were put to test in a sample of Spanish dyslexic readers. Twenty-one dyslexic and 22 typically-developing children matched on chronological age were administered phonological discrimination and awareness tasks and coherent motion perception tasks. No differences were found between groups on the coherent motion tasks, whereas dyslexic readers were impaired relative to controls on phonological discrimination tasks. Gender differences followed the opposite pattern, with no differences on phonological tasks, and dyslexic girls performing significantly worse than dyslexic boys in coherent motion perception. These results point to the importance of phonological deficits related to speech perception in Spanish, and to possible gender differences in the neurobiological bases for dyslexia.     

孤独症谱系障碍者的生物运动探测障碍：基于行为与神经的证据

关于孤独症谱系障碍个体探测生物运动的能力是否受损,已有行为研究尚存分歧。导致分歧的原因可能是实验刺激、实验任务和测量指标存在差异。然而,神经研究却一致证实其潜在的神经机制存在异常。领域特殊性观点认为该障碍可能是基于后侧颞上沟功能异常的社会性功能障碍,也可能是基于镜像神经元功能异常的社会性功能障碍;而领域一般性观点认为该障碍可能是基于背侧视觉流功能异常的视运动知觉障碍,也可能基于脑功能联结异常的弱中央统合障碍。据此,本文将从研究范式、行为表现及潜在机制三个方面梳理相关研究,以期为后续研究提供新方向。     

客体的视觉工作记忆研究进展

近年来,客体信息的视觉工作记忆问题引发了大量研究,并获得不少成果。本文对视觉工作记忆的研究范式,客体在视觉工作记忆中的存储方式、容量及保持时间等相关研究进行了概述,重点介绍关于视觉工作记忆存储单元和容量问题的"强客体"假设、"弱客体"假设和双重存储机制假设,并提出进一步的研究思路。     

人眼深度运动知觉的研究

人类的深度运动知觉,是通过检测二维平面内的相对运动而形成的。本文在心理物理学实验基础上,揭示该机制的数学与生理学实现形式。视觉系统中存在对视平面内的相对运动敏感的神经元,构成深度运动的检测机制,产生单眼深度运动知觉与双眼深度运动知觉。在心理学上,视觉利用物体视角变化及大小知觉的恒常性判断深度运动。文中还初步讨论了人类的深度运动知觉与蜜蜂,家蝇等昆虫的深度运动知觉的区别。     

Random error in holistic evaluations and additive decompositions of multiattribute utility — an empirical comparison

This paper details the results of an empirical investigation of the random errors associated with decomposition estimates of multiattribute utility. In a riskless setting, two groups of subjects were asked to evaluate multiattribute alternatives both holistically and with the use of an additive decomposition. For one group, the alternatives were described in terms of three attributes, and for the other in terms of five. Estimates of random error associated with the various elicitations (holistic, single-attribute utility, scaling constants, or weights) were obtained using a test-retest format. It was found for both groups that the additive decomposition had significantly smaller levels of random error than the holistic evaluation. However, the number of attributes did not seem to make a significant difference to the amount of random error associated with the decomposition estimates. The levels of error found in the various elicitations were consistent with theoretical bounds that have recently been proposed in the literature. These results show that the structure imposed on the problem through decomposition results in measurable improvement in quality of the multiattribute utility judgements, and contribute to a greater understanding of the decomposition method in decision analysis.     

Summarization of videos by analyzing affective state of the user through crowdsource

Video summarization is one of the key techniques to access and manage a huge chunk of videos. Video summarization is used to extract the effective contents of a video sequence to generate a concise representation of its content. The involvement of crowdsourcing models in recent years is effectively used by researchers in E-commerce domain to increase the quality of the data contents. In this paper, we present a video summarization framework based on users emotion while they watch videos by analyzing cerebral activities through Electroencephalogram (EEG) signals. Three emotions, namely happy, sad and neutral have been extracted from the EEG signals. Video frames have been synchronized with EEG signals and tagged with various emotions. Finally, a crowdsourcing model has been used for effective summarization of the videos. The qualitative assessment of video summarization has been conducted with the help of user ratings using online Google Forms application. EEG signals of 28 users have been recorded while video streams of different emotions. An average accuracy of 83.93% has been recorded in emotion classification using crowdsourcing. Output summarized videos include dynamic video skims and the corresponding audio stream for better understanding.     

Revisiting the metacontrast dissociation: Comparing sensitivity across different measures and tasks

In the metacontrast dissociation procedure, presenting a masked shape prime prior to a visible shape target leads to reaction-time effects of the prime in an indirect measure, although participants cannot consciously detect prime shapes in a direct measure (Klotz & Neumann, 1999 Klotz, W. and Neumann, O. 1999. Motor activation without conscious discrimination in metacontrast masking. Journal of Experimental Psychology: Human Perception and Performance, 25: 976–992.  [Google Scholar]). This has been taken as evidence for the processing of unconscious input. The results of the present metacontrast dissociation study indicate that although participants are unable to consciously report the shape of the prime, they can consciously perceive motion between masked primes and visible targets in a hybrid direct/indirect measure (Experiments 1 and 3). This indicates that former tests did not provide an exhaustive measure for residual conscious perception of the prime in the metacontrast dissociation procedure. Further tests, however, reveal that residual motion perception cannot account for performance in the indirect measure (Experiments 2 and 3). Although the results thus leave the conception of processing of unconscious input intact, they may prompt a revision of its criteria.     

Dynamic action in virtual environments: Constraints on the accessibility of action knowledge in children and adults

In a series of three experiments, we probed the accessibility of action knowledge in different versions of a virtual environment (VE) with 7-year-old children and adults. Using a PHANToM^TM haptic interface, participants performed a virtual throwing task in which they tried to propel a ball from a table to hit a target on the ground. In Experiments 1 and 2, the virtual scene was presented on a computer monitor, and, in Experiment 3, it was projected by using a video projector so that the vertical and horizontal dimensions and the spatial location of the VE corresponded to the real-world dimensions. Results indicate that action knowledge is accessible even in a nonimmersive VE, but also suggest that the need to recalibrate perceptual-motor mappings constrains the accessibility of this kind of intuitive knowledge.     

Methodological and empirical developments for the Ratcliff diffusion model of response times and accuracy

Summerfield, Egner, Mangels, and Hirsch (2006) suggested that visual misperception may be triggered by strong yet wrong expectation when sensory data are insufficient. Bar (2003) posits that immediately after stimulus presentation, low frequency spatial information (LFSI) convey the global form of the image which is matched to stored representations in the orbitofrontal cortex to generate predictions of the input. We used signal detection to test whether a strong prediction induced by informative global form, hence reducing the number of possible input matches, would facilitate recognition, but at the price of increasing the rate of misperceptions. Twenty-five participants were presented with target and foil images that shared global form, but differed in details. Pictures with informative global form resulted in higher confidence in recognition and shorter reaction times, but increased false alarms. Predictions of sensory input based on low frequency spatial information allow quick, facilitated recognition. However, the price for speed is the increased rate of misperceptions.