Cognitive mechanisms of visuomotor transformation in movement imitation: Examining predictions based on models of apraxia and motor control

When we observe a movement and then reproduce it, how is this visual input transformed into motor output? Studies on stroke patients with apraxia suggest that there may be two distinct routes used for gesture imitation; an indirect route that recruits stored movement memories (motor programs) and a direct route that bypasses them. The present study examined 30 healthy adults ages 18–80 (mean age = 44.0 years, SD = 19.5) to learn how motor programs are recruited or bypassed in movement imitation depending upon task conditions (whether familiar letters or novel shapes are imitated) and perceptual factors (whether shapes or letters are perceived). Subjects were asked to imitate the movements of a model who formed shapes and letters on a sheer mesh screen, and to report whether they perceived the task as a shape or a letter. Movements were recorded using a Vicon motion analysis system, and subsequently analyzed to determine the degree of difference between the demonstrated and produced movements. As predicted, letter perception on the letter tasks resulted in increased temporal error when the demonstrated stroke order conflicted with subjects’ habitual pattern of letter formation. No such interference effects were observed when the letter tasks were perceived as shapes. These findings are discussed in the context of current theories on imitation, and implications for rehabilitation and motor re-learning are presented.     

Adapting to life’s slings and arrows: Individual differences in resilience when recovering from an anticipated threat

Following highly negative events, people are deemed resilient if they maintain psychological stability and experience fewer mental health problems. The current research investigated how trait resilience [Block, J., & Kremen, A. M. (1996). IQ and ego-resiliency: Conceptual and empirical connections and separateness. Journal of Personality and Social Psychology, 70(2), 349–361, ER89] influences recovery from anticipated threats. Participants viewed cues (‘aversive’, ‘threat’, ‘safety’) that signified the likelihood of an upcoming picture (100% aversive, 50/50 aversive/neutral, or 100% neutral; respectively), and provided continuous affective ratings during the cue, picture, and after picture offset (recovery period). Participants high in trait resilience (HighR) exhibited more complete affective recovery (compared to LowR) after viewing a neutral picture that could have been aversive. Although other personality traits previously associated with resilience (i.e., optimism, extraversion, neuroticism) predicted affective responses during various portions of the task, none mediated the influence of trait resilience on affective recovery.     

Human and machine perception of biological motion

More than 30 years ago, Johansson was the first to show that humans are capable of recovering information about the identity and activity of animate creatures rapidly and reliably from very sparse visual inputs – the phenomenon of biological motion. He filmed human actors in a dark setting with just a few strategic points on the body marked by lights – so-called moving light displays (MLDs). Subjects viewing the MLDs reported a vivid impression of moving human forms, and were even able to tell the activity in which the perceived humans were engaged. Subsequently, the phenomenon has been widely studied and many attempts have been made to model and to understand it. Typical questions that arise are: How precisely is the sparse low-level information integrated over space and time to produce the global percept, and how important is world knowledge (e.g., about animal form, locomotion, gravity, etc.)? In an attempt to answer such questions, we have implemented a machine-perception model of biological motion. If the computational model can replicate human data then it might offer clues as to how humans achieve the task. In particular, if it can do so with no or minimal world knowledge then this knowledge cannot be essential to the perception of biological motion. To provide human data for training and against which to assess the model, an extensive psychophysical experiment was undertaken in which 93 subjects were shown 12 categories of MLDs (e.g., normal, walking backwards, inverted, random dots, etc.) and were asked to indicate the presence or absence of natural human motion. Machine perception models were then trained on normal sequences as positive data and random sequences as negative data. Two models were used: a k-nearest neighbour (k-NN) classifier as an exemplar of ‘lazy’ learning and a back-propagation neural network as an exemplar of ‘eager’ learning. We find that the k-NN classifier is better able to model the human data but it still fails to represent aspects of knowledge about body shape (especially how relative joint positions change under rotation) that appear to be important to human judgements.     

The automaticity of perceiving animacy: Goal-directed motion in simple shapes influences visuomotor behavior even when task-irrelevant

Visual processing recovers not only simple features, such as color and shape, but also seemingly higher-level properties, such as animacy. Indeed, even abstract geometric shapes are readily perceived as intentional agents when they move in certain ways, and such percepts can dramatically influence behavior. In the wolfpack effect, for example, subjects maneuver a disc around a display in order to avoid several randomly moving darts. When the darts point toward the disc, subjects (falsely) perceive that the darts are chasing them, and this impairs several types of visuomotor performance. Are such effects reflexive, automatic features of visual processing? Or might they instead arise only as contingent strategies in tasks in which subjects must interact with (and thus focus on the features of) such objects? We explored these questions in an especially direct way—by embedding such displays into the background of a completely independent “foraging” task. Subjects now moved their disc to collect small “food” dots (which appeared sequentially in random locations) as quickly as possible. The darts were task-irrelevant, and subjects were encouraged to ignore them. Nevertheless, foraging was impaired when the randomly moving darts pointed at the subjects’ disc, as compared to control conditions in which they were either oriented orthogonally to the subjects’ disc or pointed at another moving shape—thereby controlling for nonsocial factors. The perception of animacy thus influences downstream visuomotor behavior in an automatic manner, such that subjects cannot completely override the influences of seemingly animate shapes even while attempting to ignore them.     

Intelligence, reaction time (RT) and a new ‘odd-man-out’ RT paradigm

A sample of adult Ss of reasonably normal intelligence were given an ‘IQ’ test, a series of RT tests using 0, 1, 2, 3 bits of information in a Hick paradigm and an RT task requiring choice of 1 of 3 lights as an ‘odd-man-out’ on the basis of its relative position. Negative correlations were found between both RT and measures of variation in RT and ‘IQ’ for both of the two tasks. Recent results showing no correlation between Hick slope and ‘IQ’ and no increase in correlation between ‘IQ’ and RT with increasing number of bits, are confirmed. An explanation for findings of Ss whose RT data do not conform to Hick's law is tested and found inadequate. The ‘odd-man-out’ task is found to show an effect of ‘learning’ across the period of the task, the size of the learning effect was found also to correlate with ‘IQ’, but no evidence for learning was found with the choice RT task.     

Chasing vs. stalking: interrupting the perception of animacy

Visual experience involves not only physical features such as color and shape, but also higher-level properties such as animacy and goal-directedness. Perceiving animacy is an inherently dynamic experience, in part because agents' goal-directed behavior may be frequently in flux-unlike many of their physical properties. How does the visual system maintain and update representations of agents' animate and goal-directed behavior over time and motion? The present study explored this question in the context of a particularly salient form of perceived animacy: chasing, in which one shape (the "wolf") pursues another shape (the "sheep"). Here the participants themselves controlled the movement of the sheep, and the perception of chasing was assessed in terms of their ability to avoid being caught by the wolf-which looked identical to many moving distractors, and so could be identified only by its motion. The wolf's pursuit was frequently interrupted by periods in which it was static, jiggling in place, or moving randomly (amidst distractors that behaved similarly). Only the latter condition greatly impaired the detection of chasing-and only when the random motion was grouped into temporally extended chunks. These results reveal (1) how the detection of chasing is determined by the character and temporal grouping (rather than just the brute amount) of "pursuit" over time; and (2) how these temporal dynamics can lead the visual system to either construct or actively reject interpretations of chasing.     

Schizotypy and hemisphere function—II : Performance asymmetry on a verbal divided visual-field task

Following reports that psychotic patients show abnormal performance asymmetries on divided visual-field (DVF) tasks, a study was made of the relationship between performance asymmetries on a verbal DVF task in a group of normal Ss (18 male, 18 female) and self-report measures of personality. Interest was focused primarily on a new questionnaire, the STQ, which purports to provide measures of both ‘schizotypal’ and ‘borderline’ personality. It was hypothesized that high scoring on the ‘schizotypal’ scale would be associated with attenuation of performance asymmetry on the DVF task. The hypothesized correlation was found for males but not for females. The results are discussed in the context of theoretical issues central to the DVF method and are taken generally to support a continuity model of psychosis.     

Understanding intention from minimal displays of human activity

The impression of animacy from the motion of simple shapes typically relies on synthetically defined motion patterns resulting in pseudorepresentations of human movement. Thus, it is unclear how these synthetic motions relate to actual biological agents. To clarify this relationship, we introduce a novel approach that uses video processing to reduce full-video displays of human interactions to animacy displays, thus creating animate shapes whose motions are directly derived from human actions. Furthermore, this technique facilitates the comparison of interactions in animacy displays from different viewpoints-an area that has yet to be researched. We introduce two experiments in which animacy displays were created showing six dyadic interactions from two viewpoints, incorporating cues altering the quantity of the visual information available. With a six-alternative forced choice task, results indicate that animacy displays can be created via this naturalistic technique and reveal a previously unreported advantage for viewing intentional motion from an overhead viewpoint.     

The Cognitive Architecture of Perceived Animacy: Intention,Attention, and Memory

Human vision supports social perception by efficiently detecting agents and extracting rich information about their actions, goals, and intentions. Here, we explore the cognitive architecture of perceived animacy by constructing Bayesian models that integrate domain‐specific hypotheses of social agency with domain‐general cognitive constraints on sensory, memory, and attentional processing. Our model posits that perceived animacy combines a bottom–up, feature‐based, parallel search for goal‐directed movements with a top–down selection process for intent inference. The interaction of these architecturally distinct processes makes perceived animacy fast, flexible, and yet cognitively efficient. In the context of chasing, in which a predator (the “wolf”) pursues a prey (the “sheep”), our model addresses the computational challenge of identifying target agents among varying numbers of distractor objects, despite a quadratic increase in the number of possible interactions as more objects appear in a scene. By comparing modeling results with human psychophysics in several studies, we show that the effectiveness and efficiency of human perceived animacy can be explained by a Bayesian ideal observer model with realistic cognitive constraints. These results provide an understanding of perceived animacy at the algorithmic level—how it is achieved by cognitive mechanisms such as attention and working memory, and how it can be integrated with higher‐level reasoning about social agency.     

The Ambiguity of Quantifiers

In the tradition of substructural logics, it has been claimed for a long time that conjunction and inclusive disjunction are ambiguous:we should, in fact, distinguish between ‘lattice’ connectives (also called additive or extensional) and ‘group’ connectives (also called multiplicative or intensional). We argue that an analogous ambiguity affects the quantifiers. Moreover, we show how such a perspective could yield solutions for two well-known logical puzzles: McGee’s counterexample to modus ponens and the lottery paradox.     

孤独症谱系障碍者基于运动线索的生命知觉

生命知觉是人们将客体自动加工为可以相互作用的生命体的认知过程。ASD者基于运动线索的生命知觉的研究方法包括追逐检测范式、运动特性参数化范式和因果知觉范例。其生命知觉的异常主要表现为运动信息整合能力不足、社会因果知觉缺陷以及对高复杂度运动的神经追踪较弱。相关理论假设从神经病理、认知加工及脑结构和功能障碍层面进行解释。未来应提升研究方法的生态效度,推进追踪与系统化研究,促进相关干预方案的开发。     

‘Chasing' in gambling behavior: personality and cognitive determinants

The phenomenon of ‘chasing' has been identified as one of the central characteristics of the behavior of pathological gamblers [American Psychiatric Association (1994). Diagnostic and statistical manual of mental disorders (4th ed., DSM IV). Washington, DC: APA]. It consists of more frequent involvement, increased persistence and elevated monetary risk in an effort to recoup money that has been lost. The present research makes a distinction between within- and between-session chasing, and attempts to examine the determinants of within-session chasing in a reasonably valid laboratory analogue. Male college students who gambled (N=248) were given US$10 and an opportunity to gamble. They could: (1) decline to gamble and keep their US$10 (nonplayers); (2) gamble and win even more money by quitting at a more optimal time (nonchasers); or (3) gamble longer than they should, resulting in the loss of all available money (chasers). Zuckerman's impulsivity factor (from the ZKPQ) discriminated chasers from nonchasers. Breen and Zuckerman's Gambling Beliefs and Attitudes Survey (GABS) discriminated players from nonplayers. A sensation-seeking explanation of within-session chasing was not supported. The results are discussed in terms of the impact of impulsivity on within-session chasing. It is suggested that the GABS may serve as a general measure of ‘affinity' to gambling, and could be useful in examining the process of between-session chasing, that is, returning on another day to ‘get even'.     

The influence of mirror reversals on male and female performance in spatial tasks: A componential look

O'Boyle and Hoff (Neuropsychologia, 25, 977–982, 1987) reported that females were faster and more accurate than males at mirror-tracing the outline of random shapes. To account for this differential performance, the authors advanced two alternative explanations. The first was a ‘Spatial Stroop’ effect which suggested that, because of their enhanced spatial ability, males are especially disadvantaged in escaping the misleading visual feedback provided by the mirror, resulting in slower and less accurate tracings. The second was a ‘manipulospatial’ hypothesis which suggested that the tracing advantage was related to female superiority in fine-detailed motor control, and perhaps, differential practice at performing skilled motor tasks in mirror-reversed contexts. In the present study, two experiments were conducted to assess the relative viability of these explanations. In Experiment 1, the WAIS-R Block Design task was performed within and outside the context of a mirror. This was done to determine if the observed female advantage was restricted to mirror-tracing per se, or generalizable to other manipulospatial tasks. In Experiment 2, a mental rotation task was performed within and outside the context of a mirror. The latter was designed to reveal if the removal of the motor component would affect the obtained sex difference. The present findings suggest that as long as some form of precision motor manipulation is required, females are superior to males at mirror-reversed spatial tasks. However, when the motor component is eliminated, a male performance advantage emerges in both normal and mirror-reversed contexts, suggesting that the manipulospatial hypothesis is the more viable explanation.     

Love and anarchy in Romania : A critical review of Mircea Eliade's Autobiography, volume one, 1907–1937

Eliade is a problem: to at least half of today's historians of religion he embodies the discipline; to the other half he is anathema. I do not intend to review this debate here, nor to rehearse the themes of Eliade's massive oeuvre. I will, however, point over my shoulder to the mixed legacy of theoretical debts and doubts Eliade's work has inspired and try to bring them into relationship with the life story Eliade tells in the Autobiography. This review then attempts to show how Eliade's ‘life’ and ‘letters’ cohere and thus how in illuminating one we shed light on the other.     

Visual enhancement of touch and the bodily self

We experience our own body through both touch and vision. We further see that others’ bodies are similar to our own body, but we have no direct experience of touch on others’ bodies. Therefore, relations between vision and touch are important for the sense of self and for mental representation of one’s own body. For example, seeing the hand improves tactile acuity on the hand, compared to seeing a non-hand object. While several studies have demonstrated this visual enhancement of touch (VET) effect, its relation to the ‘bodily self’, or mental representation of one’s own body remains unclear. We examined whether VET is an effect of seeing a hand, or of seeing my hand, using the rubber hand illusion. In this illusion, a prosthetic hand which is brushed synchronously—but not asynchronously—with one’s own hand is felt to actually be one’s hand. Thus, we manipulated whether or not participants felt like they were looking directly at their hand, while holding the actual stimulus they viewed constant. Tactile acuity was measured by having participants judge the orientation of square-wave gratings. Two characteristic effects of VET were observed: (1) cross-modal enhancement from seeing the hand was inversely related to overall tactile acuity, and (2) participants near sensory threshold showed significant improvement following synchronous stroking, compared to asynchronous stroking or no stroking at all. These results demonstrate a clear functional relation between the bodily self and basic tactile perception.     

Inverse effectiveness, multisensory integration, and the bodily self: Some statistical considerations

A recent report in Consciousness and Cognition provided evidence from a study of the rubber hand illusion (RHI) that supports the multisensory principle of inverse effectiveness (PoIE). I describe two methods of assessing the principle of inverse effectiveness (‘a priori’ and ‘post-hoc’), and discuss how the post-hoc method is affected by the statistical artefact of ‘regression towards the mean’. I identify several cases where this artefact may have affected particular conclusions about the PoIE, and relate these to the historical origins of ‘regression towards the mean’. Although the conclusions of the recent report may not have been grossly affected, some of the inferential statistics were almost certainly biased by the methods used. I conclude that, unless such artefacts are fully dealt with in the future, and unless the statistical methods for assessing the PoIE evolve, strong evidence in support of the PoIE will remain lacking.     

Schizotypy and hemisphere function—I : Theoretical considerations and the measurement of schizotypy

This paper brings together, in the context of individual-differences theory, two developing themes in schizophrenia research. One concerns the manifestation, in normal people, of ‘psychotic’ characteristics and their measurement using scales which, unlike the Eysenck P scale, draw their items from the clinical symptomatology of psychosis. Recent work on the so-called ‘borderline states’ is considered especially relevant and a new two-scale questionnaire (STQ) is described which was modelled on the current distinction, in DSM-III, between ‘schizotypal personality disorder’ and ‘borderline personality disorder’. The second theme addressed concerns the possible biological basis of individual differences in ‘schizotypy’. It is argued, in the light of some emerging views about the nature of schizophrenia, that this may lie in the functional and structural properties of hemisphere organization. A suggested strategy for evaluating this theory is an examination of the performance of schizotypal normal Ss on tests of hemisphere function.     

Lexical access in early stages of visual word processing: A single-trial correlational MEG study of heteronym recognition

We present an MEG study of heteronym recognition, aiming to distinguish between two theories of lexical access: the ‘early access’ theory, which entails that lexical access occurs at early (pre 200 ms) stages of processing, and the ‘late access’ theory, which interprets this early activity as orthographic word-form identification rather than genuine lexical access. A correlational analysis method was employed to examine effects of the heteronyms’ form and lexical properties on brain activity. We find support for the ‘late access’ view, in that lexical properties did not affect processing until after 300 ms, while earlier activation was primarily modulated by orthographic form.