Temporal perception is enhanced for goal-directed biological actions

ABSTRACT

Research into the visual perception of goal-directed human action indicates that human action perception makes use of specialized processing systems, similar to those that operate in visual expertise. Against this background, the current research investigated whether perception of temporal information in goal-directed human action is enhanced relative to similar motion stimuli. Experiment 1 compared observers’ sensitivity to speed changes in upright human action to a kinematic control (an animation yoked to the motion of the human hand), and also to inverted human action. Experiment 2 compared human action to a non-human motion control (a tool moved the object). In both experiments observers’ sensitivity to detecting the speed changes was higher for the human stimuli relative to the control stimuli, and inversion in Experiment 1 did not alter observers’ sensitivity. Experiment 3 compared observers’ sensitivity to speed changes in goal-directed human and dog actions, in order to determine if enhanced temporal perception is unique to human actions. Results revealed no difference between human and dog stimuli, indicating that enhanced speed perception may exist for any biological motion. Results are discussed with reference to theories of biological motion perception and perception in visual expertise.     

Neural correlates of the perception of goal-directed action in infants

We investigated the neural correlates of the perception of human goal-directed action by 8-month-old infants. Infants viewed video loops of complete and incomplete actions, which they could discriminate according to our pilot study, while we recorded their electrophysiological brain activity. Analysis of bursts of gamma-band oscillations resulting from passive viewing of these stimuli indicated increased gamma-band activity over left frontal regions when viewing incomplete actions as compared with complete actions. These results suggest that by 8 months infants are sensitive to the disruption of perceived goal-directed actions.     

Dissociable neural systems for recognizing emotions

This study tested the hypothesis that the recognition of emotions would draw upon anatomically separable brain regions, depending on whether the stimuli were static or explicitly conveyed information regarding actions. We investigated the hypothesis in a rare subject with extensive bilateral brain lesions, patient B., by administering tasks that assessed recognition and naming of emotions from visual and verbal stimuli, some of which depicted actions and some of which did not. B. could not recognize any primary emotion other than happiness, when emotions were shown as static images or given as single verbal labels. By contrast, with the notable exception of disgust, he correctly recognized primary emotions from dynamic displays of facial expressions as well as from stories that described actions. Our findings are consistent with the idea that information about actions is processed in occipitoparietal and dorsal frontal cortices, all of which are intact in B.'s brain. Such information subsequently would be linked to knowledge about emotions that depends on structures mapping somatic states, many of which are also intact in B.'s brain. However, one of these somatosensory structures, the insula, is bilaterally damaged, perhaps accounting for B.'s uniformly impaired recognition of disgust (from both static and action stimuli). Other structures that are damaged in B.'s brain, including bilateral inferior and anterior temporal lobe and medial frontal cortices, appear to be critical for linking perception of static stimuli to recognition of emotions. Thus the retrieval of knowledge regarding emotions draws upon widely distributed and partly distinct sets of neural structures, depending on the attributes of the stimulus.     

Infant perception of causal motion produced by humans and inanimate objects

Both the movements of people and inanimate objects are intimately bound up with physical causality. Furthermore, in contrast to object movements, causal relationships between limb movements controlled by humans and their body displacements uniquely reflect agency and goal-directed actions in support of social causality. To investigate the development of sensitivity to causal movements, we examined the looking behavior of infants between 9 and 18 months of age when viewing movements of humans and objects. We also investigated whether individual differences in gender and gross motor functions may impact the development of the visual preferences for causal movements. In Experiment 1, infants were presented with walking stimuli showing either normal body translation or a “moonwalk” that reversed the horizontal motion of body translations. In Experiment 2, infants were presented with unperformable actions beyond infants’ gross motor functions (i.e., long jump) either with or without ecologically valid body displacement. In Experiment 3, infants were presented with rolling movements of inanimate objects that either complied with or violated physical causality. We found that female infants showed longer looking times to normal walking stimuli than to moonwalk stimuli, but did not differ in their looking time to movements of inanimate objects and unperformable actions. In contrast, male infants did not show sensitivity to causal movement for either category. Additionally, female infants looked longer at social stimuli of human actions than male infants. Under the tested circumstances, our findings indicate that female infants have developed a sensitivity to causal consistency between limb movements and body translations of biological motion, only for actions with previous visual and motor exposures, and demonstrate a preference toward social information.     

The role of cue-response mapping in motorvisual impairment and facilitation: evidence for different roles of action planning and action control in motorvisual dual-task priming

Previous research has shown that actions impair the visual perception of categorically action-consistent stimuli. On the other hand, actions can also facilitate the perception of spatially action-consistent stimuli. We suggest that motorvisual impairment is due to action planning processes, while motorvisual facilitation is due to action control mechanisms. This implies that because action planning is sensitive to modulations by cue-response mapping so should motorvisual impairment, while motorvisual facilitation should be insensitive to manipulations of cue-response mapping as is action control. We tested this prediction in three dual-task experiments. The impact of performing left and right key presses on the perception of unrelated, categorically or spatially consistent, stimuli was studied. As expected, we found motorvisual impairment for categorically consistent stimuli and motorvisual facilitation for spatially consistent stimuli. In all experiments, we compared congruent with incongruent cue-key mappings. Mapping manipulations affected motorvisual impairment, but not motorvisual facilitation. The results support our suggestion that motorvisual impairment is due to action planning, and motorvisual facilitation to action control.     

Object-based processes in the planning of goal-directed hand movements

Theories in motor control suggest that the parameters specified during the planning of goal-directed hand movements to a visual target are defined in spatial parameters like direction and amplitude. Recent findings in the visual attention literature, however, argue widely for early object-based selection processes. The present experiments were designed to examine the contributions of object-based and space-based selection processes to the preparation time of goal-directed pointing movements. Therefore, a cue was presented at a specific location. The question addressed was whether the initiation of responses to uncued target stimuli could benefit from being either within the same object (object based) or presented at the same direction (space based). Experiment 1 replicated earlier findings of object-based benefits for non-goal-directed responses. Experiment 2 confirmed earlier findings of space-based benefits for goal-directed hand pointing movements. In Experiments 3 and 4, space-based and object-based manipulations were combined while requiring goal-directed hand pointing movements. The results clearly favour the notion that the selection processes for goal-directed pointing movements are primarily object based. Implications for theories on selective attention and action planning are discussed.     

Visual attention and action: How cueing,direct mapping,and social interactions drive orienting

Despite considerable interest in both action perception and social attention over the last 2 decades, there has been surprisingly little investigation concerning how the manual actions of other humans orient visual attention. The present review draws together studies that have measured the orienting of attention, following observation of another’s goal-directed action. Our review proposes that, in line with the literature on eye gaze, action is a particularly strong orienting cue for the visual system. However, we additionally suggest that action may orient visual attention using mechanisms, which gaze direction does not (i.e., neural direct mapping and corepresentation). Finally, we review the implications of these gaze-independent mechanisms for the study of attention to action. We suggest that our understanding of attention to action may benefit from being studied in the context of joint action paradigms, where the role of higher level action goals and social factors can be investigated.     

Voluntary action influences visual competition

Converging lines of evidence point to a strong link between action and perception. In this study, we show that this linkage plays a role in controlling the dynamics of binocular rivalry, in which two stimuli compete for perceptual awareness. Observers dichoptically viewed two dynamic rival stimuli while moving a computer mouse with one hand. When the motion of one rival stimulus was consistent with observers' own hand movements, dominance durations of that stimulus were extended and, remarkably, suppression durations of that stimulus were abbreviated. Additional measurements revealed that this change in rivalry dynamics was not attributable to observers' knowledge about the condition under test. Thus, self-generated actions can influence the resolution of perceptual conflict, even when the object being controlled falls outside of visual awareness.     

Recognition of biological motion from blurred natural scenes

Biological-motion perception can be regarded as a template-matching process. We are concerned with the visual cues in this template. Biological-motion perception is usually studied with point-light displays similar to the point-light displays invented by Johansson (1973 Perception and Psychophysics 14 201 - 211). These stimuli are in some ways abstract. In order to use more natural stimuli, we recorded movies of different actions in natural scenes. By blurring the scenes we modified the visual cues, particularly the local form and motion information. Observers were asked to identify the action portrayed. Our results demonstrate that templates for biological-motion recognition combine global form and motion cues. Reductions of local form and local motion information by blurring can be compensated by global form change and global motion. Local motion information is also used for segmentation.     

Age-related decrease in recognition of emotional facial and prosodic expressions

The recognition of nonverbal emotional signals and the integration of multimodal emotional information are essential for successful social communication among humans of any age. Whereas prior studies of age dependency in the recognition of emotion often focused on either the prosodic or the facial aspect of nonverbal signals, our purpose was to create a more naturalistic setting by presenting dynamic stimuli under three experimental conditions: auditory, visual, and audiovisual. Eighty-four healthy participants (women = 44, men = 40; age range 20-70 years) were tested for their abilities to recognize emotions either mono- or bimodally on the basis of emotional (happy, alluring, angry, disgusted) and neutral nonverbal stimuli from voice and face. Additionally, we assessed visual and auditory acuity, working memory, verbal intelligence, and emotional intelligence to explore potential explanatory effects of these population parameters on the relationship between age and emotion recognition. Applying unbiased hit rates as performance measure, we analyzed data with linear regression analyses, t tests, and with mediation analyses. We found a linear, age-related decrease in emotion recognition independent of stimulus modality and emotional category. In contrast, the improvement in recognition rates associated with audiovisual integration of bimodal stimuli seems to be maintained over the life span. The reduction in emotion recognition ability at an older age could not be sufficiently explained by age-related decreases in hearing, vision, working memory, and verbal intelligence. These findings suggest alterations in social perception at a level of complexity beyond basic perceptional and cognitive abilities.     

Intentional action processing results from automatic bottom-up attention: An EEG-investigation into the Social Relevance Hypothesis using hypnosis

Social stimuli grab our attention. However, it has rarely been investigated how variations in attention affect the processing of social stimuli, although the answer could help us uncover details of social cognition processes such as action understanding. In the present study, we examined how changes to bottom-up attention affects neural EEG-responses associated with intentional action processing. We induced an increase in bottom-up attention by using hypnosis. We recorded the electroencephalographic μ-wave suppression of hypnotized participants when presented with intentional actions in first and third person perspective in a video-clip paradigm. Previous studies have shown that the μ-rhythm is selectively suppressed both when executing and observing goal-directed motor actions; hence it can be used as a neural signal for intentional action processing. Our results show that neutral hypnotic trance increases μ-suppression in highly suggestible participants when they observe intentional actions. This suggests that social action processing is enhanced when bottom-up attentional processes are predominant. Our findings support the Social Relevance Hypothesis, according to which social action processing is a bottom-up driven attentional process, and can thus be altered as a function of bottom-up processing devoted to a social stimulus.     

Grasping with the eyes: The role of elongation in visual recognition of manipulable objects

Processing within the dorsal visual stream subserves object-directed action, whereas visual object recognition is mediated by the ventral visual stream. Recent findings suggest that the computations performed by the dorsal stream can nevertheless influence object recognition. Little is known, however, about the type of dorsal stream information that is available to assist in object recognition. Here, we present a series of experiments that explored different psychophysical manipulations known to bias the processing of a stimulus toward the dorsal visual stream in order to isolate its contribution to object recognition. We show that elongated-shaped stimuli, regardless of their semantic category and familiarity, when processed by the dorsal stream, elicit visuomotor grasp-related information that affects how we categorize manipulable objects. Elongated stimuli may reduce ambiguity during grasp preparation by providing a coarse cue to hand shaping and orientation that is sufficient to support action planning. We propose that this dorsal-stream-based analysis of elongation along a principal axis is the basis for how the dorsal visual object processing stream can affect categorization of manipulable objects.     

Toward a causal realist account of causal understanding

Within a limited domain, humans can perceive causal relations directly. The term causal realism is used to denote this psychological hypothesis. The domain of causal realism is in actions upon objects and haptic perception of the effects of those actions: When we act upon an object we cannot be mistaken about the fact that we are acting upon it and perceive the causal relation directly through mechanoreceptors. Experiences of actions upon objects give rise to causal knowledge that can be used in the interpretation of perceptual input. Phenomenal causality, the occurrence of causal impressions in visual perception, is a product of the application of acquired causal knowledge in the automatic perceptual interpretation of appropriate stimuli. Causal realism could constitute the foundation on which all causal perception, judgment, inference, attribution, and knowledge develop.     

手近效应：研究内容、影响因素与神经机制

把手放在刺激旁边,会对知觉、记忆、语义和执行控制等认知加工产生影响,这类现象被称为手近效应。手近效应反映了身体与环境的互动对认知的塑造作用,为具身认知提供了新证据。本文从手近效应的内容,影响因素,及其认知、神经机制等方面对相关研究进行梳理。并从手近效应的神经机制,应用研究,以及动作意图和人际社会因素的调节作用等方面探讨当前手近效应还未解决的问题。     

Perception of individuality in bat vocal communication: discrimination between, or recognition of, interaction partners?

Different cognitive processes underlying voice identity perception in humans may have precursors in mammals. A perception of vocal signatures may govern individualised interactions in bats, which comprise species living in complex social structures and are nocturnal, fast-moving mammals. This paper investigates to what extent bats recognise, and discriminate between, individual voices and discusses acoustic features relevant for accomplishing these tasks. In spontaneous presentation and habituation–dishabituation experiments, we investigated how Megaderma lyra perceives and evaluates stimuli consisting of contact call series with individual-specific signatures from either social partners or unknown individuals. Spontaneous presentations of contact call stimuli from social partners or unknown individuals elicited strong, but comparable reactions. In the habituation–dishabituation experiments, bats dishabituated significantly to any new stimulus. However, reactions were less pronounced to a novel stimulus from the bat used for habituation than to stimuli from other bats, irrespective of familiarity, which provides evidence for identity discrimination. A model separately assessing the dissimilarity of stimuli in syllable frequencies, syllable durations and inter-call intervals relative to learned memory templates accounted for the behaviour of the bats. With respect to identity recognition, the spontaneous presentation experiments were not conclusive. However, the habituation–dishabituation experiments suggested that the bats recognised voices of social partners as the reaction to a re-habituation stimulus differed after a dishabituation stimulus from a social partner and an unknown bat.     

Visual perception of musical notation: Registering pitch symbols in memory

Music bears formal relations to language which suggest that perceptual processes in the two modes may also be similar. These experiments examined the way in which experienced musicians differed from non-musicians in their recognition of briefly exposed pitch notation. Experiments I and II together demonstrated that musicians are superior to non-musicians in their immediate written recall of stimuli containing more than three notes, but only when the stimulus is available to them for 150 ms or more. These results are accounted for well by a model proposed by Coltheart (1972) for letter perception under conditions of brief exposure. In this model, two coding processes act simultaneously on the stimulus, one a fast visual coding, and the other a slower, but more permanent abstract (or name) coding. In this case non-musicians appear to be lacking a second, abstract, coding which musicians possess. Experiments III and IV attempted to investigate the nature of the abstract code for musicians by presenting various types of interference in the linguistic or musical mode. Neither concurrent letter naming nor concurrent memorization of pitches appeared to cause a decrement in the original visual task, suggesting that musicians may not have been using simple naming or pitching transformations in coding the visual input.     

Effects of audio-visual integration on the detection of masked speech and non-speech sounds

Integration of simultaneous auditory and visual information about an event can enhance our ability to detect that event. This is particularly evident in the perception of speech, where the articulatory gestures of the speaker's lips and face can significantly improve the listener's detection and identification of the message, especially when that message is presented in a noisy background. Speech is a particularly important example of multisensory integration because of its behavioural relevance to humans and also because brain regions have been identified that appear to be specifically tuned for auditory speech and lip gestures. Previous research has suggested that speech stimuli may have an advantage over other types of auditory stimuli in terms of audio-visual integration. Here, we used a modified adaptive psychophysical staircase approach to compare the influence of congruent visual stimuli (brief movie clips) on the detection of noise-masked auditory speech and non-speech stimuli. We found that congruent visual stimuli significantly improved detection of an auditory stimulus relative to incongruent visual stimuli. This effect, however, was equally apparent for speech and non-speech stimuli. The findings suggest that speech stimuli are not specifically advantaged by audio-visual integration for detection at threshold when compared with other naturalistic sounds.     

The mirror neuron system and action recognition

Mirror neurons, first described in the rostral part of monkey ventral premotor cortex (area F5), discharge both when the animal performs a goal-directed hand action and when it observes another individual performing the same or a similar action. More recently, in the same area mirror neurons responding to the observation of mouth actions have been also found. In humans, through an fMRI study, it has been shown that the observation of actions performed with the hand, the mouth and the foot leads to the activation of different sectors of Broca's area and premotor cortex, according to the effector involved in the observed action, following a somatotopic pattern which resembles the classical motor cortex homunculus. These results strongly support the existence of an execution-observation matching system (mirror neuron system). It has been proposed that this system is involved in action recognition. Experimental evidence in favor of this hypothesis both in the monkey and humans are shortly reviewed.     

Perceived duration decreases with increasing eccentricity

Previous studies examining the influence of stimulus location on temporal perception yield inhomogeneous and contradicting results. Therefore, the aim of the present study is to soundly examine the effect of stimulus eccentricity. In a series of five experiments, subjects compared the duration of foveal disks to disks presented at different retinal eccentricities on the horizontal meridian. The results show that the perceived duration of a visual stimulus declines with increasing eccentricity. The effect was replicated with various stimulus orders (Experiments 1–3), as well as with cortically magnified stimuli (Experiments 4–5), ruling out that the effect was merely caused by different cortical representation sizes. The apparent decreasing duration of stimuli with increasing eccentricity is discussed with respect to current models of time perception, the possible influence of visual attention and respective underlying physiological characteristics of the visual system.     

The role of facial colour and luminance in visual and audiovisual speech perception

We conducted four experiments to investigate the role of colour and luminance information in visual and audiovisual speech perception. In experiments 1a (stimuli presented in quiet conditions) and 1b (stimuli presented in auditory noise), face display types comprised naturalistic colour (NC), grey-scale (GS), and luminance inverted (LI) faces. In experiments 2a (quiet) and 2b (noise), face display types comprised NC, colour inverted (CI), LI, and colour and luminance inverted (CLI) faces. Six syllables and twenty-two words were used to produce auditory and visual speech stimuli. Auditory and visual signals were combined to produce congruent and incongruent audiovisual speech stimuli. Experiments 1a and 1b showed that perception of visual speech, and its influence on identifying the auditory components of congruent and incongruent audiovisual speech, was less for LI than for either NC or GS faces, which produced identical results. Experiments 2a and 2b showed that perception of visual speech, and influences on perception of incongruent auditory speech, was less for LI and CLI faces than for NC and CI faces (which produced identical patterns of performance). Our findings for NC and CI faces suggest that colour is not critical for perception of visual and audiovisual speech. The effect of luminance inversion on performance accuracy was relatively small (5%), which suggests that the luminance information preserved in LI faces is important for the processing of visual and audiovisual speech.