Effects of agency on movement interference during observation of a moving dot stimulus

Human movement performance is subject to interference if the performer simultaneously observes an incongruent action. It has been proposed that this phenomenon is due to motor contagion during simultaneous movement performance-observation, with coactivation of shared action performance and action observation circuitry in the premotor cortex. The present experiments compared the interference effect during observation of a moving person with observation of moving dot stimuli: The dot display followed either a biologically plausible or implausible velocity profile. Interference effects due to dot observation were present for both biological and nonbiological velocity profiles when the participants were informed that they were observing prerecorded human movement and were absent when the dot motion was described as computer generated. These results suggest that the observer's belief regarding the origin of the dot motion (human-computer generated) modulates the processing of the dot movement stimuli on their later integration within the motor system, such that the belief regarding their biological origin is a more important determinant of interference effects than the stimulus kinematics.     

How does visuomotor priming differ for biological and non-biological stimuli? A review of the evidence

Visuomotor priming occurs when our actions are influenced by observing a compatible or incompatible action. Here we ask whether visuomotor priming is specific to human, biological actions or generalises to non-biological movements, such as abstract shapes or robots. Reviewing the evidence indicates that priming occurs for both types of stimuli and emphasises the contributions of both bottom-up (e.g. stimulus saliency, appearance, kinematics) and top-down (e.g. attention and prior knowledge) factors. We propose a model suggesting that although bottom-up features play a critical role, the degree of difference in priming for biological versus non-biological stimuli can be ultimately shaped by top-down factors.     

Recall and recognition of order and item information in probed running memory, as a function of IQ

Two experiments were designed to test the possibility that correlations between IQ and probed serial running memory depend on IQ-related individual differences in the retention of order information in short-term memory. In Experiment I, correlations were obtained regardless of whether instructions emphasized serial recall or free recall. In Experiment II, a significant correlation between IQ and performance was obtained in a recognition test for very recent item information, but not in a recognition test for very recent order information. These data together with a theoretical analysis of the operations involved in the tasks, led to the conclusion that the correlations reflected individual differences in the capacity to access specified sets of items in very short-term memory.     

Eye-hand interactions in tracing and drawing tasks

We report a preliminary analysis of the interactions between eye and hand during tracing and drawing of four simple shapes. Eye and hand movements were recorded using the ASL 504 system and the Flock of Birds system, respectively. During tracing, pen tip and eye were tightly coupled, with participants making a series of small saccades just in front of the moving pen, interspersed with periods of smooth pursuit. During drawing, saccades were fewer and larger and pursuit was less frequent. Observed eye-hand interactions suggested a bidirectional relationship between the eye and hand. These findings are explained in terms of the differing degree that the two tasks employ visual detail, external or internal cues and eye-hand coordination.     

Upper- and lower-limb amputees show reduced levels of eeriness for images of prosthetic hands

Psychonomic Bulletin & Review - The “uncanny phenomenon” describes the feeling of unease associated with seeing an image that is close to appearing human. Prosthetic hands in...     

Action observation produces motor resonance in Parkinson's disease

Observation of movement activates the observer's own motor system, influencing the performance of actions and facilitating social interaction. This motor resonance is demonstrated behaviourally through visuomotor priming, whereby response latencies are influenced by the compatibility between an intended action and an observed (task‐irrelevant) action. The impact of movement disorders such as Parkinson's disease (PD) on motor resonance is unclear, as previous studies of visuomotor priming have not separated imitative compatibility (specific to human movement) from general stimulus‐response compatibility effects. We examined visuomotor priming in 23 participants with mild‐to‐moderate PD and 24 healthy older adults, using a task that pitted imitative compatibility against general stimulus‐response compatibility. Participants made a key press after observing a task‐irrelevant moving human finger or rectangle that was either compatible or incompatible with their response. Imitative compatibility effects, rather than general stimulus‐response compatibility effects, were found specifically for the human finger. Moreover, imitative compatibility effects did not differ between groups, indicating intact motor resonance in the PD group. These findings constitute the first unambiguous demonstration of imitative priming in both PD and healthy ageing, and have implications for therapeutic techniques to facilitate action, as well as the understanding of social cognition in PD.     

Exploring visuomotor priming following biological and non-biological stimuli

Observation of human actions influences the observer’s own motor system, termed visuomotor priming, and is believed to be caused by automatic activation of mirror neurons. Evidence suggests that priming effects are larger for biological (human) as opposed to non-biological (object) stimuli and enhanced when viewing stimuli in mirror compared to anatomical orientation. However, there is conflicting evidence concerning the extent of differences between biological and non-biological stimuli, which may be due to stimulus related confounds. Over three experiments, we compared how visuomotor priming for biological and non-biological stimuli was affected over views, over time and when attention to the moving stimulus was manipulated. The results indicated that the strength of priming for the two stimulus types was dependent on attentional location and load. This highlights that visuomotor priming is not an automatic process and provides a possible explanation for conflicting evidence regarding the differential effects of biological and non-biological stimuli.