Matthew Ray

Response Selection During a Joint Action Task

ABSTRACT It has been suggested that a shared task representation is used to predict a coactors’ needs and that these predictions influence each coactors response selection in a joint action task. The authors tested this idea using a joint action task in which participants passed a jug to a confederate under different conditions. They hypothesized that if participants predicted the needs of their coactor and planned their movement according to these predictions, the jug would be passed with the handle available to the confederate. Consistent with this hypothesis, the jug was passed with the handle available on 86% of the trials. This strategy may be adopted to improve the efficiency of the whole task as opposed to each individuals portion of the task.

Does Joe influence Fred's action? Not if Fred has autism spectrum disorder.

It has been proposed that the deficits in social interaction seen in autism spectrum disorder (ASD) arise from problems in action perception stemming from a dysfunction of the mirror neuron system (MNS)--a neural network that becomes active during the performance and observation of action. A dysfunction of this system could have a cascading effect leading to deficits in social cognition because poor activation of the MNS during action observation may lead to an incomplete understanding of another persons actions, intentions and, ultimately, mental states. The present study tested the MNS dysfunction explanation by determining if people with ASD demonstrate a between-person inhibition of return (BP-IOR) effect. The BP-IOR effect, longer reaction times to targets presented at the location of another persons previous response relative to an unresponded-to location, has been hypothesized to be the result of the MNS co-representing the observed response and subsequently activating the mechanisms that cause IOR when individuals respond on their own (within-person IOR [WP-IOR]). Consistent with the MNS dysfunction hypothesis, participants with ASD did not demonstrate a BP-IOR effect in a condition in which they only observed the movement of the partner. The participants with ASD did demonstrate a WP-IOR effect suggesting that the mechanisms underlying IOR are intact in ASD. The contrast between the BP- and WP-IOR effects in the participants with ASD provides significant behavioural evidence for MNS dysfunction in ASD and has important implications for understanding this disorder.

Joint Simon Effects in Extrapersonal Space

ABSTRACT Numerous studies have revealed that when people sit next to each other and complete separate parts of a Simon task, response times are shorter when the participants’ stimulus appears in front of them than when the stimulus appears in the opposite side of space. According to the action co-representation account of this joint Simon effect (JSE), participants represent each others responses and the compatibility effects emerge because of a set of facilitatory and inhibitory processes that are similar to those that are activated when individuals perform the entire Simon task alone. D. Guagnano, E. Rusconi, and C. A. Umiltà (2010) argued against this account as the sole mechanism based on their finding that a JSE was not observed when participants sat outside of each others peripersonal space. Notably, the task in the Guagnano et al.s was a modified version of the conventional JSE task designed to increase the independence of the partners. Here, we reconsider the arguments of Guagnano et al. and report a study in which the authors failed to replicate their key finding. Considering the extant JSE literature, we conclude that the null effect in Guagnano et al.s study may be an anomaly and that co-representation remains a leading candidate for the critical process underlying JSEs.

The relationship between the motor system activation during action observation and adaptation in the motor system following repeated action observation.

Repeated action observation has been shown to alter the cortical representation of the observed movement in the motor system. This change in cortical representation is thought to reflect a motor adaptation to observational training (observational training effect). One factor that may impact the observational training effect is the degree of motor system activation that occurs during the observation of the action (i.e., individual differences in the responsiveness of the motor system during action observation). The present study was conducted to test this hypothesis by assessing the relationship between the change in motor system activity during action observation and the change in cortical representation of action following repeated action observation. To this end, transcranial magnetic stimulation (TMS) was used to evoke contractions of thumb muscles in two different protocols: 1) during the observation of thumb movements to assess the responsiveness of each individuals corticospinal system during action observation; and, 2) after the observation of 1800 thumb movements to assess the amount of adaptation in the representation of the thumb following repeated action observation. The key finding was the significant positive relationship between the level of corticospinal system activation during action observation and the amount of change in the direction of TMS evoked thumb movements. These data support the hypothesized relationship between motor system activation during action observation and the motor systems adaptation following observational training. They are also consistent with the notion that a common neural mechanism underlies these effects.

On Mechanisms, Methods, and Measures: A Response to Guagnano, Rusconi, and Umiltà

On Mechanisms, Methods, and Measures: A Response to Guagnano, Rusconi, and Umilta Timothy N. Welsh a b , Dovin Kiernan a , Heather F. Neyedli a , Matthew Ray a , Jay Pratt b & Daniel J. Weeks c a Faculty of Kinesiology and Physical Education , University of Toronto , Ontario , Canada b Department of Psychology , University of Toronto , Ontario , Canada c Department of Psychology , University of Lethbridge , Alberta , Canada Published online: 06 Feb 2013.

Multiple Frames of Reference Are Used During the Selection and Planning of a Sequential Joint Action

Co-actors need to anticipate each others actions to successfully perform joint actions. The frames of reference (FOR) used to simulate a co-actors action could impact what information is anticipated. We hypothesized that co-actors would adopt their co-actors body-centered FOR, even when they do not share the same spatial orientation, so that they could anticipate body-related aspects of their co-actors task. Because it might be beneficial to plan joint actions based on environment and body-centered information, we hypothesized that individuals would utilize multiple FORs during response planning. To test these hypotheses, participants performed a sequential aiming task where the goal was to move a wooden dowel to one of four potential targets as quickly and accurately as possible. A cue was presented at the beginning of each trial that was either 25, 50, or 75% valid. Following the cue presentation, the first person to act (initiator) placed the wooden dowel, anywhere they liked, in the workspace. Then, the finisher performed their aiming movement from the location that the initiator had placed the dowel. The key dependent measure was the dowel placement of the initiator because it provided an index of how much the initiator attempted to facilitate the efficient performance of the finisher. The results revealed that individuals adopted an allocentric FOR (dowel placement was more biased toward cued locations as cue validity increased) and partially adopted their co-actors body-centered FOR (dowel placement was biased toward the finishers body, but not toward the co-actors contralateral space). In conclusion, multiple FORs can be used to anticipate both body- and environment-related information of a co-actors task. It may be difficult, however, for individuals to fully adopt their co-actors body-centered FOR when they have differing orientations.

Trajectory deviations in spatial compatibility tasks with peripheral and central stimuli.

It is widely held that the spatial compatibility effect emerges because the irrelevant spatial dimension of the target stimulus activates a response simultaneous to the activation of a response to the relevant stimulus dimension. The non-target response facilitates response planning on compatible trials, but interferes with response planning on incompatible trials. In support of this hypothesis, the trajectories of aiming movements executed on incompatible trials deviate in the direction of the stimulus location. These deviations are thought to occur because the characteristics of the simultaneously active target and non-target responses merge. Previously, target stimuli were presented at the target locations leaving open the possibility that the response activation and subsequent deviations were dependent on the stimulus-driven attentional capture associated with the dynamic change of stimulus onset. The present research was conducted to determine if attention capturing events at the target locations were necessary for the movement deviations to emerge by investigating if trajectory deviations are also observed when the spatial dimension is presented centrally. Participants in the Central condition aimed to left and right target locations based on the color of a ring worn on a finger that pointed toward the response locations. Similar to results from a Peripheral condition, trajectory deviations were observed in the Central condition. Although it is unclear if the deviations in the Central condition occurred because of attentional shifts driven by the cue or response preplanning, these results demonstrate that dynamic changes at target locations are sufficient, but not necessary, to generate trajectory deviations.