Facilitation of arm movements by their outcome desirability

A large body of research suggests arm extension and arm flexion to be indicators of automatically generated withdrawal and approach motivation, respectively. However, such a view has not remained unchallenged. Recent research suggests that the motivational significance of arm movements may be largely context dependent. The aim of this research was to demonstrate that an essential facilitating context factor for arm movements relies on the desirability of their expected outcomes. Participants viewed negative and positive stimulus material (pictures and words) and were asked to concurrently perform either an arm extension or an arm flexion. Arm movements were embedded in a meaningful context, leading to a stimulus size decrease or increase; and thus giving the visual illusion of withdrawing from the stimulus or approaching it. Results show that the significance of arm movements is indeed influenced by the desirability of their respective effects.

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Stimulus size and the magnitude of the visual illusion of extent

Human Physiology ◽

10.1134/s0362119710020064 ◽

2010 ◽

Vol 36 (2) ◽

pp. 164-171 ◽

Cited By ~ 3

Author(s):

A. Bulatov ◽

A. Bertulis ◽

A. Gutauskas ◽

N. Bulatova

Keyword(s):

Visual Illusion ◽

Stimulus Size ◽

Visual Illusion Of Extent

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Behavioural Contrast Does Not Occur with Continuous Reinforcement in the Positive Component

Quarterly Journal of Experimental Psychology ◽

10.1080/14640747608400540 ◽

1976 ◽

Vol 28 (1) ◽

pp. 77-82 ◽

Cited By ~ 3

Author(s):

John W. Scull ◽

Euan M. Macphail

Keyword(s):

Large Body ◽

Positive Contrast ◽

Positive Stimulus ◽

Control Group ◽

Positive Component ◽

Continuous Reinforcement ◽

Discrimination Group

An experiment reported by Jenkins (1961) obtained positive behavioural contrast in a discrimination with continuous reinforcement of the positive stimulus. A large body of research, however, has failed to obtain positive contrast with this type of schedule. Jenkins's experiment was repeated with an added control group matched to the discrimination group in number of nonreinforced components. No positive contrast was obtained, and it was concluded that Jenkins's result could not be interpreted as positive contrast. The implications of this result for some theoretical accounts of positive contrast were discussed.

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Muscle effort is best minimized by the right-dominant arm in the gravity field

10.1101/2021.07.13.452146 ◽

2021 ◽

Author(s):

Gabriel Poirier ◽

Melanie Lebigre ◽

France Mourey ◽

Charalambos Papaxanthis ◽

Jeremie Gaveau

Keyword(s):

Motor System ◽

Large Body ◽

Arm Movements ◽

Muscular Activity ◽

Open Loop ◽

Electromyographic Activity ◽

Loop Control ◽

Gravity Effects ◽

Directional Asymmetries ◽

The Right

The central nervous system (CNS) is thought to develop motor strategies that minimize various hidden criteria, such as end-point variance or effort. A large body of literature suggests that the dominant arm is specialized for such open-loop optimization-like processes whilst the non-dominant arm is specialized for closed-loop control. Building on recent results suggesting that the brain plans arm movements that takes advantage of gravity effects to minimize muscle effort, the present study tests the hypothesized superiority of the dominant arm motor system for effort minimization. Thirty participants (22.5 ± 2.1 years old; all right-handed) performed vertical arm movements between two targets (40° amplitude), in two directions (upwards and downwards) with their two arms (dominant and non-dominant). We recorded the arm kinematics and the electromyographic activity of the anterior and posterior deltoid to compare two motor signatures of the gravity-related optimization process; i.e., directional asymmetries and negative epochs on phasic muscular activity. We found that these motor signatures were still present during movements performed with the non-dominant arm, indicating that the effort-minimization process also occurs for the non-dominant motor system. However, these markers were reduced compared with movements performed with the dominant arm. This difference was especially prominent during downward movements, where the optimization of gravity effects occurs early in the movement. Assuming that the dominant arm is optimal to minimize muscle effort, as suggested by previous studies, the present results support the hypothesized superiority of the dominant arm motor system for effort-minimization.

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Using the research on intergroup conflict in nonhuman animals to help inform patterns of human intergroup conflict

Behavioral and Brain Sciences ◽

10.1017/s0140525x19000827 ◽

2019 ◽

Vol 42 ◽

Author(s):

Amanda R. Ridley ◽

Melanie O. Mirville

Keyword(s):

Large Body ◽

Nonhuman Animal ◽

Intergroup Conflict ◽

Costs And Benefits ◽

Animal Groups ◽

Interesting Article ◽

Nonhuman Animals

Abstract There is a large body of research on conflict in nonhuman animal groups that measures the costs and benefits of intergroup conflict, and we suggest that much of this evidence is missing from De Dreu and Gross's interesting article. It is a shame this work has been missed, because it provides evidence for interesting ideas put forward in the article.

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