Etiquette and effort: holding doors for others.

Etiquette, the customary code of polite behavior among members of a group, provides a means of conveying respect for others, but what is the basis for etiquette's unwritten rules? Here we show that one form of etiquette, holding a door open for another person, reflects the door holder's expectation that the person for whom he or she holds the door shares the belief that the total effort expended by the two of them will be less than the summed efforts of the two individuals acting on their own. Our observations extend recent work on effort reduction in motor control to the management of social interactions.

Psychologically distinct classes of motor behavior inferred from individual differences: evidence from a sequential stacking task.

A number of studies have demonstrated regularities in how individuals select and perform single object manipulations, but little work has been concerned with the manipulation of multiple objects. To this end, the authors asked participants to stack a set of linearly spaced containers onto various goal locations. Our aim was to determine whether participants adopted specific strategies to complete this task. We focused on whether the distance between the objects, the goal location of the objects, or both, determined the classes of movement sequences that individuals used to perform the task. The results showed that some individuals tended to use one hand for lifting and releasing the containers whereas other individuals tended to use both hands for lifting and releasing the containers. Those participants who tended to use one hand varied which hand was used according to the goal location of the containers but not the distance between containers. The emergence of these individual differences provides a new basis for inferring psychologically distinct classes of motor behavior.