Visual memory for agents and their actions

Humans spend a considerable amount of time remembering other individuals' actions. Nevertheless, it is unclear how the visual system stores information about the identities of agents and their actions. To address this, I used a change detection method where observers were asked to remember agents and the actions they performed. Results show that observers can maintain information about both 2-3 agents and 2-3 actions simultaneously. However, they are highly impaired for remembering which agent performed which action, indicating that agent and action information are retained separately in visual working memory. Further experiments show that agent and action information can be bound together when the visual input contains the appropriate cues. However, this binding process significantly reduces the total amount of information that can be retained. Together, these results show that (1) an additional, resource-demanding process is needed to integrate agent and action information stored in separate working memory stores, and (2) the extent to which these two types of information are bound into integrated units depends largely on the presence of specific cues in the visual input.     

On anxiety-specific actions of tranquilizers

Abstract

This study examined the role of social support in the relationship between work demand and psychological distress (GHQ 12) in correctional officers (N=419), a high stress occupational group. Work demands were positively associated with strain. There was no evidence that social support buffered the negative impact of work demands. Rather, consistent with most previous research findings, support showed direct benefits and these were discussed in the context of worker participation and control. The hypothesis that officers high in negative affectivity, as measured by trait anxiety would show greater reactivity to work demands was not supported. However, trait anxiety appeared to inflate the relationship between work stressors (work demand and work support) and psychological distress supporting recent suggestions that the role of trait anxiety in occupational stress should not be disregarded. Trait anxiety combined additively with work demand to predict individual differences in psychological distress, however social support moderated the impact of trait anxiety on strain.     

On agreed actions without agreed notions

In his plea for consensual democracy in Africa, Kwasi Wiredu recommends unanimity about what is to be done, not what ought to be done, or unanimity on action rather than unanimity of values, beliefs and opinion. I caution the use of this procedural instrument by showing that some issues are so value-laden that a group decision cannot be value-neutral. It may sometimes be more productive to entertain value differences to keep them from going underground and becoming dangerous. However, the ability to locate some common interest or ground seems to be crucial for such value confrontation.     

On the depth reversibility of point-light actions

We investigate the occurrence of perspective reversals for a depth-ambiguous point-light figure. In addition, we exploit the phenomenon of reversibility to search for stimulus features relevant in the process of depth assignment. Experiment 1 shows that perceptual switches indeed occur during prolonged viewing, although the switches occur infrequently. The reversibility is confirmed in Experiment 2, in which the perceptual ambiguity of the point-light action is manipulated as well as observers’ intention to perceive a particular alternative. In addition, the pattern of eye movements reveals local stimulus features specifically associated with the perception of the different alternatives. In Experiment 3, the importance of these features as determining factors of the initial interpretation is investigated by manipulating the location of the first fixation on the stimulus. Implications for a better understanding of biological motion perception are discussed.     

On observing another person's actions: influences of observed inhibition and errors

It was investigated whether an observer would simulate another person's inhibitory and error processes. Two participants sitting next to each other performed a stop signal task in which they occasionally had to try and inhibit their response when indicated to do so by a stop signal. They could either successfully stop the response or fail to stop and, thereby, make an error. An aftereffect of the other person's successful action inhibition and error was obtained: The participants became slower and more accurate when they observed the other person make an error on the previous trial and when they observed a successful stop. The results suggest that observing another person successfully inhibit an action or make an error evokes processes similar to those that occur when these behaviors are produced.     

On fairness and learning agents in a bargaining model with uncertainty

The emergence of fair divisions in a repeated bargaining game is investigated in a computational model. Individuals of human societies often appeal to some norm of fairness in situations where an agreement over the division of a surplus is required. The employed framework consists of players alternating offers that describe possible ways to share a certain commodity. The players are allowed a limited number of offers to reach an agreement; if they fail to agree, the player who made the first offer, the lucky player, wins the whole lot at stake. Uncertainty is introduced in the process by randomly choosing the lucky player at the beginning of each iteration. In the experiments, the players acquired strategies by employing a variant of Q-learning, a reinforcement learning algorithm. Experiments were performed with different configurations of utility functions on the players’ preferences in taking actions in risky situations. Analysis of the results shows that the game theoretical model of a single shot of the bargaining game used in the experiments closely matches the outcomes obtained in the simulated framework, despite the differences in the quality of the players, who are assumed to be fully rational in the theoretical model. Learning agents that are timid toward risky situations manage to acquire strategies that lead to fair outcomes when playing against each other, but find themselves in a disadvantageous position when confronting bolder types.