Mid Sweden University

The difference in dynamics of resource allocation to pictures of spiders and pictures of other animals in spider fearful participants was investigated. The tasks of the participants were to respond rapidly and accurately to various probe stimuli superimposed on pictures of different animals. These were supposedly fear-relevant (spiders, snakes, and wolfs) and fear-irrelevant (beetles, turtles, and rabbits). The probes were exposed at different stimulus onset asynchronies (SOAs) from picture onset to address the dynamics of resource allocation. The results showed a larger allocation of resources to spider pictures than to pictures of other animals and the resource allocation showed differences depending on task and dependent measure.

In two visual search experiments, the impact of distractor sets on fear relevant stimuli was investigated.  A search set with spiders, snakes, flowers, and mushrooms was compared to a search set with spiders, snakes, rabbits, and turtles. Speeded responses to spider and snake targets were found when flowers and mushrooms served as distractors, but no such effect occurred with rabbit and turtle distractors. In Experiment 2, spider sensitive individuals were compared to non-fearful individuals. Spider sensitive individuals responded faster to spider targets than did non-fearful individuals, but only in the set with flowers and mushrooms.  When using rabbit and turtle distractors, spider sensitive individuals did not show any speeded responses to their feared animal. These results indicate that behavioural expressions of the visual search task depends not only on the individual’s relationship to the stimuli included in a search set, but also on the context in which feared or fear relevant objects are presented.

Influences of a concurrent cognitive demand on allocation of attentional resources and physiological responses to threatening stimuli was investigated. In two secondary task experiments, pictures of fear-relevant and fear-irrelevant stimuli (Experiment 1), as well as feared and non-feared stimuli (Experiment 2), were used as backgrounds in a discrimination task. The cognitive manipulation was provided by a constraint, induced with a threat of punishment motivating participants to respond quick and accurately. The control condition imposed no such constraint. Results showed a larger allocation of attentional resources for both fear-relevant and feared stimuli. More importantly, it was also shown that resources allocated to threatening stimuli could be manipulated by a concurrent cognitive demand. However, both response accuracy and physiological reactions persisted the manipulation when a feared versus a non-feared animal was shown, indicating that attentional resources can be manipulated by an internal cognitive demand even though a fear reaction occurs.