Biomedical subjects

Amelia R Hunt

Publications and source records attributed to Amelia R Hunt.

5 recordsLinked to original sources

PubMed2004

Multisensory executive functioning.

To better understand the prefrontal circuitry that putatively supports executive functions, such as those involved in switching tasks, we asked whether a current task set is open equally to receiving information from any sensory modality or if it is to some degree modality-specific. Subjects were presented with a sequence of digits to be classified as either odd/even or greater/less than five. The digits were either auditory or visual, with the modality varying randomly. Results demonstrated a reaction time (RT) cost associated with switching between tasks and also an unexpected cost of switching between modalities. When both modality and task switched, the two costs were greater than either of the costs alone, but significantly less than predicted simply by summing the two costs together (i.e., they were underadditive). These data indicate that the frontal mechanisms that allow for a switch in task are only partially modality-specific. Current theories of executive function must be adapted to account for this finding. We also suggest that the present paradigm is amenable to future research aimed at determining precisely how modalities are linked within a task set.

Acoustic Stimulation↗

PubMed2004

Integration of competing saccade programs.

Reflexive responses are often in direct competition with voluntary control. We test two opposing explanations for how this competition is resolved with respect to eye movements. One states that the quickest activation wins. The other states that the strongest activation wins. We show that an eye movement is executed according to the strongest activation, with the competition being staged at a common subcortical site.

Humans↗

PubMed2003

Covert and overt voluntary attention: linked or independent?

Recent evidence indicates that reflexive shifts in spatial attention with eye movements (overt orienting) and without eye movements (covert orienting) can be dissociated [J. Exp. Psychol. Hum. Percept. Perform., in press]. Here, we show that a similar dissociation exists for voluntary shifts in overt and covert attention. Our study is consistent with general theories of attention that assume bottom-up (reflexive) processes and top-down (voluntary) processes converge on a common neural architecture.

Acoustic Stimulation↗

PubMed2003

Inhibition of return: Dissociating attentional and oculomotor components.

Inhibition of return (IOR) describes a performance decrement for stimuli appearing at recently cued locations. Both attentional and motor processes have been implicated in the IOR effect. The present data reveal a double dissociation between the attentional and motor components of IOR whereby the motor-based component of IOR is present when the response is oculomotor, and the attention-based component of IOR is present when the response is manual. These 2 distinct components should be considered and studied separately, as well as in relation to each other, if a comprehensive theory of IOR is to be achieved. ((c) 2003 APA, all rights reserved)

Adult↗

PubMed2002

Eliminating the cost of task set reconfiguration.

With insufficient time to fully prepare for a switch in task, a deterioration in performance on the first trial of a new task would be expected. The interest of researchers has been captured by the residual switch costs that, surprisingly, remain despite sufficient time to prepare. We used avery simple task to investigate the costs to reaction time and accuracy associated with changing between two different instructional sets every eight trials. Subjects responded to left and right visual targets by making either spatially compatible or incompatible eye movements (Experiment 1) or buttonpress responses (Experiment 2). The subjects were cued as to whether to make the compatible or the incompatible response by the color of a border appearing on the perimeter of the display. In cases in which the subject alternated between making pro- and antisaccades, the large costs to reaction time and accuracy at the short cue-target stimulus onset asynchrony were completely eliminated when sufficient time was provided to prepare for the switch. This complete elimination of residual switch costs was not obtained when the same alternation was applied to manual responses. This pattern of results links residual costs to response selection processes and suggests that they are not a necessary component of the switch process. We propose that the elimination of "stubborn" residual switch costs is rooted in our use of a hypercompatible task (making saccades toward targets) that places minimal demands on response selection.

Form Perception↗