The effects of flicker on eye movement control

Groups of typists with extensive experience of screen-based editing and groups of students with no such experience carried out a reading task under three conditions of illumination (50-Hz flicker, 100-Hz flicker, and steady illumination). Subjects read a sentence, which was followed by the presentation of a single stimulus word on the same line to the right-hand side of the display. The task was to decide whether or not the stimulus was present in the sentence. Subjects were free to re-inspect the sentence when making the decision. Eye movements were measured as subjects completed the task. In comparison with students, typists adopted a more cautious reading style, making more right-to-left saccades, shorter saccades, and more corrective eye movements. Flicker affected the performance of both groups of subjects in the first pass, leading to shorter saccades. In the second pass, its effect for students was to shorten the extent of large saccades made to check the presence of the stimulus word. In the group of typists, flicker led to an increase in the variability of saccade extent and a doubling in the number of small corrective saccades. The results are consistent with the view that flicker has two distinct effects on reading, both of which are potentially disruptive. The first relates to an increase in the number of prematurely triggered saccades, which are, as a result, less accurate. The second is an increase in the number of saccades perturbed in flight, which land short of their intended target. These two mechanisms may have different consequences for readers, depending on their reading style.     

Prior Mental Disorders and Lifetime Suicidal Behaviors Among US Army Soldiers in the Army Study to Assess Risk and Resilience in Servicemembers (Army STARRS)

We report on associations of retrospectively reported temporally prior mental disorders and Army career characteristics with subsequent first onset of suicidal behaviors in a large, representative sample of US Army soldiers who participated in the Consolidated All‐Army Survey of the Army Study to Assess Risk and Resilience in Servicemembers (N = 29,982). Results reveal that among men and women, all self‐reported lifetime disorders measured (some assessed with screening scales) are associated with subsequent onset of suicide ideation. Among men, three disorders characterized by agitation and impulsiveness (intermittent explosive disorder, panic disorder, and substance disorders) predict the transition from suicide ideation to attempt. For both men and women, being in the Regular Army (vs. National Guard or Army Reserve) predicts suicide attempts in the total sample. For men, a history of deployment and junior rank are predictors of suicide attempts after adjusting for preenlistment disorders but not accounting for pre‐ and postenlistment disorders, suggesting that postenlistment disorders account for some of the increased suicide risk among these career characteristics. Overall, these results highlight associations between mental disorders and suicidal behaviors, but underscore limitations predicting which people with ideation attempt suicide.     

Context modulation of US signal value

Context modulation of unconditioned stimulus (US) signal value was examined in two experiments. In Experiment 1, rats showed significantly more magazine entries after a single food pellet US in Context A (in which three additional pellets shortly followed) than in Context B (in which the delivery of three additional pellets was delayed). Experiment 2 replicated this effect and showed that any differences in contextual associative strength at the time the single food pellet was delivered did not importantly contribute to context modulation. Implications for theories of occasion setting and context modulation are considered.