Time course of oculomotor inhibition revealed by saccade trajectory modulation

Selecting a stimulus as the target for a goal-directed movement involves inhibiting other competing possible responses. Both target and distractor stimuli activate populations of neurons in topographic oculomotor maps such as the superior colliculus. Local inhibitory interconnections between these populations ensure only one saccade target is selected. Suppressing saccades to distractors may additionally involve inhibiting corresponding map regions to bias the local competition. Behavioral evidence of these inhibitory processes comes from the effects of distractors on oculomotor and manual trajectories. Individual saccades may initially deviate either toward or away from a distractor, but the source of this variability has not been investigated. Here we investigate the relation between distractor-related deviation of trajectory and saccade latency. Targets were presented with, or without, distractors, and the deviation of saccade trajectories arising from the presence of distractors was measured. A fixation gap paradigm was used to manipulate latency independently of the influence of competing distractors. Shorter- latency saccades deviated toward distractors and longer-latency saccades deviated away from distractors. The transition between deviation toward or away from distractors occurred at a saccade latency of around 200 ms. This shows that the time course of the inhibitory process involved in distractor related suppression is relatively slow.

A study of factors contributing to late submission of course work

This case study uses log-linear modelling to investigate the interrelationships between factors that may contribute to the late submission of coursework by undergraduate students. A class of 86 computing students are considered. These students were exposed to traditional teaching methods supported by e-learning via a Managed Learning Environment (MLE). The MLE warehouses detailed data about student usage of the various areas of the environment, which can be used to interpret the approach taken to learning. The study investigates the interrelationship between these factors with the information as to whether the student handed in their course work on time or whether they were late. The results from the log-linear modelling technique show that there is an interaction between participating in Discussions within the MLE and the timely submission of course work, indicating that participants are more likely to hand in on time, than those students who do not participate.

The time course of implicit affective picture processing: an eye movement study

Consistent with a negativity bias account, neuroscientific and behavioral evidence demonstrates modulation of even early sensory processes by unpleasant, potentially threat-relevant information. The aim of this research is to assess the extent to which pleasant and unpleasant visual stimuli presented extrafoveally capture attention and impact eye movement control. We report an experiment examining deviations in saccade metrics in the presence of emotional image distractors that are close to a nonemotional target. We additionally manipulate the saccade latency to test when the emotional distractor has its biggest impact on oculomotor control. The results demonstrate that saccade landing position was pulled toward unpleasant distractors, and that this pull was due to the quick saccade responses. Overall, these findings support a negativity bias account of early attentional control and call for the need to consider the time course of motivated attention when affect is implicit

Still feeling it: the time course of emotional recovery from an attentional perspective

Emotional reactivity and the time taken to recover, particularly from negative, stressful, events, are inextricably linked, and both are crucial for maintaining well-being. It is unclear, however, to what extent emotional reactivity during stimulus onset predicts the time course of recovery after stimulus offset. To address this question, 25 participants viewed arousing (negative and positive) and neutral pictures from the International Affective Picture System (IAPS) followed by task-relevant face targets, which were to be gender categorized. Faces were presented early (400–1500 ms) or late (2400–3500 ms) after picture offset to capture the time course of recovery from emotional stimuli. Measures of reaction time (RT), as well as face-locked N170 and P3 components were taken as indicators of the impact of lingering emotion on attentional facilitation or interference. Electrophysiological effects revealed negative and positive images to facilitate face-target processing on the P3 component, regardless of temporal interval. At the individual level, increased reactivity to: (1) negative pictures, quantified as the IAPS picture-locked Late Positive Potential (LPP), predicted larger attentional interference on the face-locked P3 component to faces presented in the late time window after picture offset. (2) Positive pictures, denoted by the LPP, predicted larger facilitation on the face-locked P3 component to faces presented in the earlier time window after picture offset. These results suggest that subsequent processing is still impacted up to 3500 ms after the offset of negative pictures and 1500 ms after the offset of positive pictures for individuals reacting more strongly to these pictures, respectively. Such findings emphasize the importance of individual differences in reactivity when predicting the temporality of emotional recovery. The current experimental model provides a novel basis for future research aiming to identify profiles of adaptive and maladaptive recovery.

The physical pendulum in an advanced undergraduate course in mechanics

The physical pendulum treated with a Hamiltonian formulation is a natural topic for study in a course in advanced classical mechanics. For the past three years, we have been offering a series of problem sets studying this system numerically in our third-year undergraduate courses in mechanics. The problem sets investigate the physics of the pendulum in ways not easily accessible without computer technology and explore various algorithms for solving mechanics problems. Our computational physics is based on Mathematica with some C communicating with Mathematica, although nothing in this paper is dependent on that choice. We have nonetheless found this system, and particularly its graphics, to be a good one for use with undergraduates.

The time-course of morphological constraints: Evidence from eye-movements during reading

Lexical compounds in English are constrained in that the non-head noun can be an irregular but not a regular plural (e.g. mice eater vs. *rats eater), a contrast that has been argued to derive from a morphological constraint on modifiers inside compounds. In addition, bare nouns are preferred over plural forms inside compounds (e.g. mouse eater vs. mice eater), a contrast that has been ascribed to the semantics of compounds. Measuring eyemovements during reading, this study examined how morphological and semantic information become available over time during the processing of a compound. We found that the morphological constraint affected both early and late eye-movement measures, whereas the semantic constraint for singular non-heads only affected late measures of processing. These results indicate that morphological information becomes available earlier than semantic information during the processing of compounds.