Helmets improve estimations of depth and visual angle to safe targets

Egocentric distance estimation has been shown to depend on wearing safety gear, which promotes compensatory behavior, and on target type, which regulates fight-or-flight responses. We hypothesized that the two factors interact, possibly in asymmetric fashion, and set out to uncover the limits of this interaction in a perceptual task where individuals wearing helmets or baseball caps estimated egocentric distance to non-threatening and threatening animals depicted on cards (i.e., safe and unsafe targets). We found that, compared to participants wearing caps, participants wearing helmets overshoot distance estimations and were able to distinguish not only between targets situated at two depth levels as participants wearing caps could, but also between safe targets situated at wide and narrow visual angles. Our findings help define the interaction between safety devices and target type, thereby contributing to the debate between advocates of prevention models and those who maintain that these are offset by compensatory strategies.

Nocebo and pseudo-neglect: Paradoxical effects detected with eye-tracking

The knowledge about effects of placebos and nocebos on specific visual attention processes is still very limited. In the present eye-tracking study, it was analyzed if a nocebo (sham transcranial magnetic stimulation) is able to elicit left-sided attentional deficits (pseudo-neglect). Fifty-two healthy participants performed a search task on the computer, once with and once without the nocebo. Indicators of left-biased search behavior (e.g. fixation count, reaction times for left vs. right-sided target detection) and affective state (e.g., valence, arousal) were assessed. The sample was divided into two groups (nocebo responder, non-responder) based on the experienced effectiveness of the nocebo. The nocebo treatment was associated with a positive and calm affective state. Contrary to the verbal suggestion, the nocebo increased the number of fixations and the dwell time on the left side of the computer screen. Moreover, the nocebo decreased the detection time for targets on the left side. These paradoxical nocebo effects were restricted to nocebo responders. Possible implications of nocebo-related compensatory behaviors for neuropsychological therapy are discussed.

Effects of voluntary exercise on spontaneous physical activity and food consumption in mice: Results from an artificial selection experiment

We evaluated the effect of voluntary exercise on spontaneous physical activity (SPA) and food consumption in mice from 4 replicate lines bred for 57 generations for high voluntary wheel running (HR) and from 4 non-selected control (C) lines. Beginning at ~24 days of age, mice were housed in standard cages or in cages with attached wheels. Wheel activity and SPA were monitored in 1-min intervals. Data from the 8th week of the experiment were analyzed because mice were sexually mature and had plateaued in body mass, weekly wheel running distance, SPA, and food consumption. Body mass, length, and masses of the retroperitoneal fat pad, liver, and heart were recorded after the 13th week. SPA of both HR and C mice decreased with wheel access, due to reductions in both duration and average intensity of SPA. However, total activity duration (SPA+wheel running; min/day) was ~1/3 greater when mice were housed with wheels, and food consumption was significantly increased. Overall, food consumption in both HR and C mice was more strongly affected by wheel running than by SPA. Duration of wheel running had a stronger effect than average speed, but the opposite was true for SPA. With body mass as a covariate, chronic wheel access significantly reduced fat pad mass and increased heart mass in both HR and C mice. Given that both HR and C mice housed with wheels had increased food consumption, the energetic cost of wheel running was not fully compensated by concomitant reductions in SPA. The experiment demonstrates that both duration and intensity of both wheel running and SPA were significant predictors of food consumption. This sort of detailed analysis of the effects of different aspects of physical activity on food consumption has not previously been reported for a non-human animal, and it sets the stage for longitudinal examination of energy balance and its components in rodent models.