Judgments of approach speed for motorcycles across different lighting levels and the effect of an improved tri-headlight configuration.

The misperception of vehicle approach speed is a key contributory factor to road traffic crash involvement. Past research has indicated that individuals use the rate of visual looming to calculate the time to passage (TTP) of a vehicle, and that smaller vehicles loom to a lesser extent than larger vehicles. Despite a disproportionate number of fatal injuries occurring on the road after dark, and a higher than average number of accidents involving automobile drivers violating the right of way of a motorcyclist occurring in low light conditions, there has been very little consideration of the accuracy of TTP for smaller and larger vehicles under low levels of luminance. We investigated drivers' judgments of motorcycle and car approach speeds across a number of levels of luminance within a virtual city scene, as well as the effectiveness of a tri-headlight formation on motorcycle speed judgments. The accuracy of car approach speed judgments were not affected by changes in lighting conditions, but speed judgments for the solo headlight motorcycle became significantly less accurate as lighting reduced in the early night and night-time conditions. Incorporation of a tri-headlight formation onto the standard motorcycle frame resulted in improved accuracy of approach speed judgments, relative to the solo headlight motorcycle, as ambient light levels reduced. The practical implications of the findings are discussed in terms of road safety and motorcycle design.

Errors in judging the approach rate of motorcycles in nighttime conditions and the effect of an improved lighting configuration.

One of the key contributory factors for accident involvement is misjudgment of approach speed (Department for Transport, 2010). Past research has indicated that individuals can use the rate of visual looming in order to the judge time to passage (TTP) of approaching vehicles, and that smaller vehicles loom to a lesser extent than larger vehicles (e.g., Horswill et al., 2005). However, the judgment of TTP in nighttime conditions has received little attention. This paper explores drivers' abilities to make judgments of motorcycles and car approach speeds in nighttime driving conditions, when only the headlights are visible, as well as the effectiveness of a tri-headlight configuration on the accuracy of motorcycle speed judgments. Results showed that individuals were significantly more accurate at judging the speed of two car headlights compared with the standard solo headlight motorcycle. However, the inclusion of a tri-headlight formation on a standard motorcycle frame significantly improved these judgments. A further investigation demonstrated that tri-headlight configurations with separation between headlights on the horizontal and vertical axes are most effective for yielding accurate speed judgments. The implications of the results for road safety and motorcycle design are discussed.

The effect of learning condition on perceptual anticipation, awareness, and visual search.

The efficacy of explicit and implicit learning paradigms was examined during the very early stages of learning the perceptual-motor anticipation task of predicting ball direction from temporally occluded footage of soccer penalty kicks. In addition, the effect of instructional condition on point-of-gaze during learning was examined. A significant improvement in horizontal prediction accuracy was observed in the explicit learning group; however, similar improvement was evident in a placebo group who watched footage of soccer matches. Only the explicit learning intervention resulted in changes in eye movement behaviour and increased awareness of relevant postural cues. Results are discussed in terms of methodological and practical issues regarding the employment of implicit perceptual training interventions.

BTS1 encodes a geranylgeranyl diphosphate synthase in Saccharomyces cerevisiae.

Protein prenylation utilizes different types of isoprenoids groups, namely farnesyl and geranylgeranyl, to modify proteins. These lipophilic moieties attach to carboxyl-terminal cysteine residues to promote the association of soluble proteins to membranes. Most prenylated proteins are geranylgeranylated. Geranylgeranylation is catalyzed by two different prenyltransferases, the type I and type II geranylgeranyl transferases, both of which utilize geranylgeranyl diphosphate as a lipid donor. In the yeast Saccharomyces cerevisiae, the BET2 gene encodes the beta-subunit of the type II geranylgeranyl transferase. Mutations in this gene cause a defect in the geranylgeranylation of small GTP-binding proteins that mediate vesicular traffic. In an attempt to analyze those genes whose products may interact with Bet2, we isolated a suppressor of the bet2-1 mutant. This suppressor gene, called BTS1, encodes the yeast geranylgeranyl diphosphate synthase. BTS1 is not essential for the vegetative growth of cells; however, disrupting it impedes the geranylgeranylation of many cellular proteins and renders cells cold sensitive for growth. Our findings imply that BTS1 suppresses the bet2-1 mutant by increasing the intracellular pool of geranylgeranyl diphosphate.