Measuring working memory load effects on electrophysiological markers of attention orienting during a simulated drive

Intersection accidents result in a significant proportion of road fatalities, and attention allocation likely plays a role. Attention allocation may depend on (limited) working memory (WM) capacity. Driving is often combined with tasks increasing WM load, consequently impairing attention orienting. This study (n = 22) investigated WM load effects on event-related potentials (ERPs) related to attention orienting. A simulated driving environment allowed continuous lane-keeping measurement. Participants were asked to orient attention covertly towards the side indicated by an arrow, and to respond only to moving cars appearing on the attended side by pressing a button. WM load was manipulated using a concurrent memory task. ERPs showed typical attentional modulation (cue: contralateral negativity, LDAP; car: N1, P1, SN and P3) under low and high load conditions. With increased WM load, lane-keeping performance improved, while dual task performance degraded (memory task: increased error rate; orienting task: increased false alarms, smaller P3). Practitioner Summary: Intersection driver-support systems aim to improve traffic safety and flow. However, in-vehicle systems induce WM load, increasing the tendency to yield. Traffic flow reduces if drivers stop at inappropriate times, reducing the effectiveness of systems. Consequently, driver-support systems could include WM load measurement during driving in the development phase

Recording of swallowing events using electromyography as a non-invasive measurement of salivation

The present study examined whether the measurement of swallowing activity by electromyography (EMG) provides a sensitive and valid method for the assessment of the amount of saliva secreted. Thirteen subjects tasted lemon juice and water, and smelled lasagna and hay, while the amount of saliva, measured with the aid of cotton dental rolls, was compared with the number of peaks in the EMG activity of the musculus digastricus. Swallowing indeed diVerentiated between the stimuli and the correlation between the number of swallows and the amount of saliva was signi®cant. The present data suggest that monitoring the swallowing movement using EMG might be a sensitive, valid and reliable method for the measurement of salivary ¯ow. The use is recommended for the measurement of salivation when a simple and non-invasive method is needed. Ó 1999 Academic Pres

Effects of task variables on measures of the mean onset latency of LRP depend on the scoring method

The lateralized readiness potential (LRP) can be used to index the start of response activation. The onset of the average LRP can be computed as the latency at which the component starts to deviate significantly from zero or as the latency at which a certain proportion of its maximum amplitude is attained. The properties of both measures as estimates of the mean onset latency of the LRP were examined. Experiment 1 was a simulation study in which the mean onset latencies were known. Results indicated different types of bias for the two measures and greater reliability for a proportional measure. In Experiment 2, the sensitivity to bias, consistency, and linearity of both measures were evaluated in a set of empirical data. By all three criteria, a proportional onset measure was superior. It is recommended that the choice of the measure should depend on the hypothesis to be tested, so that conclusions are based on the more conservative test

Effects of task complexity in young and old adults: Reaction time and P300 latency are not always dissociated

Twelve young and 11 elderly men (mean ages 21.1 and 70.1) performed a choice-reaction time (RT) task in which stimulus degradation and stimulus-response (S-R) compatibility were manipulated. The extant literature has suggested that the effects of age on RT are usually augmented (multiplicative) in more difficult task conditions, but also that the effects of age on the latency of the P300 component of the event-related brain potential (ERP) are constant (additive). The results indicated that the effects of age on RT were enhanced in more difficult conditions, whether the difficulty consisted of stimulus degradation or S-R incompatibility. However, the effects of age on P300 latency were enlarged as the stimuli were degraded, but not if the S-R mapping was incompatible. Thus, it appears that task content determines if effects of age on P300 latency are additive or multiplicative. A simple model is proposed that produces the obtained pattern of effects

The Temporal Selectivity of Additive Factor Effects on the Reaction Process Revealed in Erp Component Latencies

An experiment was conducted to relate individual components of the event-related brain potential to specific stages of information processing in a two-choice reaction time (RT) task in a group of undergraduate students. Specifically, the latency of the P300 component and the lateralized readiness potential (LRP) were studied as a function of variations in stimulus degradation and response complexity. It was hypothesized that degrading the stimulus would delay the P300 and LRP to the same extent as RT, and that increasing response complexity would affect RT but not P300 latency. The extant literature did not permit any hypothesis regarding the effect of response complexity on LRP latency. The two task variables were found to have additive effects on RT. As predicted, variations in stimulus degradation influenced the latencies of both components, whereas alterations in response complexity had no effect on P300 latency. A significant new finding was that the onset latency of the LRP remained unchanged across levels of response complexity. The overall pattern of results supports the notion of temporal selectivity of stage manipulations that is derived from discrete stage models of human information processing. Furthermore, these results refine the functional interpretation of the LRP by indicating that within the conceptual framework of a stage model the processes this component indexes succeed the start of response choice but precede the start of motor programming