Indicators Of Mental Effort Research Articles

Comparing the Difficulty of Tasks Using Eye Tracking Combined with Subjective and Behavioural Criteria

In this article, we attempted to examine the issue of the existence of differences in eye move-ment of school-age students as they solve tasks of different difficulty levels in the sciences and natural sciences (computer science, mathematics, physics, biology). Categories of the task’s difficulty level were established on the basis of two types of criteria: subjective (an evaluation made by the subjects) and behavioural (connected to the correctness of their solution). The relationships of these criteria with the visual activity parameters, which were considered to be indicators of mental effort, were identified. An analysis of the data obtained enabled the observation of discrepancies in categorizing difficulties of the tasks on the basis of subjective and behavioural criteria. A significant and strong correlation was noticed between task difficulty level, determined by the percentage of correct answers, and the fixation parameters, although such a relationship with the blink parameters was not found. There was no correlation of the activity of the eye movement parameters, considered to be mental effort indicators, with a student’s opinion about the task’s difficulty level. On the basis of the investigations made, it can be stated that the fixation duration average can be taken as an index of the difficulty level of the task being solved.

Short-term cardiovascular measures for driver support: Increasing sensitivity for detecting changes in mental workload

With on-going increases in traffic density and the availability of more and more in-vehicle technology, driver overload is a growing concern. To reduce the burden of workload on the driver, it is essential that support systems that become available are able to use estimations of drivers' workload. In this paper a short-term cardiovascular approach to assess drivers' mental workload is described using data collected in a driving simulator study. The effects of short lasting increases in task demand (40s) on heart rate and blood pressure and derived variability measures are applied as indicators of mental effort. Fifteen drivers participated in 6 sessions of 1.5h in a driving simulator study. Two traffic density levels (7.5minute segments) were compared in which short-segments (40s) of fog were used to induce additional workload demands. Higher traffic density was reflected in increased systolic blood pressure and decreased blood pressure variability. Heart rate variability and blood pressure variability measures decreased during driving in fog in the low traffic condition, indicating increased effort investment during fog in this condition. The results show that the described short-term measures can be applied to give an indication of cardiovascular reactivity as a function workload.

Cognitive effects of noise reduction strategies

Noise reduction algorithms that attempt to improve speech intelligibility in noise have been used in hearing aids for decades. Yet, the surprising result has been that they are not effective in improving the speech reception threshold (SRT). One explanation is that the artificial processing is redundant, providing the same information as that extracted by the listener’s own auditory system. Our working hypothesis is that natural processing is effective only if there are sufficient cognitive resources to support it and that a reduction in those resources may increase the functional value of the computational algorithm. In the present experiments, subjects performed in a dual-task paradigm in which they listened to and repeated sentences presented in a noisy background while doing a competing visual task, such as a simple driving game. Using driving performance as an indicator of mental effort, we evaluate the effects of different noise reduction algorithms on speech reception. The logic is that, while there will be a loss in performance due to doing two difficult tasks at once, this loss will be smaller when auditory sentences are processed by noise reduction.