Jean-Pierre Blondin

Positive and negative affective states in a performance-related setting: Testing the factorial structure of the panas across two samples of french-canadian participants.

The objective of the present study was to compare alternative factorial structures of the French-Canadian version of the Positive and Negative Affect Schedule (PANAS; Watson, Clark, & Tellegen, 1988) across samples of athletes at different stages of a sport competition. The first sample (N = 305) was used to assess, compare, and improve the measurement model of the PANAS. The second sample (N = 217) was used to cross-validate the model that provided the best fit with the calibration sample. Results of confirmatory factor analyses suggested that a modified three-factor model with cross-loadings provided a better fit to the data than either the hypothesized or the modified two-factor models. This model was partially replicated on the second sample. Results of a multiple-group confirmatory factor analysis have shown that the model was partially invariant across the two samples.

The stress of Stroop performance: physiological and emotional responses to color-word interference, task pacing, and pacing speed.

Heart rate, frequency of skin conductance responses, and self-reported anxiety were measured during performance of a computer version of the Stroop Color-Word Interference Test, and during a non-conflicting control task involving the color naming of color patches. Stroop and control stimuli were presented individually in order to vary task pacing. Subjects (N = 48) were divided into three groups assigned to self-paced, externally-paced, and fast externally-paced conditions. Performance data revealed that the relative proportion of speed and accuracy reductions which resulted from the Stroop interference varied according to task pacing and pacing speed. Stroop performance was accompanied by heightened HR levels which were sustained throughout the series. State-Anxiety scores increased after both tasks, but only among subjects who completed a large number of trials, i.e. subjects in the self-paced and fast externally-paced groups. Skin conductance responses only varied according to task order and time within series, irrespective of Stroop interference or task pacing. Overall, the results remained in accordance with an effort account of the relationship between attention and cardiac activity. They also provided indications on how the Stroop test may act as an efficient laboratory stressor.

Human perception of electric fields and ion currents associated with high-voltage DC transmission lines

The objective of this study was to assess the ability of humans to detect the presence of DC electric field and ion currents. An exposure chamber simulating conditions present in the vicinity of high-voltage DC (HVDC) lines was designed and built for this purpose. In these experiments, the facility was used to expose observers to DC electric fields up to 50 kV/m and ion current densities up to 120 nA/m2. Forty-eight volunteers (25 women and 23 men) between the ages of 18 and 57 years served as observers. Perception of DC fields was examined by using two psychophysical methods: an adaptive staircase procedure and a rating method derived from signal-detection theory. Subjects completed three different series of observations by using each of these methods; one was conducted without ion currents, and the other two involved various combinations of electric fields and ion currents. Overall, subjects were significantly more likely to detect DC fields as the intensity increased. Observers were able to detect the presence of DC fields alone, but only at high intensities; the average threshold was 45 kV/m. Except in the most sensitive individuals, ion current densities up to 60 nA/m2 did not significantly facilitate the detection of DC fields. However, higher ion current densities were associated with a substantial lowering of sensory thresholds in a large majority of observers. Data analysis also revealed large variations in perceptual thresholds among observers. Normative data indicating DC field and ion current intensities that can be detected by 50% of all observers are provided. In addition, for the most sensitive observers, several other detection proportions were derived from the distribution of individual detection capabilities. These data can form the basis for environmental guidelines relating to the design of HVDC lines.

Cardiovascular responses, performance, and mood in heart rate reactive individuals during a challenging cognitive task

Abstract Subjects ( n =24) were classified as either high or low in heart rate reactivity using a mental arithmetic task. They then performed computer versions of a challenging cognitive task, the Stroop Color-Word Interference Test. Subjects completed a congruent version of the Stroop task, and a more demanding incongruent version. Measures included heart rate (HR), systolic (SBP) and diastolic blood pressure (DBP), performance at the tasks in terms of speed and accuracy, and self reports of anxiety, depression and hostility. In comparison to the congruent task, the incongruent Stroop task elicited larger HR responses, as well as higher SBP and DBP levels among subjects of both reactivity groups. Furthermore, the incongruent task was associated with a cluster of negative emotional responses as reflected in the self-reports of heightened anxiety, depression, and hostility. Results indicated that the two reactivity groups differed in their cardiovascular and behavioral responses to the tasks. Although there was no difference between groups during the incongruent Stroop task, only the highly reactive subjects showed HR increases during the easy, congruent task. These subjects also showed more labile SBP fluctuations across conditions, whereas variations in DBP were not affected by HR reactivity. Performance results revealed that highly reactive subjects coped with the incongruent task by adopting a slower pace than low HR reactive subjects. There were no significant differences between groups for trait and state measures of anxiety, depression and hostility.