Cold-Blooded Attention: Finger Temperature Predicts Attentional Performance

EDA, PPG and Skin Temperature as Predictive Signals for Mental Failure by a Statistical Analysis on Stress and Mental Workload

Objective: The growth of autonomous systems interacting with humans leads to assessing operators' stress and mental workload (MWL), especially in safety-critical situations. Therefore, a system providing information about the psychophysiological workers' condition is fundamental and still missing. This paper aims to study the statistical relationship between the variation of Photoplethysmogram signal (PPG), Electrodermal Activity (EDA), and skin temperature with respect to stress and MWL levels, assessed through an ad-hoc developed subjective questionnaire. Results: 43 features were calculated from these signals during the execution of two cognitive tests and processed through a statistical analysis based on Kruskal-Wallis and Mann-Whitney U tests. This analysis proved that about 50% of them offered statistical evidence in differentiating relaxed and altered emotional conditions. Moreover, fifteen features were found to provide sufficient information to detect at the same time stress and MWL. Conclusions: These results demonstrate the feasibility of this approach and push to continue this research about the relationship between physiological signals and the variation of stress and MWL by enhancing the population and considering more biosignals.

The ability of peripheral neurophysiological biomarkers to predict future psychological conditions among geriatric populations

OBJECTIVE

Though the association between peripheral neurophysiological biomarkers and psychological conditions is widely discussed, there is still limited evidence about the ability of peripheral biomarkers to predict psychological outcomes, especially among geriatric populations.

METHODS

The study is designed as a prospective cohort study. We collected information from participants aged over 55 years. The participants were evaluated at the start of the study (T0) and 6-9 months later (T1). Information about demographic profiles, peripheral neurophysiological biomarker recordings (including heart rate variability, finger temperature, skin conductance, and electromyogram), and psychological measurements (including Brief Symptom Rating Scale-5, Chinese Happiness Inventory, and Short Portable Mental Status Questionnaire) were collected at T0. At T1, participants reported self-rated questionnaires for psychological outcomes (Patient Health Questionnaire-15, health anxiety questionnaire, Beck Depression Inventory-II, and Beck Anxiety Inventory) and were evaluated with Mini-Mental State Examination by the staff. The association between the peripheral biomarkers and psychological outcomes was evaluated via multiple regression models.

RESULTS

A total of 385 participants were included in the study and the average age was 74.49 ± 7.34 years. Both stepwise multiple linear and logistic models showed a significant association between decreased skin conductance and increased/presence of depression at T1. The receiver operating characteristic (ROC) curve analysis of skin conductance for depression was fair (area under curve = 0.812).

CONCLUSIONS

The ability of skin conductance to predict depression among geriatric populations may facilitate the detection of geriatric depression and future research on the pathophysiology.

Your lies don't leave me cold: Assessing direct, indirect and physiological measures of lie detection

People tend to be bad at detecting lies: When explicitly asked to infer whether others tell a lie or the truth, people often do not perform better than chance. However, increasing evidence suggests that implicit lie detection measures and potentially physiological measures may mirror observers' telling apart lies from truths after all. Implicit and physiological responses are argued to respond to lies as a threatening stimulus associated with a threat response. Subsequently, people who tell a lie should thus be liked and trusted less than those who tell the truth (indirect lie detection measures). In terms of physiology, a threat response should be associated with narrowing blood vessels (vasoconstriction), which should reduce peripheral skin blood flow. Consequently, we expected lower finger temperatures when confronted with a lie compared to the truth. We test lie detection using explicit and indirect measures, as well as using infrared thermal imaging as a physiological measure of lie detection. Participants (N = 95) observed videos of people telling lies or the truth about their social relationships, during which participants' fingertip temperature was recorded. Results suggested that the accuracy of explicit categorizations remained at chance level. Judgments of story-tellers' likability and trustworthiness (indirect measures of lie detection) showed no evidence that observers could tell apart liars and truthtellers: Those believed to be truthtellers were liked and trusted significantly more than those believed to be liars, even when this belief was mistaken. Physiological lie detection measured using thermal imaging also failed: Observers' fingertip temperatures did not significantly differ between lies and true stories. If at all, the temperature effects pointed in the opposite direction of the lies-as-threat expectations: Fingertip temperatures increased somewhat while confronted with lies compared to true stories. Results support the impression that people are bad at detecting lies, and cast doubt on whether fingertip temperature responses could be used as lie detection mechanisms.

Finger Temperature: A Psychophysiological Assessment of the Attentional State

Attention is a key cognitive phenomenon that is studied to understand cognitive disorders or even to estimate workloads to prevent accidents. Usually, it is studied using brain activity, even though it has many psychophysiological correlates. In the present study, we aim to evaluate if finger temperature, as a surrogate of peripheral vasoconstriction, can be used to obtain similar and complementary information to electroencephalography (EEG) brain activity measurements. To conduct this, 34 participants were recruited and submitted to performing four tasks-one as a baseline, and three attentional tasks. These three attentional tasks measured sustained attention, resilience to distractors, and attentional resources. During the tasks, the room, forehead, tympanic, and finger temperatures were measured. Furthermore, we included a 32-channel EEG recording. Our results showed a strong monotonic association between the finger temperature and the Alpha and Beta EEG spectral bands. When predicting attentional performance, the finger temperature was complementary to the EEG spectral measurements, through the prediction of aspects of attentional performance that had not been assessed by spectral EEG activity, or through the improvement of the model's fit. We also found that during the baseline task (non-goal-oriented task), the spectral EEG activity has an inverted correlation, as compared to a goal-oriented task. Our current results suggest that the psychophysiological assessment of attention is complementary to classic EEG approach, while also having the advantage of easy implementation of analysis tools in environments of reducing control (workplaces, student classrooms).