John JB Allen

Abstract:

Emotion is an important aspect in the interaction between humans. There is a great interest for detecting emotions automatically. Current approaches for emotion detection using EEG are not practical for real-life situations because researchers ask participants to reduce any motion and facial muscle movement, reject noisy EEG data and rely on large number of electrodes. In this paper, we propose an approach that analyses highly contaminated brain signals. We then extract relevant features for the emotion detection task based on neuroscience findings. We reached an average accuracy of 51%, 53%, 58% and 61% for joy, anger, fear and sadness, respectively. We are also applying our approach on fewer number of electrodes that ranges from 4 to 25 electrodes and we reached an average classification accuracy of 33% for joy emotion, 38% for anger, 33% for fear and 37.5% for sadness using 4 or 6 electrodes only. Copyright © 2013 Inderscience Enterprises Ltd.

PMID: 15032992;Abstract:

Although resting frontal electroencephalographic (EEG) alpha asymmetry has been shown to be a stable measure over time in nonclinical populations, its reliability and stability in clinically depressed individuals has not been fully investigated. The internal consistency and test-retest stability of resting EEG alpha (8-13 Hz) asymmetry were examined in 30 women diagnosed with major depression at 4-week intervals for 8 or 16 weeks. Asymmetry scores generally displayed good internal consistency and exhibited modest stability over the 8- and 16-week assessment intervals. Changes in asymmetry scores over this interval were not significantly related to changes in clinical state. These findings suggest that resting EEG alpha asymmetry can be reliably assessed in clinically depressed populations. Furthermore, intraclass correlation stability estimates suggest that although some traitlike aspects of alpha asymmetry exist in depressed individuals, there is also evidence of changes in asymmetry across assessment occasions that are not closely linked to changes in depressive severity.

PMID: 19015117;PMCID: PMC2566773;Abstract:

Psychological disengagement allows stigmatized individuals to cope with negative outcomes in stereotype-relevant domains, but its role in online performance monitoring and adjustment is unknown. This study examined how two forms of disengagement (devaluing and discounting) predict performance monitoring at an early (motivational) and later (interpretational) stage of error processing. Among minority college students, event-related brain activity was measured in response to errors on tasks described neutrally or as diagnostic of intelligence. Results found dissociable effects for error-related negativity (ERN) and later positivity (Pe). When the task was linked to intelligence, valuing academics predicted larger ERNs. Unexpectedly, discounting tendencies predicted smaller Pes when the task was described neutrally, a relationship that was attenuated and somewhat reversed when explicitly linking the task to intelligence. In the diagnostic condition, valuing also predicted more efficient behavioral responses to errors, whereas discounting predicted more negative task construals. Results suggest that among stereotype threatened minority students, devaluing has implications for early stage motivational processes involved in monitoring and responding to errors, whereas discounting may have implications for later construal processes. © The Author (2008). Published by Oxford University Press.

PMID: 18801582;PMCID: PMC2688527;Abstract:

Background: Tryptophan depletion (TD) reduces brain serotonin and may induce acute depressive symptomatology, especially among those with a history of Major Depression. Depressive response to TD among euthymic patients with a history of depression also predicts future depression. Better prediction might result by assessing a putative endophenotype for depressive risk, frontal electroencephalographic (EEG) asymmetry, in the context of TD. Method: Nine euthymic history-positive participants and nine controls were administered TD. Symptomatic and EEG frontal asymmetry data were collected for 6 h following TD, and clinical status was followed for the next 12 months. Results: The magnitude of TD-induced change in frontal EEG asymmetry significantly predicted the development of depression during the ensuing six to twelve months, and with greater sensitivity than symptomatic response. Limitations: The results are tempered by the small sample size. Conclusions: Despite the limited sample size, these preliminary results suggest that TD-induced changes in frontal EEG asymmetry may provide a more sensitive indicator of risk for imminent depression than symptomatic response to TD. © 2008 Elsevier B.V. All rights reserved.

Abstract:

Affective models of the mere exposure effect propose that repeated exposure to a stimulus increases the positive affect or reduces the negative affect toward the stimulus, whereas recent cognitive models propose that affect is not involved in the mere exposure effect. To test these competing predictions, participants repeatedly viewed photographs of women's faces and then viewed these women again (familiar) and novel women (unfamiliar) while facial muscle region activity and brain activity were recorded. Familiar stimuli were rated as more likable and they evoked more zygomatic (cheek) muscle region activity than unfamiliar stimuli. Interactions with individual differences occurred. Persons reporting less positive affect and persons reporting more negative affect at baseline evidenced more zygomatic activity to the familiar than to the unfamiliar. Persons with relatively less left frontal cortical activation at baseline evidenced a tendency toward a greater mere exposure effect. These results suggest that repeatedly exposing persons to nonreinforced stimuli increases their positive affective reactions to those stimuli.