Reliability of electrodermal habituation measures under two conditions of stimulus intensity

The present study investigated test-retest reliability of habituation of the evoked skin conductance response. Subjects received 20 presentations of a 1000-Hz, 3-sec tone at the same time of day on two separate occasions, separated by an interval of 97–160 days. Thirteen subjects received stimuli of 90 dB, while for 24 subjects, stimulus intensity was 70 dB. Interstimulus interval was 21 sec for both groups. Both absolute rate of habituation and trials to criterion displayed moderate reliability, and the relationships between habituation measures and other aspects of electrodermal activity were in agreement with previous findings.     

Extraversion and the orienting reaction habituation rate to visual stimuli

Eysenck's (1967) proposal that introversion is characterized by increased levels of activity in the cortico-reticular loop was treated in a series of experiments which compared high, middle, and low extraversion groups on the basis of OR habituation rate to visual stimulation. Generally, introverts were observed to have longer OR habituation rates to chromatic and word stimulation than extraverts as evidenced by cardiac, electrodermal, and vasomotor indices of habituation rate, a result which endorses Eysenck's hypothesis. Results are also discussed from the standpoint of individual differences in autonomic response.     

How brain arousal systems determine different temperament types and the major dimensions of personality

Theory and research is described which led to the hypothesis that the choleric (E+N+) and melancholic (E−N+) temperaments are determined by differences in thalamocortical inhibition of brain-stem processes. An opportunity to test this hypothesis was provided by the recent discovery of 4, 7, and 10 Hz response waves confounded in EEG averaged evoked potentials [Robinson, D. L. (1999b). The technical, neurological, and psychological significance of ‘alpha’ ‘theta’ and ‘delta’ waves confounded in EEG evoked potentials: 1. A study of peak latencies. Electroencephalography and Clinical Neurophysiology, 110, 1427–1434; (2000). The technical neurological, and psychological significance of ‘alpha’, ‘delta’, and ‘theta’ waves confounded in EEG evoked potentials: A study of peak amplitudes. Personality and Individual Differences, 28, 673–693]. These responses are attributed to the brain-stem, limbic, and thalamocortical arousal systems, respectively, and in the cited reports principal components analysis of data obtained from 93 participants confirmed the existence of predicted excitatory and inhibitory relationships. ANOVA was used in the present study to test the further prediction that there should be strong inhibition of the 4 Hz system by the 10 Hz system in melancholics (E−N+) and weak inhibition of the 4 Hz system in cholerics (E+N+), with median inhibition predicted for the other temperament types. There was a large and statistically significant difference between the mean scores on the PCA inhibition factor obtained for the temperament groups, with temperament defined in terms of high and low EPQ extraversion (E) and neuroticism (N) scores. The significance of these results is discussed with reference to fundamental questions raised by Pavlov's pioneering research but left unanswered for the best part of a century. Implications for the future conduct of personality research are also considered.     

Electrodermal responses to movie stressors: Nicotine × extraversion interactions

Support was found for Eysenck's hypothesis that the effects of smoking sized doses of nicotine on cortical and electrodermal activity are functions of extraversion and the degree of externally-induced arousal. Responses to scenes that elicited moderate electrodermal and emotional responses followed the predicted extraversion ☆ nicotine interaction for electrodermal measures, but not for self-reported emotions, heart rate or electromyographic measures. The failure of the Ss to demonstrate an extraversion ☆ nicotine interaction when high-intensity stimuli were used (Gilbert and Hagen, 1980) is also interpreted as consistent with Eysenck's hypothesis.     

A Psychogenic Study of Dark-Adaptation

Skin conductance responses (SCRs), heart rate (HR), and respiration were recorded in various rest, cold pressor (CP), and CP recovery phases in 20 former drug users (DG) and 20 control Ss (CG), matched on sex and age in a repeated measures design. With regard to the abused drugs (barbiturates and narcotic analgesics), the hypothesis was tested that autonomic responses are decreased after long-term use of barbiturates and narcotic analgesics. The results partially supported that hypothesis: (a) SCRs, HR change, and HR deceleration were significantly lower in DG compared to control Ss; (b) HR baseline, respiration rate, and amplitude, however, tended to be increased in DG in the rest and CP phases. A second hypothesis, addressed to different habituation rates of SCRs and HR in both groups, was confirmed for SCRs and partly for HR, indicating that the habituation rates of SCRs, HR change, and HR deceleration were greater in DG than in CG. A third question concerned the consistency of SCR and HR results in both sessions. A trend for consistent results was found as the direction of the group differences was the same in sessions 1 and 2. The CP results were compared with similar findings in the same Ss during visual and auditory stimulation.     

An adjusted measure of achievement motivation for males and females and effects of future orientation on level of performance

An adjusted measure of achievement motivation was devised with the combined use of the Mehrabian Achievement Scale (Educational and Psychological Measurement, 1968, 28, 493–502) and the Mandler and Sarason (Journal of Abnormal and Social Psychology, 1952, 47, 166–173) Test Anxiety Questionnaire. Contingent instructions, in which Ss were told success on a test was necessary to qualify for opportunities to succeed on subsequent tests, were contrasted to performance in equivalent noncontingent situations and relative to adjusted achievement motivation for both male and female subjects. In noncontingent situations Ss were told performance on any one test did not affect their opportunity to take subsequent tests. Support was obtained for the use of the above mentioned scales as a predictor of performance for both sexes but not for the Mehrabian by itself. Both male and female Ss high in achievement motivation consistently scored significantly higher than Ss low in achievement motivation in all conditions. The expected interactions between treatments and motive groups were not found but t tests between extreme motive groups within conditions revealed significant differences in the expected directions. These results do not provide statistically reliable support to the elaborated theory of achievement motivation.     

Olfaction as a model system for the neurobiology of mammalian short-term habituation

Olfaction represents an ideal model system for the study of mammalian habituation given that it is an anatomically relatively simple system with strong reciprocal connections to the limbic system, driving both reflexive and non-reflexive (motivated) behaviors that are easily quantifiable. Data are reviewed here demonstrating short-term habituation of the odor-evoked heart-rate orienting reflex described according to the criteria for habituation outlined by Thompson and Spencer [Thompson, R. F., & Spencer, W. A. (1966). Habituation: A model phenomenon for the study of neuronal substrates of behavior. Psychological Reviews, 73(1), 16–43]. A necessary and sufficient mechanism of short-term habituation is then described, which involves a metabotropic glutamate receptor mediated depression of afferent input to the piriform (primary olfactory) cortex. Finally, evidence for, and a mechanisms of, dishabituation of the orienting reflex and cortical adaptation are described.     

Extraversion and neuroticism: Investigation of resting electrodermal activity

In 1967 Eysenck published his biological account of extraversion and neuroticism. In the same year Claridge identified several problems with this theory. More recently Robinson has detailed a promising modification to Eysenck's theory which addresses many of the issues raised by Claridge. Drawing on Robinson's theory it was hypothesised that differences in resting electrodermal activity (EDA) would contrast extraverted‐neurotics (low arousal) and introverted‐neurotics (high arousal). The Eysenck Personality Questionnaire (EPQ) was used to identify four extreme groups of female participants: extraverted‐stable (n = 16), extraverted‐neurotic (n = 15), introverted‐stable (n = 8) and introverted‐neurotic (n = 16). EDA measures of skin conductance level (SCL) and non‐specific skin conductance response (NS‐SCR) were collected during two rest periods. Planned contrasts between the extraverted‐neurotic and introverted‐neurotic groups provided support for Robinson's theory on SCL but not NS‐SCR. It was argued that the results for NS‐SCR frequency could be accommodated by Robinson's theory if NS‐SCR was conceptualised as a measure of cortical reactivity to unspecified stimuli rather than as a measure of tonic arousal.     

The basolateral amygdala modulates specific sensory memory representations in the cerebral cortex

Stress hormones released by an experience can modulate memory strength via the basolateral amygdala, which in turn acts on sites of memory storage such as the cerebral cortex [McGaugh, J. L. (2004). The amygdala modulates the consolidation of memories of emotionally arousing experiences. Annual Review of Neuroscience, 27, 1–28]. Stimuli that acquire behavioral importance gain increased representation in the cortex. For example, learning shifts the tuning of neurons in the primary auditory cortex (A1) to the frequency of a conditioned stimulus (CS), and the greater the level of CS importance, the larger the area of representational gain [Weinberger, N. M. (2007). Associative representational plasticity in the auditory cortex: A synthesis of two disciplines. Learning & Memory, 14(1–2), 1–16]. The two lines of research suggest that BLA strengthening of memory might be accomplished in part by increasing the representation of an environmental stimulus. The present study investigated whether stimulation of the BLA can affect cortical memory representations. In male Sprague–Dawley rats studied under urethane general anesthesia, frequency receptive fields were obtained from A1 before and up to 75 min after the pairing of a tone with BLA stimulation (BLAstm: 100 trials, 400 ms, 100 Hz, 400 μA [±16.54]). Tone started before and continued after BLAstm. Group BLA/1.0 (n = 16) had a 1 s CS–BLAstm interval while Group BLA/1.6 (n = 5) has a 1.6 s interval. The BLA/1.0 group did develop specific tuning shifts toward and to the CS, which could change frequency tuning by as much as two octaves. Moreover, its shifts increased over time and were enduring, lasting 75 min. However, group BLA/1.6 did not develop tuning shifts, indicating that precise CS–BLAstm timing is important in the anesthetized animal. Further, training in the BLA/1.0 paradigm but stimulating outside of the BLA did not produce tuning shifts. These findings demonstrate that the BLA is capable of exerting highly specific, enduring, learning-related modifications of stimulus representation in the cerebral cortex. These findings suggest that the ability of the BLA to alter specific cortical representations may underlie, at least in part, the modulatory influence of BLA activity on strengthening long-term memory.     

Nonverbal cues to sex-role attitudes

This study explored the relationship between self-reported attitudes toward “masculinity-femininity” and nonverbal behavior as judged by peers. Subjects (Ss) were preselected using an Mf questionnaire into: high-“feminine” males (N = 16) and females (N = 15) and low-feminine males (N = 16) and females (N = 15). The 62 Ss were videotaped in a 5-min standardized interview. Peer-age judges (Js) then viewed the videotapes without sound and asked to check which of the 170 adjectives describe Ss. Some Js were asked to rate average college male and female. A large number of adjectives discriminated the sexes (91 out of 170). Women were more often seen as warm, affable, oversocialized, emotional, and unstable. Men were seen as forceful, dominant, and detached. Sixty-two adjectives discriminated high- and low-feminine women. Feminine women were seen as warm, affable, oversocialized, and submissive, while low-feminine women were seen as dominant. High-feminine men were described as impulsive, dominant, and socially uneasy, while low-feminine men were seen as oversocialized and conventional.     

Brain oscillations during semantic evaluation of speech

Changes in oscillatory brain activity have been related to perceptual and cognitive processes such as selective attention and memory matching. Here we examined brain oscillations, measured with electroencephalography (EEG), during a semantic speech processing task that required both lexically mediated memory matching and selective attention. Participants listened to nouns spoken in male and female voices, and detected an animate target (p = 20%) in a train of inanimate standards or vice versa. For a control task, subjects listened to the same words and detected a target male voice in standards of a female voice or vice versa. The standard trials of the semantic task showed enhanced upper beta (25–30 Hz) and gamma band (GBA, 30–60 Hz) activity compared to the voice task. Upper beta and GBA enhancement was accompanied by a suppression of alpha (8–12 Hz) and lower to mid beta (13–20 Hz) activity mainly localized to posterior electrodes. Enhancement of phase-locked theta activity peaking near 275 ms also occurred over the midline electrodes. Theta, upper beta, and gamma band enhancement may reflect lexically mediated template matching in auditory memory, whereas the alpha and beta suppression likely indicate increased attentional processes and memory demands.     

Habituation in Aplysia: The Cheshire Cat of neurobiology

The marine snail, Aplysia californica, is a valuable model system for cell biological studies of learning and memory. Aplysia exhibits a reflexive withdrawal of its gill and siphon in response to weak or moderate tactile stimulation of its skin. Repeated tactile stimulation causes this defensive withdrawal reflex to habituate. Both short-term habituation, lasting <30 min, and long-term habituation, which can last >24 h, have been reported in Aplysia. Habituation of the withdrawal reflex correlates with, and is in part due to, depression of transmission at the monosynaptic connection between mechanoreceptive sensory neurons and motor neurons within the abdominal ganglion. Habituation-related short-term depression of the sensorimotor synapse appears to be due exclusively to presynaptic changes. However, changes within the sensory neuron, by themselves, do not account for more persistent depression of the sensorimotor synapse. Recent behavioral work suggests that long-term habituation in Aplysia critically involves postsynaptic processes, specifically, activation of AMPA- and NMDA-type receptors. In addition, long-term habituation requires activity of protein phosphatases, including protein phosphatases 1, 2A, and 2B, as well as activity of voltage-dependent Ca²⁺ channels. Cellular work has succeeded in demonstrating long-term, homosynaptic depression (LTD) of the sensorimotor synapse in dissociated cell culture and, more recently, LTD of the glutamate response of isolated motor neurons in culture (“hemisynaptic” LTD). These in vitro forms of LTD have mechanistic parallels to long-term habituation. In particular, homosynaptic LTD of the sensorimotor synapse requires elevated intracellular Ca²⁺ within the motor neuron, and hemisynaptic LTD requires activity of AMPA- and NMDA-type receptors. In addition, activation of group I and II metabotropic glutamate receptors (mGluRs) can induce hemisynaptic LTD. The demonstration of LTD in vitro opens up a promising new avenue for attempts to relate long-term habituation to cellular changes within the nervous system of Aplysia.     

Attentional focus moderates habituation–language relationships: slow habituation may be a good thing

An interesting paradox in the developmental literature has emerged in which fast‐habituating babies tend to be temperamentally difficult and fast language learners, even though temperamentally difficult babies tend to be slow language learners. The purpose of the present investigation was to examine whether the paradoxical relationships among habituation, temperamental difficulty, and language acquisition could be mediated partly or wholly by infant attentional focus, because the latter also tends to correlate with temperamental difficulty and vocabulary size. Forty mother–infant dyads were followed from child age 5–20‐months. Results replicated those of Tamis‐LeMonda and Bornstein (Child Develop 1989, 60, 738–751): measures of visual habituation at 5 months were related to 13‐month vocabulary. However, relationships between 5‐month habituation and 20‐month vocabulary were moderated by temperamental attentional focus. For children low in attentional focus, 5‐month habituation was related negatively to 20‐month productive vocabulary; whereas for children high in attentional focus, early habituation was positively related to later vocabulary. Results are consistent with a model of habituation in which volitional attentional focus overrides basic attentional mechanisms that occur during habituation. Copyright © 2008 John Wiley & Sons, Ltd.     

Extraversion and the effects of frequency and intensity on the auditory brainstem evoked response

Extraversion was positively correlated with the latency of wave I of the auditory brainstem evoked response (BER) at 75, 80 and 85 dB of intensity. Extraverts also tended to display longer latency for wave V than introverts to high frequency, 80-dB tone bursts and to click stimuli at intensity levels which ranged from 55 to 85 dB (SPL). These results are consistent with reports of greater auditory sensitivity (d') and enhanced amplitude of the late (N₁–P₂) cortical evoked response for introverts. The absence of differences in interpeak latency, or central transmission time. center the effects on wave I which is thought to be generated by the cochlear nerve. The present findings may require the elaboration of the neurophysiological bases of extraversion, which presently focuses on differences in cortico-reticular arousal systems, to accomodate individual differences in axonal or synaptic transmission.     

Effects of a coactor's prediction on latencies to predict and indentify stimuli

On each of 300 trials E's confederate (C) verbalized which of two stimuli would occur; then S made a prediction. Following each presentation, S and C pulled a trigger to identify the stimulus. Two latencies were measured: the interval between C's and S's prediction (prediction time), and the interval between stimulus presentation and S's identification response (choice RT). Prediction times were significantly shorter when S's prediction agreed rather than disagreed with C's prediction, when S's preceding prediction was correct rather than incorrect, and when S was female rather than male. Choice RT was influenced by distributions of C's stimulus predictions and C's prediction outcomes in directions supporting an expectancy model.     

Neurogenetic approaches to habituation and dishabituation in Drosophila

We review work in the major model systems for habituation in Drosophila melanogaster, encompassing several sensory modalities and behavioral contexts: visual (giant fiber escape response, landing response); chemical (proboscis extension reflex, olfactory jump response, locomotory startle response, odor-induced leg response, experience-dependent courtship modification); electric (shock avoidance); and mechanical (leg resistance reflex, cleaning reflex). Each model system shows several of Thompson and Spencer’s [Thompson, R. F., & Spencer, W. A. (1966). Habituation: A model phenomenon for the study of neuronal substrates of behavior. Psychological Review, 73, 16–43] parametric criteria for habituation: spontaneous recovery and dishabituation have been described in almost all of them and dependence of habituation upon stimulus frequency and stimulus intensity in the majority. Stimulus generalization (and conversely, the delineation of stimulus specificity) has given insights into the localization of habituation or the neural architecture underlying sensory processing.The strength of Drosophila for studying habituation is the range of genetic approaches available. Mutations have been used to modify specific neuroanatomical structures, ion channels, elements of synaptic transmission, and second-messenger pathways. rutabaga and dunce, genes of the cAMP signal pathway that have been studied most often in the reviewed experiments, have also been implicated in synaptic plasticity and associative conditioning in Drosophila and other species including mammals. The use of the Gal4/UAS system for targeting gene expression has enabled genetic perturbation of defined sets of neurons. One clear lesson is that a gene may affect habituation differently in different behaviors, depending on the expression, processing, and localization of the gene product in specific circuits. Mutations of specific genes not only provide links between physiology and behavior in the same circuit, but also reveal common mechanisms in different paradigms of behavioral plasticity. The rich repertoire of models for habituation in the fly is an asset for combining a genetic approach with behavioral, anatomical and physiological methods with the promise of a more complete understanding.     

Extraversion and neuroticism in orienting reflex dishabituation

The present study examined the effects of extraversion (E) and neuroticism (N) as individual difference dimensions and of stimulus intensity on electrodermal orienting response habituation, test response, and dishabituation. Subjects were 162 college students selected from a screening sample of 860 as representing extreme groups of high, medium, and low E crossing with high, medium, and low N. Subjects in all nine resulting groups were habituated to criterion on auditory stimuli of 60, 80, and 100 db. A novel (test) stimulus and a dishabituating standard stimulus followed criteron habituation at each intensity. Results indicated that response amplitude for initial, test, and dishabituation responses was a direct function and that habituation rate (trials-to-criterion) was an inverse function of stimulus intensity. Extraverts habituated more rapidly than introverts at high intensity and gave smaller test and dishabituation responses. Some results differed when regression coefficients defined habituation rate and when first stimulus intensities alone were examined. Correlations among initial, test, and dishabituation responses and between each of these and the two measures of habituation rate are also reported. Results were interpreted as partially supportive of Eysenck's theory.     

Habituation to repeated stress: get used to it

Habituation, as described in the landmark paper by Thompson et al. [Thompson, R. F., & Spencer, W. A. (1966). Habituation: A model phenomenon for the study of neuronal substrates of behavior. Psychological Review, 73(1), 16–43], is a form of simple, nonassociative learning in which the magnitude of the response to a specific stimulus decreases with repeated exposure to that stimulus. A variety of neuronal and behavioral responses have been shown to be subject to habituation based on the criteria presented in that paper. It has been known for several decades that the magnitude of hypothalamic–pituitary–adrenal (HPA) activation occurring in response to a stressor declines with repeated exposure to that same stressor. For some time this decline has been referred to as “habituation” in the stress neurobiology literature. However, how this usage compares to the definition proposed by Thompson and Spencer has not been systematically addressed. For this special issue, we review the stress neurobiology literature and examine the support available for considering declines in HPA response to repeated stress to be response habituation in the sense defined by Thompson and Spencer. We conclude that habituation of HPA activity meets many, but not all, important criteria for response habituation, supporting the use of this term within the context of repeated stress. However, we also propose that response habituation can, at best, only partially explain the phenomenon of HPA habituation, which also involves well-known negative feedback mechanisms, activation of broad stress-related neural circuitry and potentially more complex associative learning mechanisms.     

Fatigue and alertness in the United States railroad industry part I: the nature of the problem

The railroad industry must actively manage employee fatigue and alertness problems to maintain an optimal level of operational safety and productivity. Given the necessity to operate nights and irregular hours, weekends and holidays under a wide range of physical conditions and service demands, we must explore every reasonable avenue to ensure employees are fit, alert, and well-rested. Effective fatigue management programs must address train crews, dispatchers, signalmen, track workers, and others – both operating and non-operating personnel. Work scheduling is a particular problem in on-call operations because of start-time variability, “call” predictability, and the common use of “shorter-than 24-h work/rest schedules”. Extensive night operations are incompatible with normal circadian rhythms. Staffing limitations often require extensive overtime and reduce the effectiveness of any work schedule. These and other institutional factors significantly contribute to employee sleep deficit and overall fatigue. Lack of alertness and reduced vigilance are related not only to sleep disruption and resulting sleep deficits, but also to cognitive workload, workload transition, the physical working environment, and the design of advanced control systems. Ongoing research into fatigue mitigation and alertness enhancement strategies and into advanced technologies such as Positive Train Control (PTC) can lead to improvements. These include better labor–management agreements, more effective fatigue-related educational programs, improved schedule regularity, and more practical and adaptable federal laws and regulations.