The nature of error detection as manifested by the error-related negativity was examined in both a Sternberg memory search task and a visual search task. Both tasks were performed in conditions with consistent or varied stimulus–response mapping and loads of three or six letters. After subjects were trained extensively in all conditions, they performed the tasks throughout the night without sleeping. The data suggest that the effectiveness of error detection decreases over time because of a decrease in the quality of perceptual processing. Error detection also suffers when performance requires more search-related resources. In both cases, the representation of the correct response is compromised. These results indicate that error detection depends on the same perceptual and cognitive processes that are required for correct performance.

Two psychophysiological measures, poor suppression of midlatency auditory-evoked responses in a paired stimulus paradigm and ocular motor abnormalities, may index genetic liability for schizophrenia. An important feature of these measures is that both patients and their nonpsychotic relatives exhibit basically the same performance. These measures may be successful endophenotypes for schizophrenia because they assess poor response inhibition associated with dysfunction of dorsolateral prefrontal cortex circuitry. Data bearing on this hypothesis are reviewed, and it is posited that assessment of the auditory-evoked gamma band response and saccade measures of inhibitory abilities are the most valid behavioral measures of schizophrenia's neuropathological correlates. The extant data suggest that psychophysiological studies of schizophrenia can provide consistent and theoretically meaningful information for localizing neuropathology and for assessing the genetics of this complex disorder.

The ability of left-hemisphere stroke patients (n = 8) and healthy control subjects (n = 8) to process sounds preattentively and attentively was studied by recording auditory event-related potentials (ERPs) and behavioral responses. For the right-ear stimulation, the mismatch negativity (MMN) was significantly smaller in the patients than control subjects over both hemispheres. For the left-ear stimuli, the MMN was significantly smaller in the patient group than in the control group over the left hemisphere, whereas no group differences were obtained over the right hemisphere. In addition, the N1 amplitude was reduced bilaterally for the right-ear stimulation (with the reduction being larger over the left hemisphere), whereas no significant effects on the N1 amplitude were found for the left-ear stimulation. Behaviorally, the patients detected significantly fewer deviant tones than did the control subjects irrespective of the stimulated ear. The present results thus suggest that the long-latency ERPs can be used to probe such auditory processing deficits that are difficult to define with behavioral measures. Especially by recording MMN to monaural stimuli, the discrimination accuracy can be separately determined for the left and right temporal lobes.

The P3 amplitude is augmented by decrements in target-probability, increments in the number of nontargets preceding the target, and extensions of the interstimulus interval (ISI). Each of these changes prolongs the target-to-target interval (TTI) and, consequently, results attributed to these factors might, at least partially, be accounted for by the TTI. Recent research also indicates that the P3s elicited by targets in one-, two-, and three-stimuli tasks (in which the TTI remains invariant) are similar. However, the TTI has not been examined systematically in previous research. The present study had subjects listen to a randomized ISI (0.5, 1, 2, or 4 s) version of the auditory oddball task in which targets occurred after one, two, three, four, or five nontargets. Event-related potentials were analyzed based on ISI, sequential structure, and TTI. The study examined sequence and ISI effects independent of TTI effects and demonstrated that extensions of ISI affected N1 but not P3 amplitude, extensions of TTI enhanced P3 amplitude independent of sequential structure, and sequential structure failed to influence P3 amplitude when TTI was controlled.

Psychophysiological measures such as the lateralized readiness potential (LRP) have been used to study information processing in the Eriksen flankers task. The data provided by these measures are consistent with a continuous flow theory, which proposes that the output of stimulus evaluation is continuously available to the response channels. Cohen et al. (1992) realized this theory in a connectionist model and showed that its behavior corresponded to that of human subjects in the flankers task. We report here a modification of the model and an analysis of the degree to which simulated LRPs (based on the activation functions of the response units of the model) resemble the actual LRPs of human subjects in the same task. Across a variety of different experimental conditions and outcomes, there was a marked correspondence between the simulated and actual LRPs. These observations strengthen the propriety of the connectionist model and of the continuous flow theory on which it is based.

We tested the assumption that the slope of the within-individual regression equation of respiratory sinus arrhythmia (RSA) normalized by tidal volume (VT) upon respiratory cycle length (TTOT) can characterize ventilatory RSA modulation independent of cardiac vagal tone, whereas the intercept is varying as a function of vagal tone. We also explored whether a variation of VT is necessary to estimate slopes reliably. Four 3-min sequences paced at 8–18 cycles/min were performed supine and standing. Participants also breathed the same sequences in supine posture with voluntarily varying VT. The mean slope of RSA/VT upon TTOT was identical, and the mean intercept was lower for standing than supine (spontaneous VT) conditions. Stability of slopes was low between body postures, and was higher between spontaneous VT versus varying VT at the same body posture. The regression of RSA/VT upon TTOT allows for a valid estimation of ventilatory influences on RSA.

We evaluated the effects of selective slow-wave sleep (SWS) deprivation and time-of-night factors on cognitive performance upon awakening. Ten normal men slept for 6 consecutive nights in the laboratory: 1 adaptation, 2 baseline, 2 selective SWS deprivation, and 1 recovery night. Cognitive performance was assessed by means of a Descending Subtraction Task after 2, 5, and 7.5 h of sleep. There was an almost complete selective SWS suppression during both deprivation nights, and a significant SWS rebound during the recovery sleep. Regarding cognitive performance, a progressive linear decrease of sleep inertia upon successive awakenings was found during all experimental nights except for the recovery night. In addition, a significant decrease of sleep inertia was observed upon the morning awakening of the second deprivation night for the measure of performance speed, and a significant increase of sleep inertia upon the morning awakening of the recovery night for the measure of performance accuracy. The results show that cognitive performance upon awakening is adversely affected by sleep depth and that, during the sleep–wake transition, cognitive performance accuracy is more impaired than performance speed.

To assess the processing stages involved in attention shifting and response selection tasks in children, we recorded event-related potentials (ERPs) and performance measures during a variant of the Posner paradigm. Subjects responded to visual targets, either preceded by a spatial cue (valid = same side; invalid = opposite side) or presented uncued. Valid targets evoked high-amplitude P1 responses, single-peaked P3s, and the shortest reaction times (RTs). Invalidly cued stimuli evoked delayed RTs, resulting in part from incorrectly oriented attention (decreased P1) leading to delayed target processing (belated N2-P3). Invalid targets also evoked a positive slow wave attributed to prolonged response selection due to cue/target incompatibility. Uncued stimuli elicited the longest RTs, unexplained by deficits in target detection or response selection, which likely resulted from a deficit in motor preparation due to the lack of warning signal. This method may be applied in clinical settings to disentangle selective processing deficits in target detection, response selection, or motor preparation stages.

The effects of fragrance on sexual response in women were investigated using subjective and physiological measures of sexual arousal and of mood. Responses were obtained from female participants in three different fragrance conditions (female fragrance, male fragrance, and a “blank” or neutral substance), as they viewed erotic and sexually neutral films, and fantasized about sexual situations. Each woman was tested twice: during the midfollicular and periovulatory phases of her menstrual cycle. Menstrual cycle phase effects were apparent; self-report data indicated greater sexual arousal and more positive mood during the periovulatory than during the follicular phase. Results demonstrated a positive effect of the male fragrance on genital arousal during erotic fantasy, but this finding was apparent only during the follicular phase testing session. This effect did not appear to be mediated by any effects of fragrance on mood.

We investigated emotional disturbances in 36 schizophrenia patients, 48 of their first-degree relatives, and 56 controls to determine if abnormal affective startle modulation could be associated with genetic risk for schizophrenia. Both patients and relatives had a pattern of startle modulation indistinguishable from controls, with potentiated startle amplitude while viewing negative valence slides and attenuation while viewing positive slides. Patients with flat affect did not differ from those without in startle modulation or slide ratings. The patients and their relatives had lower pleasantness ratings of positive slides and the patients had higher pleasantness ratings of the negative slides than controls. The startle paradigm may not be useful for identifying individuals with a genetic liability for schizophrenia. The results suggest that low-level defensive and appetitive behaviors are unaffected in schizophrenia.

This study examined physiological response to an encounter with and touch by an unfamiliar person. Fifty-five African American (23 male, 30 female) and 51 European American (23 male, 28 female) undergraduates participated. A Black or White interactor entered the room, introduced himself or herself, checked equipment for 30 s, and then took a pulse for 30 s. Entry of the interactor resulted in increased corrugator and zygomaticus facial muscle activity (EMG), increased skin conductance (SC), and heart rate (HR) acceleration. Corrugator EMG was greater among Black subjects; White subjects responded with more zygomatic EMG and SC and greater HR acceleration. Women showed a more positive facial expression than did men. Being touched reduced EMG and HR but resulted in increased SC. White and Black males showed more HR acceleration when encountering a Black male interactor.

This study examined physiological response to an encounter with and touch by an unfamiliar person. Fifty-five African American (23 male, 30 female) and 51 European American (23 male, 28 female) undergraduates participated. A Black or White interactor entered the room, introduced himself or herself, checked equipment for 30 s, and then took a pulse for 30 s. Entry of the interactor resulted in increased corrugator and zygomaticus facial muscle activity (EMG), increased skin conductance (SC), and heart rate (HR) acceleration. Corrugator EMG was greater among Black subjects; White subjects responded with more zygomatic EMG and SC and greater HR acceleration. Women showed a more positive facial expression than did men. Being touched reduced EMG and HR but resulted in increased SC. White and Black males showed more HR acceleration when encountering a Black male interactor.

Studies of concurrent central, and autonomic activity using a conventional event-related potential (ERP) oddball paradigms, are considered useful in elucidating the relationship between central and autonomic responses, but the autonomic response tends to overlap. A new method was used to decompose and score overlapping skin conductance responses (SCR). This method enabled examination of dynamic relationships of phasic SCR, prestimulus electroencephalogram (EEG), and ERP to auditory target stimuli in 50 normal adults. SCR amplitude was negatively correlated to EEG and N200 amplitude. The SCR amplitude changes over time exhibited an exponential decline opposite to those of N200, alpha, and beta. All the fitted exponential functions had a time constant of 1–2 min. The findings suggest that a N200 component, active in the auditory sensory discrimination, is concomitant with the SCR. The narrow range of the time constant may provide a clue to the conjoint processes underlying central and autonomic adaptive functions.

The effects of attentional set on subjective magnitude ratings, spinal reflexes, and somatosensory evoked potentials (SEP) elicited by innocuous and painful sural nerve stimulation were investigated in 24 subjects. Cuing stimuli informed subjects as to whether a visual identification or a somatosensory rating task would follow. Twenty percent of the trials were invalidly cued, where the subjects were expecting a visual stimulus but were given a sural nerve stimulus and vice versa. Subjective magnitude ratings were lower in the invalidly cued condition than the validly cued condition. Attentional set had no effect on innocuous-related spinal or early cortical responses, nor on the spinal nociceptive withdrawal reflex. The pain-related negative difference potential (NDP) and P2 component of the SEP were largest in the invalidly cued condition. These results provide further support for our hypothesis that the NDP is generated in part by the anterior cingulate, and suggest that the anterior cingulate response to pain reflects non-pain-specific cognitive processes (e.g., orienting attention towards important stimuli in the environment and/or response competition) and not some aspect of the pain experience. The effects of attentional set on the pain-related P2 suggests that it might correspond to the P3a event-related potential. If this is the case, the pain-related P2 could serve as a useful index of neural processes involved in the cognitive-evaluative aspect of pain.

A. R. Haig, E. Gordon, and S. Hook (1997) disputed G. McCarthy and C. C. Wood's (1985) contention that scaling should be used when assessing the statistical significance of between condition (or group) differences in the shapes of event-related potential (ERP) scalp topographies. Haig et al. based their contention upon the lack of empirical realism in McCarthy and Wood's model of within-group ERP noise, claiming that McCarthy and Wood's results could not be generalized to realistic ERP data. We argue, on both empirical and theoretical grounds, that Haig et al. do not make a compelling case against generalization of McCarthy and Wood's results. Moreover, Haig et al.'s conclusion is based upon a misconception of how scaling should be used. We conclude that when a quantitative measure of differences between topographic shapes is needed, scaling is not an option—it is a requirement.

Contralateral-control methods can be applied to psychophysiology and in particular to the study of visual memory. Visual memory possesses some degree of hemispheric organization, so that visual memory traces for laterally presented stimuli are stronger or more durable in the hemisphere contralateral to the hemifield where the stimuli were first presented. I first introduce the concept of hemispheric organization of function. Then I discuss how hemispheric organization can be exploited for obtaining information about the time course and brain localization of psychological processes, using a contralateral-control method. Behavioral and event-related brain potential data support the hemispheric organization view of visual memory, and the contralateral-control method, in conjunction with the recording of the event-related optical signal, can be used to reveal the existence of memory-driven processes in early stations of the visual system.

A quantitative, theory-driven model of hemodynamics was developed, relating reactivity in blood pressure to orthogonal dimensions of “hemodynamic profile” and “compensation deficit,” which were derived from the (multiplicative) interaction of cardiac output and total peripheral resistance. A Finapres 2300e was used to estimate blood pressure, cardiac output, and total peripheral resistance in 100 healthy men and women during mental arithmetic and cold pressor tasks on two occasions. Results were consistent with model predictions. As predicted, cardiac output and peripheral resistance reactions were curvilinearly related, and blood pressure reactivity was strongly related to compensation deficit (r = .76–.89). Conversely, the orthogonally defined hemodynamic profile remained independent of blood pressure reactivity (r = .11 or less). The data show that the present model overcomes several difficulties and inconsistencies in previous attempts to obtain an independent measure of hemodynamic profile. The new model could help to elucidate sources of cardiovascular pathogenesis not suggested from the study of blood pressure reactivity alone.

The effect of aerobic training on parasympathetic reactivity to mental stress is unclear. Thus, the parasympathetic response, as assessed by time series analysis of heart period variability (HPVts), of 10 trained male runners (trained group), 10 inherently low resting heart rate untrained men (low HR group), and 10 normal resting HR men (control group) at rest and to two mental stressors was examined. Participants completed a mental arithmetic and Stroop task. Resting HPVts at high and medium frequencies was significantly greater for the trained and the low HR groups than for the control group. Significantly greater decreases in HPVts at the medium frequency during arithmetic recovery were measured for the trained and low HR groups compared with the response of the control group. Significantly greater decreases in HPVts at both the the high and medium frequencies during the first two epochs of the Stroop occurred only for the trained and low HR groups. These results suggest that the greater HPVts at rest and decline in HPVts during and after mental challenge is influenced by both aerobic training and genetic inheritance.

Facial flushing was studied in 38 young women who scored high or low on trait anger. To induce anger in the subjects, their task was to solve a difficult puzzle, with or without harassment from a female research assistant. Facial blood flow increased in response to provocation, together with increases in cardiovascular and electrodermal activity. Flushing was associated with large increases in electrodermal activity and small increases in diastolic blood pressure. Subjects high in trait anger reported most anger and embarrassment, but physiological activity did not differ from subjects with low trait anger. The findings suggest that sympathetically mediated vasodilatation in facial blood vessels competes with cutaneous vasoconstriction during anger. Unpleasant sensations of facial warmth might heighten aversive emotional experiences, but dilatation of facial blood vessels could also act as a type of “safety valve” by opposing increases in blood pressure. An angry predisposition may influence the subjective experience of anger in women, but does not seem to have a major influence on physiological reactivity to mild provocation.

Thought disorder in schizophrenia may involve abnormal semantic activation or faulty working memory maintenance. Event-related potentials (ERPs) were recorded while sentences reading “THE NOUN WAS ADJECTIVE/VERB” were presented to 34 schizophrenic and 34 control subjects. Some nouns were homographs with dominant and subordinate meanings. Their sentence ending presented information crucial for interpretation (e.g., The bank was [closed, steep]). Greatest N400 activity to subordinate homograph-meaning sentence endings in schizophrenia would reflect a semantic bias to strong associates. N400 to all endings would reflect faulty verbal working memory maintenance. Schizophrenic subjects showed N400 activity to all endings, suggesting problems in contextual maintenance independent of content, but slightly greater N400 activity to subordinate endings that correlated with the severity of psychosis. Future research should help determine whether a semantic activation bias in schizophrenia toward strong associates is reflected in ERP activity or whether this effect is overshadowed by faulty verbal working memory maintenance of context.