The purpose of the study was to examine the hypothesis that distractibility is a fundamental characteristic of mild closed head injury (MHI). The claim that cognitive symptoms in MHI are due to a mild type of frontotemporal injury was also investigated. Cognitive event-related potentials (ERPs), accuracy and reaction time to target stimuli in a dichotic listening paradigm, and neuropsychological test results were studied in patients with MHI (N = 15), patients with verified frontal lobe damage (N = 10), and healthy controls (N = 13). Information processing reflecting target detection (N2, P3b) and sustained selective attention (processing negativity) was studied. The MHI and frontal patients did not differ on behavioral measures, except that the MHI group had significantly longer reaction times to target stimuli in the ERP task. Both patient groups had deviant ERPs compared with controls, but their ERP patterns differed in important respects. Contrary to expectations, the MHI patients had the most abnormal ERPs. They showed significantly smaller N2 and Nd amplitudes than frontal patients and controls, indicating that the mediating cognitive mechanisms were not equivalent in MHI and frontal injury. The data suggest that MHI patients allocated less processing resources to the task than either the control subjects or the patients with frontal lobe damage.

Cardiovascular activity was measured at resting baseline and in response to a car racing game, undertaken in competition or in cooperation with an experimenter, or individually. Competitiveness and win and goal orientations were assessed by questionnaire. Competition provoked increases in blood pressure and heart rate, and a significant shortening of the preejection period, an index of enhanced beta-adrenergic influences on the heart. The cooperation task was largely without effect, and although the solo task affected cardiovascular activity, it did so to a lesser extent and much less consistently than did the competition task. The three task conditions, then, were largely distinguishable by their capacity to activate beta-adrenergic processes. Participants high in competitiveness and desire to win showed higher blood pressure reactions and greater shortening of the preejection period to competition than those low in these characteristics.

Latent growth curve methodology was used to model systolic blood pressure reactivity and recovery from the cold pressor test. A piecewise regression approach permitted the separate but simultaneous modeling of the two components (reactivity and recovery) of the stress process. Data came from a study of 99 participants classified on the basis of gender, ethnicity, and family history of hypertension. Their systolic blood pressure was assessed at rest, during the cold pressor test, and during a task recovery period. A measure of task appraisal and readings from ambulatory blood pressure monitoring during a workday were also examined. The article illustrates a step-by-step approach to modeling reactivity and recovery. Results indicated that both reactivity and recovery were associated with subsequent systolic blood pressure at work.

Associations between trait dominance and cardiovascular reactivity were examined in previously unacquainted healthy men and women. Subjects participated in three mixed-gender dyadic interactions with the same partner while their cardiovascular responses were assessed. Among men, but not women, trait dominance was positively and significantly associated with systolic blood pressure reactivity. For men and women, diastolic blood pressure reactivity was positively and significantly associated with trait dominance while participants prepared to interact and with partner's trait dominance while they interacted. All effects held after controlling for trait hostility. Dominance merits attention as a correlate of cardiovascular reactivity, a finding that parallels emerging patterns in the cardiovascular disease literature. Gender and gender-related social factors as potential moderators of this relationship are discussed.

The concept of physiological individual response specificity (IRS) was critically discussed. A review of empirical studies focused on IRS magnitude, stability, and personality correlates. Using difference scores, an average of 33% of the participants showed a significant IRS. IRS stability was found in only 15% of the participants. In some studies, IRS incidence was associated with neuroticism or stress coping styles. We suggest that the IRS concept should include not only purely constitutional but also situational and psychological determinants. Predictions from this revised biopsychological model were tested with a data set comprising 48 healthy male participants who completed six tasks, which were replicated three times in 1-week intervals. At Session 1, 21% of the participants displayed a significant IRS. IRS stability was found in only 8% of the participants. Participants with a significant IRS at Session 1 reported higher levels of fear (anger and happiness as covariates) and of pounding heart. Between-session IRS (trait-IRS) but not within-session IRS (state-IRS) was associated with trait anxiety.

A sensitive electronic monitor (Mini-Motionlogger, Ambulatory Monitoring Inc.) attached to the wrist was used to record movements during two 24-hr days of ambulatory blood pressure (BP) and heart rate (HR) recording in 65 women and 54 men between the ages of 55 and 79 years, all of whom were in good health. The objective was to examine the relationship between various measures of physical activity and ambulatory BP and HR during waking and sleeping periods and during various diary-defined behaviors. For waking and sleeping periods, neither the mean nor the variability of the activity measure was associated with the mean or variability of the ambulatory BP and HR measures in between-subjects correlational analyses. Within-subject analyses showed little evidence of significant covariation between activity and BP or HR during either waking or sleeping conditions with most participants showing a slightly positive association. The activity measure discriminated between behaviors associated with little effort (watching television) versus more energetic behaviors (walking). Activity accounted for a relatively small amount of the difference in BP or HR related to overall state (wake, sleep), posture (stand, sit), and social condition (being with family vs. being with friends). The utility of electronic activity monitoring for studies of BP and HR in natural settings is discussed.

In the present study we investigated the relationship between detecting violations of structural regularities of tone sequences and detecting deviations from temporal regularities or repetitive spectral auditory stimulus features. Twelve subjects were presented with randomized sequences of two tones (differing both in frequency and intensity) delivered alternately to the left and right ears at a constant stimulus onset asynchrony (SOA). In separate blocks, occasional deviant stimuli broke one, two, or three of the following regularities: spatial alternation, the constancy of SOA, or the dominant frequency-intensity conjunctions. Unlike the mismatch negativity (MMN) elicited by alternation-plus-SOA deviants, the MMN elicited by alternation-plus-conjunction deviants was approximately equal to the sum of the two corresponding single-deviant MMNs. These results suggest that the preattentive change-detection system processes infrequent violations of the structural regularities of sound sequences together with changes in temporal regularities, but separately from changes in repetitive spectral sound features. The MMN elicited by the triple-deviant stimuli corroborated these conclusions.

Rhythmic properties of spoken language such as metrical stress, that is, the alternation of strong and weak syllables, are important in speech recognition of stress-timed languages such as Dutch and English. Nineteen subjects listened passively to or discriminated actively between sequences of bisyllabic Dutch words, which started with either a weak or a strong syllable. Weak-initial words, which constitute 12% of the Dutch lexicon, evoked more negativity than strong-initial words in the interval between P2 and N400 components of the auditory event-related potential. This negativity was denoted as N325. The N325 was larger during stress discrimination than during passive listening. N325 was also larger when a weak-initial word followed a sequence of strong-initial words than when it followed words with the same stress pattern. The latter difference was larger for listeners who performed well on stress discrimination. It was concluded that the N325 is probably a manifestation of the extraction of metrical stress from the acoustic signal and its transformation into task requirements.

Physiological stress reactivity has been examined with respect to cynical hostility and anger expression, but primarily among Caucasians. Investigations of African Americans are far fewer and have focused only on the cardiovascular system. This study compared the relationships between hostility and anger expression on the one hand, and both cardiovascular and lipid reactivity on the other, among African Americans and European Americans. Forty-six men participated in a study examining cardiovascular and lipid reactivity to a speech stressor. African American men low in cynical hostility had greater blood pressure reactivity to the stressor; this effect appeared to be due primarily to low cynical men with high Anger In. Independent of ethnicity, those with a general tendency to either always express or always inhibit the expression of anger had higher triglyceride reactivity, relative to those with a more flexible style of anger expression. These results suggest that it is important to examine ethnicity in relationship to measures of hostility and anger expression, to uncover vulnerable individuals.

This study of 31 college students employed the startle eye-blink modification (SEM) technique to index both early and later stages of attentional processing during a memory-load version of the Continuous Performance Test (CPT). Participants viewed a series of digits and pressed a button after the digit 7 of each 3–7 sequence. A startling noise burst was presented either 120 or 1,200 ms following three preselected prepulses: target (3), nontarget (non-3 and non-7 digits), or target plus distractor (3 and simultaneous tone distractor). Greater startle inhibition occurred 120 ms following target and target-plus-distractor prepulses compared with nontargets, indicating early selective attention. No difference was observed between SEM during target and target-plus-distractor prepulses, suggesting the distractor was effectively ignored. At 1,200 ms, the three prepulse types produced nondifferential inhibition, suggesting that modality-specific selective attention occurs in anticipation of the presentation of the next CPT prepulse. These findings indicate that SEM distinguishes between different early selective attention and later anticipatory attention subprocesses underlying the CPT.

This study investigated the validity of procedures for estimating the P3 complex in single trials. In “pseudo-real” simulations of the N1-P2 complex of the occipital visual-evoked potential, Möcks, Köhler, Gasser, and Pham (1988) had reported that their maximum-likelihood method (Pham, Möcks, Köhler, & Gasser, 1987) performed better than Woody's (1967) method. Using pseudo-real simulations of auditory oddball data, we wanted to know whether this finding also held true for the P3 complex. The performance of three methods was studied: peak picking, Woody's method, and Pham et al.'s method (as well as an extension of this latter method). Performance of all methods critically depended on the signal-to-noise ratio. There was some advantage for the more sophisticated methods, particularly when signal-to-noise ratios were realistic. “Good” trials may be selected by all methods, to improve the signal-to-noise ratio, but this selection entails the risk of bias. Further research should investigate whether these conclusions also hold true when the P3 complex consists of more than one component.

Temporal auditory processing deficits are thought to play an important role in some pathologies of speech understanding difficulties. The purposes of the present study were to determine whether short silent gaps within a pure tone can be used to elicit mismatch negativity (MMN) as an objective measure of temporal resolution, and to investigate the relation between MMN and performance on a behavioral gap-detection task. The stimuli used for both tasks were 1-kHz sinusoids presented in a low-pass masking noise. Behavioral gap-detection thresholds were determined using an adaptive three-alternative forced-choice procedure. To elicit MMN, a series of deviant stimuli with varying gap durations was generated and presented in an oddball paradigm among standard stimuli without a gap. Only the gaps larger than the mean behavioral gap-detection threshold evoked a clear MMN. There was no clear relation between psychoacoustic and MMN thresholds.

A recent positron emission tomography (PET) study on brain mechanisms in classical, or Pavlovian, conditioning is reviewed. The PET data were compared with skin conductance data recorded off-line. The participants were five men who participated in three different experimental phases. In the first (habituation) phase, a tone was repeated 24 times at random intervals. In the second (acquisition) phase, the tone was paired with a brief shock to the wrist. In the third (extinction) phase, the tone was presented alone again. Statistical parametric mapping analysis of the PET data showed significantly increased activation of the right hemisphere in the orbitofrontal cortex, dorsolateral prefrontal cortex, inferior and superior frontal cortices, and inferior and middle temporal cortices. In the left hemisphere, only Area 19 and the superior frontal cortex showed significant activation. The findings are discussed within a theoretical framework that argues for different brain mechanisms in acquisition and extinction in classical conditioning.

We examined developmental differences in smooth pursuit eye tracking proficiency in a large sample of preadolescent, adolescent, and adult males. Smooth pursuit was quantified using general measures of oculomotor functioning and by examining the frequency and dynamic characteristics of specific saccadic events. Examination of age effects using general measures indicated that, by late adolescence, the smooth pursuit system reached adult levels of functioning. No significant differences were found between the adolescent and adult groups on most global measures. However, both groups had better eye tracking than the preadolescent group, suggesting that during preadolescence the oculomotor system is still developing and is not yet capable of optimal performance. Examination of the frequency and dynamic characteristics of the saccadic events yielded additional information regarding the nature of the smooth pursuit eye tracking differences of the three age groups.

We evaluated the effects of two laboratory stressors (speech preparation and isometric handgrip) on gastric myoelectrical and autonomic cardiac activity, and the extent to which autonomic responses to these stressors and somatization predict reports of motion sickness during exposure to a rotating optokinetic drum. Both stressors prompted a decrease in preejection period (PEP) and respiratory sinus arrhythmia (RSA), and an increase in a dysrhythmic pattern of gastric myoelectrical activity, termed gastric tachyarrhythmia. Stressor-induced decreases in RSA and higher somatization scores predicted increased reports of motion sickness during drum rotation. These results demonstrate that laboratory stressors concurrently affect gastric myoelectrical activity and autonomic control of the heart, and that stressor-induced decreases in RSA and higher levels of somatization predict motion sickness susceptibility.

Distinctive words elicit the P300 component of the event-related brain potential, and are also likely to be recalled. Previous studies have shown that the larger the P300 elicited by distinctive words, the more likely it is that those words will be recalled. The present study addressed whether this relationship is affected by the manner in which distinctiveness is induced. Distinctiveness was manipulated either by varying the size of the characters in which a word was displayed, or by surrounding the word with a frame at close or far distance. All distinctiveness attributes resulted in improved recall performance. The words whose size was distinctive elicited a large P300, and P300 amplitude was larger for subsequently recalled words. The frame attributes elicited a small P300, and the amplitude of these P300s was not correlated with subsequent recall performance. Instead, a frontal slow wave was correlated with subsequent recall performance in the far frame group. It is concluded that the relationship between P300 amplitude and subsequent recall depends on the type of distinctiveness attribute, and should therefore not be ascribed to a generalized effect of distinctiveness on memory encoding processes.

Participants in Experiments 1 and 2 performed a discrimination and counting task to assess the effect of lead stimulus modality on attentional modification of the acoustic startle reflex. Modality of the discrimination stimuli was changed across subjects. Electrodermal responses were larger during task-relevant stimuli than during task-irrelevant stimuli in all conditions. Larger blink magnitude facilitation was found during auditory and visual task-relevant stimuli, but not for tactile stimuli. Experiment 3 used acoustic, visual, and tactile conditioned stimuli (CSs) in differential conditioning with an aversive unconditioned stimulus (US). Startle magnitude facilitation and electrodermal responses were larger during a CS that preceded the US than during a CS that was presented alone regardless of lead stimulus modality. Although not unequivocal, the present data pose problems for attentional accounts of blink modification that emphasize the importance of lead stimulus modality.

A. Öhman and J.J.F. Soares (1994) demonstrated that masked presentation of phobic pictures produces increased skin conductance responses (SCRs) in phobic subjects. A. Öhman (1993) explained this phenomenon in terms of a hypothetical “feature detector” that identifies physical characteristics of stimuli and activates the arousal system without involving significance evaluation or consciousness. By exposing spider phobics to spider words, general threat words, and neutral words instead of pictures, this explanation was tested. Words were presented both masked and unmasked while electrodermal activity was measured. Under unmasked conditions, SCRs were largest for spider words followed by general threat words, then neutral words. When masked, the difference between spider words and general threat words disappeared but SCRs remained significantly smaller for neutral words. It is concluded that activation of the arousal system by masked threat cues does not necessarily depend on their perceptual characteristics.

Participants in Experiments 1 and 2 performed a discrimination and counting task to assess the effect of lead stimulus modality on attentional modification of the acoustic startle reflex. Modality of the discrimination stimuli was changed across subjects. Electrodermal responses were larger during task-relevant stimuli than during task-irrelevant stimuli in all conditions. Larger blink magnitude facilitation was found during auditory and visual task-relevant stimuli, but not for tactile stimuli. Experiment 3 used acoustic, visual, and tactile conditioned stimuli (CSs) in differential conditioning with an aversive unconditioned stimulus (US). Startle magnitude facilitation and electrodermal responses were larger during a CS that preceded the US than during a CS that was presented alone regardless of lead stimulus modality. Although not unequivocal, the present data pose problems for attentional accounts of blink modification that emphasize the importance of lead stimulus modality.

The present study investigated the effects of lead stimulus modality on modification of the acoustic startle reflex during three reaction time tasks. In Experiment 1, participants (N = 48) were required to press a button at the offset of one stimulus (task relevant) and to ignore presentations of a second (task irrelevant). Two tones that differed in pitch or two lights served as signal stimuli. Blink startle was elicited during some of the stimuli and during interstimulus intervals. Skin conductance responses were larger during task-relevant stimuli in both groups. Larger blink facilitation during task-relevant stimuli was found only in the group presented with auditory stimuli, whereas larger blink latency shortening during task-relevant stimuli was found in both groups. Experiment 2 (N = 32) used only a task-relevant stimulus. Blink magnitude facilitation was significant only in the group presented with tones, whereas blink latency shortening was significant in both groups. Experiment 3 (N = 80) used a go/nogo task that required participants to press a button if one element of a compound stimulus ended before the second, but not if the asynchrony was reversed. The offset asynchrony was varied between groups as a manipulation of task difficulty. Startle magnitude facilitation was larger during acoustic than during visual stimuli and larger in the easy condition. The present data indicate that startle facilitation in a reaction time task is affected by stimulus modality and by task demands. The effects of the task demands seem to be independent of lead stimulus modality.