Olfactory event-related potentials (OERPs) were recorded monopolarly at the Fz, Cz, and Pz electrode sites in 16 young adults and 16 older adults to assess aging effects on the olfactory P3. Amyl acetate was used to elicit the OERPs, with an intertrial interval of 45 s. Young adults produced significantly larger P3 amplitudes and shorter P3 peak latencies than older adults. The olfactory P3 response appears to be sensitive to age-related changes in the olfactory system and may reflect cognitive slowing in the central nervous system.

In the present study, we examined whether the use of partial information for response preparation depends on the utility of that partial information for meeting task demands. Using a choice/Nogo task, the utility of the partial information was varied by manipulating the proportion of Go relative to Nogo signals, and preliminary response preparation was indexed by the degree of lateralized readiness potential (LRP) activity on Nogo trials. The Nogo LRP was clearly present when Go probability was high (67% Go) and, to a lesser extent, when Go and Nogo signals were equiprobable. However, the Nogo LRP disappeared when the probability of a Go signal was low (25% Go). This pattern of results supports the hypothesis that response preparation will be based on partial stimulus information only when the information has significant utility in the context of the overall task requirements.

Alterations in a number of measures of cardiac activity were examined during sleep onset in 6 participants over 3 experimental nights. Each sleep onset was divided into four consecutive phases: wakefulness, mixed alpha and theta activity, stage 2 NREM sleep with arousals, and stable stage 2 sleep. The variables measured were heart rate (HR), respiratory sinus arrhythmia (RSA), pre-ejection period (PEP) and T-wave amplitude (TWA). Respiration rate (RR) was also measured. HR and RR were lower in stable Stage 2 sleep compared with wakefulness, whereas PEP, TWA and RSA did not change significantly. During the second and third phases of sleep onset, HR decreased at each transition into sleep and increased following each spontaneous arousal. This increase resolved rapidly, with a return to sleep levels by 12 beats after the arousal. HR changes are discussed with reference to RSA, PEP, TWA and the concept of a waking reflex.

We investigated if incongruent solutions of simple multiplication problems would elicit similar event-related brain potentials as inappropriate words in sentences. In Experiment I, 12 subjects verified the appropriateness of solutions of multiplication problems or of final words in short sentences. Both incongruent solutions and incongruent words evoked a phasic negative shift between 300 and 500 ms having a similar topography. In Experiment II, we tested with another sample of 13 subjects if the amplitude of this arithmetic N400 effect was affected differently by different stimulus onset asynchronies (SOA = 200 and 500 ms) and by errors that were either table-related or table-unrelated to the preceding operands. Again, incorrect solutions elicited an arithmetic N400 effect whose amplitude depended on both the relatedness of the solution and the SOA. The ascending part of the N400 effect was always larger for unrelated than for related errors independently of the SOA, whereas the maximum of the N400 effect was larger for unrelated errors in case of a long SOA only. This pattern of effects was similar to that observed with semantic material varying lexical associations. These results suggest that arithmetic incongruencies are handled by the system in a manner functionally similar to that of semantic incongruencies.

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.

Thoracic impedance is modulated by events within the respiratory cycle, which represents a source of “noise” in impedance cardiography. Respiration itself, however, is a physiological rhythm of interest to psychophysiologists. We report here methods and validation for deriving impedance pneumographic measures of respiration from impedance cardiography signals, based on standard tetrapolar band electrodes. We recorded the change in impedance (ΔZ), the first derivative of the change in impedance (dZ/dt), output from a strain-gauge respirometer, and criterion spirometry from eight healthy adults during rest, paced breathing, abdominal breathing, thoracic breathing, and a mental arithmetic task. Transfer function analyses revealed that a ΔZd signal (derived by integration of the dZ/dt signal) provided the best estimate of the criterion spirometric measure for all parameters (coherence, phase, and gain), accounting for almost 90% of the variance in respiratory waveform morphology. The results document the potential utility of impedance pneumography, as derived from standard impedance cardiography signals.

Performance on heartbeat counting tasks is usually interpreted in terms of cardiac sensitivity. We tested the hypothesis that heartbeat counting is influenced by beliefs about heart rates by dissociating beliefs about heart rates and actual heart rates. In a within-subjects design, heart rates of 50 patients with cardiac pacemakers were set to a low (50 bpm), medium (75 bpm), or high (110 bpm) pacing rate unknown to the patients via remote control while they performed a heartbeat tracking task. Results showed that patients' heartbeat counting did not follow the shifts in their actual heart rates adequately, although their overall performance was comparable to that of young and healthy control participants. As a result, tracking scores decreased significantly in the high pacing rate condition where beliefs about heart rates and actual heart rates were most extremely dissociated. The findings suggest that tracking scores reflect beliefs about heart rates rather than cardiac sensitivity.

Variation of the P300 component was studied in normal children and adults during an auditory oddball paradigm. In children, the target stimuli that were preceded by a large number of standard stimuli elicited about twice as large P300 with a significantly shorter latency, a more widespread distribution, and an earlier positivity in the frontal area than those that were preceded by a small number of standard stimuli. The P300 variation was not as marked in adults as in children. Based on the context updating theory of the P300, the finding suggests that a long intertarget interval (ITI) results in a profound decay of the neural representation of the target stimulus in children; consequently, more resources are needed to update the neural representation, and the target may even be processed as a novel input. The P300 variation may provide information about the brain functions related to memory, attention, and orienting in children. This variation should be considered when assessing cognitive brain functions with event-related potentials in children.

This study examined the effect of response selection and execution on P3 latency during the performance of simple reaction time (RT) and stimulus–response compatibility tasks. Response time on these tasks was defined in terms of RT and movement time (MT). Event-related brain potentials were recorded from 67 female participants concurrently with the performance measures. On the simple RT task, the distance of the response button from the home button was varied (7, 15, and 23 cm). When stimulus evaluation demands were minimal, response execution affected P3 latency, with increased response button distance resulting in increased P3 latency. However, these movement effects were modest, and in most protocols, would not be a confounding factor. The stimulus–response compatibility task examined the interaction of stimulus evaluation demands and response requirements. RT, MT, and P3 latency were affected by stimulus congruency, whereas RT and P3 amplitude were affected by response compatibility.

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.

Our recent work suggests that innocuous somatosensory activity elicited by a brief electrical stimulus is inhibited by pain evoked by the same electrical stimulus but not by pain evoked by continuous heat. These results led to the hypothesis, tested in the present experiment, namely that pain only inhibits innocuous somatosensation when the painful and innocuous stimuli have short durations and close temporal and spatial overlap. A painful 200-ms laser pulse did not produce a decrease in the perceived magnitude of the innocuous electrical stimulus or in the amplitude of a scalp potential that earlier work suggested is generated by neurons involved in innocuous somatosensation. Hence, the pain-related inhibition of innocuous somatosensation observed in these electrical studies cannot be attributed solely to the duration or to the temporal and spatial overlap of the innocuous and painful stimuli. Laser pain did produce a small increase in the subjective magnitude of the innocuous electrical stimulus, which the electrophysiological evidence suggests might be due to a change in the late- but not the midlatency responses in the central innocuous somatosensory pathways.

College undergraduates were identified as alexithymic or control, based on their scores on the Toronto Alexithymia Scale (TAS; Taylor, Ryan, & Bagby, 1985). All subjects were presented standardized emotion-eliciting color slides for 6 s while facial muscle, heart rate, and skin conductance activity were recorded. Stimuli were presented a second time while subjects were asked to provide emotion self-reports using a paper-and-pencil version of the Self-Assessment Manikin (SAM; Lang, 1980) and to generate a list of words describing their emotional reaction to each slide. Consistent with the definition of alexithymia as a syndrome characterized, in part, by a deficit in the identification of emotion states, high TAS subjects supplied fewer emotion-related words than did controls to describe their response to the slides. Alexithymics also indicated less variation along the arousal dimension of the SAM, produced fewer specific skin conductance responses and showed less heart rate deceleration to the slides, regardless of category. No valence-related differences between alexithymic and control subjects were noted.

Event-related potentials (ERPs) provide a noninvasive method to evaluate neural activation and cognitive processes in schizophrenia. The pathophysiological significance of these findings would be greatly enhanced if scalp-recorded ERP abnormalities could be related to specific neural circuits and/or regions of the brain. Using quantitative approaches in which scalp-recorded ERP components are correlated with underlying neuroanatomy in schizophrenia, we focused on biophysical and statistical procedures (partial least squares) to relate the auditory P300 component to anatomic measures obtained from quantitative magnetic resonance imaging. These findings are consistent with other evidence that temporal lobe structures contribute to the generation of the scalp-recorded P300 component and that P300 amplitude asymmetry over temporal recording sites on the scalp may reflect anatomic asymmetries in the volume of the superior temporal gyrus in schizophrenia.

We investigated the nature of event-related potential (ERP) effects in a handedness recognition task requiring mental rotation. Thirty subjects were tested with rotated and sometimes reflected alphanumeric characters while ERPs were recorded from 18 electrodes. On each trial, a cue provided valid information about the angular displacement of the following probe. This design allowed a distinction between three processing episodes: evaluation of the difficulty of the forthcoming task, preparation for the task, and the mental rotation task itself. The three episodes were accompanied by distinct ERP effects having distinct polarities, a different rank order of amplitudes for different probe orientations, and a different topography. These data confirm previous findings showing that mental rotation is accompanied by a parietal negativity. However, they also suggest that the rotation-related negativity found after tilted stimuli in standard mental rotation tasks is most likely overlapping with another, simultaneously triggered ERP effect functionally related to an evaluation of task difficulty.

In this study, we examined the relationship between the novelty P3 and the P300 components of the brain event-related potential (ERP). Fifteen subjects responded manually to the rare stimuli embedded either in a classical auditory oddball series or in a series in which “novel” stimuli were inserted. The electroencephalogram (EEG) was recorded with a dense array of 129 electrodes. The data were analyzed by using spatial Principal Components Analysis (PCA) to identify a set of orthogonal scalp distributions, “virtual electrodes” that account for the spatial variance. The data were then expressed as ERPs measured at each of the virtual electrodes. These ERPs were analyzed using temporal PCA, yielding a set of “virtual epochs.” Most of the temporal variance of the rare events was associated with a virtual electrode with a posterior topography, that is, with a classical P300, which was active during the virtual epoch associated with the P300. The novel stimuli were found to elicit both a classical P300 and a component focused on a virtual electrode with a frontal topography. We propose that the term Novelty P3 should be restricted to this frontal component.

William James famously described the infant's perceptual world as a “blooming, buzzing confusion,” and a century later, the same words might apply to the field of psychology. With historical roots in both physiology and philosophy, psychology has proliferated into a multitude of subdisciplines served by specialized journals and conferences. In the face of such diversity, a few conferences and publications hold fast to the goal of presenting psychological research across the broad spectrum of subdisciplines. This edited volume, together with its companion volume (Vol. 1: Social, Personal, and Cultural Aspects), represents the proceedings of the XXVIth International Congress of Psychology, convened in Montreal in 1996, with the goal of providing “the latest research developments in psychology from around the world.” The volume contains quality reviews by an international roster of authors, and demonstrates at once both the sophisticated “blooming and buzzing” of many individual research programs in cognitive and biological psychology, and a largely untapped potential for the development of unifying themes and principles across the discipline.

The Society for Psychophysiological Research is pleased to announce Mark W. Miller of Florida State University as the recipient of the 1998 Tursky Award for excellence in predoctoral research. His presentation was selected from all submissions listing pre-doctoral students as senior author at the 38th Annual SPR Meeting in Denver, Colorado. His award-winning presentation, entitled “Startle reflex and reaction time examination of the anxious individual's response to threat,” was coauthored by Christopher J. Patrick.