A variety of processes contribute to successful recognition memory, some of which can be associated with spatiotemporally distinct event-related potential old/new effects. An early frontal and a subsequent parietal old/new effect are correlated with the familiarity and recollection subcomponents of recognition memory, respectively, whereas a late, postretrieval old/new effect seems to reflect an ensemble of evaluation processes that are set by the task context in which retrieval occurs. Both the early frontal and the parietal old/new effects are differentially modulated by the informational content (e.g., object forms and spatial locations) of recognition and seem to rely on brain systems damaged in amnesia. The late frontal effect appears to reflect prefrontal cortex activation. A neurophysiologically based model of recognition memory retrieval is presented and it is shown that coupling recognition memory subprocesses with distinct old/new effects allow examination of the time course of the processes that contribute to correct and to illusory memories. In conjunction with event-related functional magnetic resonance imaging activation patterns the brain systems recruited by various aspects of episodic memory retrieval can be identified.

Effects of nicotine and caffeine, separately and in combination, were assessed in 12 male habitual smokers in a repeated-measures design. Caffeine (0-mg vs. two 150-mg doses administered in a decaffeinated/sugar-free cola drink post-baseline and 90 min later) was crossed with nicotine (ad libitum own dosing vs. 1.0-mg machine-delivered dose vs. 0.05-mg machine-delivered dose). Participants smoked a total of five cigarettes at 30-min intervals over a 2-hr period. Caffeine and nicotine had large effect sizes on electroencephalogram (EEG) power; however, these effects were modulated by the eyes open versus closed condition, the other drug, and electrode site. EEG effects of open versus closed eyes tended to be of the same size and direction as those of nicotine and caffeine. However, whereas nicotine increased EEG power in some higher frequency bands in some conditions, caffeine decreased EEG power across almost all conditions. Serum cortisol concentration, vigor, and pleasantness were increased by nicotine, but not by caffeine. Level of depressive mood depended on an interaction of caffeine and nicotine. Vigilance performance was enhanced significantly by caffeine and was increased almost significantly by nicotine. The findings were interpreted in terms of common and differential mechanisms of the two drugs.

Although memory has been widely studied using event-related potentials, memory-related changes in the electroencephalogram (EEG) have been relatively neglected. The aim of this study was to determine whether evidence could be found for memory-related changes in the EEG. EEG was recorded from a sample of healthy volunteers while they performed word and face recognition memory tasks. Data were analyzed using the method of event-related desynchronization. In the theta frequency range there was a short-duration increase in power that occurred in the first 250 ms that was maximal at temporal sites (T5/T6). For words, but not faces, there was a repetition effect in theta such that new words elicited greater synchronization than old words at the midline frontal electrode (Fz). In the alpha frequency range there was a lateralized repetition effect, which occurred from 750 ms. In upper alpha this effect was lateralized in the expected way with greater desynchronization at temporo-parietal sites on the left for words and on the right for faces. For lower alpha, the lateralization was reversed. The meanings of these findings are interpreted in the light of existing models of recognition memory.

This study examined the hypothesis that global and selective inhibition are mediated by distinct mechanisms: respectively, a peripheral mechanism, indexed by heart rate slowing, and a central mechanism, indexed by cortical but not autonomic measures. Three varieties of a Go-NoGo task were presented in which the Go signal required an index finger response rapidly followed by a middle finger response. The NoGo signal required the inhibition of (a) both responses (global inhibition), (b) the middle finger response (simple selective inhibition), or (c) the index finger response of one hand and the middle finger response of the other hand (complex selective inhibition). As anticipated, global inhibition was indexed by heart rate slowing. Most importantly, heart rate slowing was also elicited by selective inhibition and was more pronounced for complex than simple selective inhibition. These findings suggest that global and selective inhibition are mediated by one rather than two mechanisms and that heart rate is sensitive to the demands placed on this inhibition mechanism.

The effects of mental fatigue on planning and preparation for future actions were examined, using a task switching paradigm. Fatigue was induced by “time on task,” with subjects performing a switch task continuously for 2 hr. Subjects had to alternate between tasks on every second trial, so that a new task set was required on every second trial. Manipulations of response–stimulus intervals (RSIs) were used to examine whether subjects prepared themselves for the task change. Behavioral measurements, event-related potentials (ERPs), and mood questionnaires were used to assess the effects of mental fatigue. Reaction times (RTs) were faster on trials in which no change in task set was required in comparison with switch trials, requiring a new task set. Long RSIs were used efficiently to prepare for the processing of subsequent stimuli. With increasing mental fatigue, preparation processes seemed to become less adequate and the number of errors increased. A clear poststimulus parietal negativity was observed on repetition trials, which reduced with time on task. This attention-related component was less pronounced in switch trials; instead, ERPs elicited in switch trials showed a clear frontal negativity. This negativity was also diminished by time on task. ERP differences between repetition and switch trials became smaller with increasing time on task.

Heart rate was recorded from five different groups of children (ages 7, 10, 12, 14, and 20 years) while they were performing an auditory selective attention task. The participants were instructed to count rare tone pips embedded in a series of standard tone pips presented at one (attended) ear while ignoring rare and standard stimuli presented at the other (unattended) ear. A pattern of anticipatory heart rate deceleration followed by acceleration was associated with rare tone pips at the attended ear but not with rare tone pips that should be ignored. The absence of differential sensitivity of heart rate responses to rare tone pips presented at the unattended ear was observed for all age groups. These findings were interpreted to suggest that the ability to ignore irrelevant target stimuli has reached mature levels during middle childhood. The depth of anticipatory deceleration increased until age 14, suggesting that the ability to maintain attentional set continues to develop beyond childhood.

The mechanism underlying acute changes in secretory immunoglobulin A (sIgA) remains to be determined. In this experiment, sIgA and cardiovascular activity were monitored at rest and while participants performed a mental arithmetic task, cold pressor, and submaximal cycle exercise following placebo or 1 mg of the alpha-adrenergic blocker, doxazosin. Under placebo, the tasks produced patterns of cardiovascular activity indicative of combined alpha- and beta-adrenergic, alpha-adrenergic, and beta-adrenergic activation, respectively. Doxazosin was associated with reduced blood pressure during cold pressor, but not during arithmetic or exercise. Mental arithmetic elicited increases in sIgA concentration and exercise produced increases in both sIgA concentration and secretion rate; these changes were unaffected by alpha blockade. In contrast, the cold pressor was associated with decreases in both sIgA concentration and secretion rate, which were blocked by doxazosin. These data suggest that acute decreases, but not increases, in sIgA are mediated by alpha-adrenergic mechanisms.

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.

According to A.H.C. Van der Heijden (1992), attentional selection of visual stimuli can be considered as location selection. Depending on the type of task, location selection can be considered to be automatic (e.g., in case of abrupt onsets), directly controlled (e.g., in case of symbolic precues), or indirectly controlled (e.g., in case of visual search). In tasks with symbolic precues a contralateral enhancement of the P1 event-related potential (ERP) component has been found, whereas in visual search tasks a contralateral enhancement of the N2 component has been found. We hypothesized that both lateralized effects reflect the influence of location selection, which differs only in its moment of activation. Linear arrays (a target among five distractors, presented at two eccentricities) requiring left or right responses, were preceded by cues indicating either the precise target location or the side of the target, or by bilateral cues that indicated all array positions. Array-evoked ERPs, corrected for cue-evoked and interactive effects, showed not only lateralized but also target location-specific effects for both components, which supports the view that, depending on the type of task, either the P1 or the N2 component reflect the influence of location selection.

Twenty-eight volunteers were instructed to attend stimuli presented at one side of the computer screen and to ignore stimuli presented at the other side. Both attended and unattended stimulus series consisted of targets (25%) and nontargets (75%) defined on the basis of stimulus shape. Attended targets required a binary choice based on stimulus color. Selective attention led to the expected increase in both midlatency (N2b) and late (P3) brain potential components. Furthermore, selective attention led to increased anticipatory cardiac slowing preceding the target stimulus and to increased primary bradycardia. Correlational analyses revealed a positive relation between the effects of selective attention on N2b amplitude and primary bradycardia suggestive of cortical involvement in the chronotropic control of heart rate.

The present study used the picture perception paradigm to examine the extent to which three well-documented psychophysiological measures demonstrate consistency across time in response to emotional stimuli. The three measures were the eye-blink startle response and the activation in two facial muscle regions (zygomatic and corrugator). Twenty-seven young women were assessed on two occasions, 2 weeks apart. Whereas activation in the corrugator and zygomatic muscle regions demonstrated the predicted patterns at both assessments (with some attenuation in the zygomatic muscle regions), the startle response had limited consistency across the two assessments. The startle response revealed the predicted linear pattern of valence modulation during the first assessment. During the second assessment, startle magnitude response was a quadratic function of valence ratings and a linear function of arousal ratings. The unexpected pattern of startle response during the second session appeared to be related to the content of the pleasant slides, with action slides generating quadratic valence modulation and erotic slides continuing to exhibit the expected linear valence modulation.

Previous research on asymmetric effects of emotional expression and brain-hemispheric asymmetry has supported opposing theories of hemispheric dominance in the control of emotional reactions. In the present study, 32 subjects were exposed to pictures of happy and angry facial stimuli while facial electromyographic (EMG) activity from the zygomatic major and the corrugator supercilii muscle regions was detected from the left and right sides of the face. The subjects reacted spontaneously and rapidly with larger zygomatic EMG activity to happy facial stimuli and larger corrugator EMG activity to angry stimuli. These distinct reactions were significantly larger on the left side of the face. It is concluded that the present results support the hypothesis that the right brain hemisphere is predominantly involved in the control of spontaneously evoked emotional reactions.

Event-related potential (ERP) evidence for the existence of cross-modal links in endogenous spatial attention between vision and touch was obtained in an experiment where participants had to detect tactile or visual targets on the attended side and to ignore the irrelevant modality and stimuli on the unattended side. For visual ERPs, attentional modulations of occipital P1 and N1 components were present when attention was directed both within vision and within touch, indicating that links in spatial attention from touch to vision can affect early stages of visual processing. For somatosensory ERPs, attentional negativities starting around 140 ms poststimulus were present at midline and lateral central electrodes when touch was relevant. No attentional somatosensory ERP modulations were present when vision was relevant and tactile stimuli could be entirely ignored. However, in another task condition where responses were also required to infrequent tactile targets regardless of their location, visual-spatial attention modulated somatosensory ERPs. Unlike vision, touch apparently can be decoupled from attentional orienting within another modality unless it is potentially relevant.

In two previous experiments, we studied how stimulus motion affects both the self-report of emotion experience and the physiological sequelae of emotion. In both studies, image motion intensified emotional responding, and the effect of motion was relatively specific to the arousal dimension of the emotion; there was little evidence that image motion altered the valence of the image. Moving images also appeared to sustain the attention of the participants for a longer period of time than did the still images. In these two experiments, however, image motion was manipulated within participants. In the present experiment, we used a between-subjects manipulation of image motion and found a nearly identical pattern of results. These data indicate that motion inherently increments the arousal value of an image and that this increment is not dependent on the context in which motion is introduced.

Attentional and information processing impairments have been evidenced in nonclinical anhedonic subjects. However, the extent of attentional deficit has not been determined. We studied focused attention, the ability to reject irrelevant or distracting messages, in anhedonic nonclinical subjects. The event-related potentials and behavioral performances of anhedonic subjects were compared with those of control subjects during the Eriksen focused attention task (C.W. Eriksen & B.A. Eriksen, 1974); the task combined one compatible and one incompatible condition, the latter causing an interference. Anhedonic subjects exhibited a smaller P300 and slower reaction times than control subjects. Varying task conditions had different effects on anhedonic subjects and controls, suggesting that anhedonic subjects may have developed a conservative response strategy. In view of previous works, these results suggest that attentional impairment is not ascribed to specific processes, but may involve a more global deficit, that is, a resource allocation deficit.