Visual change detection: event-related potentials are dependent on stimulus location in humans

Infrequent colored patterns within sequences of patterns of frequent color elicited a posterior negative event-related potential component only in case of lower half-field stimulation. This negativity in the 140-200 ms latency range is considered as a correlate of automatic visual change detection (visual mismatch negativity, vMMN). Retinotopic prestriate visual areas are suggested to be the generating loci of vMMN.     

Effects of stimulus change on the electrodermal orienting response

This experiment (N = 48) examined recovery of the skin conductance response, following habituation training, to change in type of visual stimulus. Maher and Furedy (1979) have argued that the majority of such studies have not controlled for time, trial, or stimulus-specific effects. These variables were controlled in the present study by using no-change control groups and by counterbalancing training and test stimuli. Experimental groups received either shapes during training and a letter on the test trial (trial 41) or letters during draining and a shape on the test trial; control groups received either shapes or letters for 41 trials. Test trial response magnitude was larger in experimental than control groups, and the effect was independent of the nature of the test stimulus. In addition, responsiveness increased from the last block of training trials to the test trial for experimental groups, but not for control groups. These results demonstrate recovery of the skin conductance response to change per se.     

Visual search for biological motion: an event-related potential study

To investigate the neural response to detection of biological motion (BM) surrounded by distractors, event-related potentials (ERPs) were recorded. Scrambled motion with the same velocity vector as the BM but randomized initial starting points was used as the distractor. The number of distractors was varied to control the difficulty of the task. The behavioral data showed that the reaction time increased with the number of distractors. Moreover, the ERP results showed that enhanced negativity was elicited at posterior electrodes contralateral to the location of the BM as with the conventional N2pc-like component, which is related to selection of the target. The increment of reaction time indicated that the attentional process is involved in the detection of BM. Furthermore, the ERP waveforms suggest that, even when detection of the target requires form-from-motion processing, similar neural mechanisms to those involved in conventional visual search tasks were employed here.     

Effects of stimulus preexposure and intermodality change on electrodermal orienting

Previous research has indicated that an intermodality change trial presented after a habituation series elicits larger orienting responses than does the first stimulus of that series. Experiment 1 (N= 48) investigated whether this effect was still present if the change stimulus was not novel but was presented once prior to the habituation series. Two groups of subjects were presented with a series of 24 tones or vibrotactile stimuli. Trial 25 was an intermodality change test trial for half of the subjects in each group (change), whereas the remaining subjects received an additional habituation stimulus (no change). Prior to the habituation trials, each subject was exposed once to the test stimulus used in the change condition. Although response magnitude on the test trial was larger in the change condition than in the no-change condition, test trial response magnitude did not exceed that on the first trial of the habituation series. In Experiment 2 (N= 84), one group was preexposed to the test stimulus, another was preexposed to an experimentally irrelevant stimulus, and a third received no stimulus prior to habituation training. Test trial response magnitude was larger than responses to the first stimulus of habituation in the change group that was not exposed to a stimulus prior to habituation but not in the preexposed groups. Preexposure to a stimulus prior to habituation training abolished the intermodality change effect even when the test stimulus was novel. The present results pose problems for noncomparator theories of habituation and support the notion that anticipatory processes are important in orienting and habituation.     

Effects of stimulus repetitions on the event-related potential of humans and rats.

The present study compared the effects of repeated stimulus presentations on the event-related potential (ERP) of humans and rats. Both species were presented with a total of 100 auditory stimuli, divided into four blocks of 25 stimuli. By means of wavelet denoising, single-trial ERPs were established in both humans and rats. The auditory ERPs were characterized by the presence of two positive and two negative waves in both humans and rats, albeit with different latencies in the two species (P1, N1, P2, and N2). The results showed decreased amplitudes within blocks for the N1, P2, and N2 components in humans and for the N1 and P2 components in rats. Decreased amplitudes across blocks were found for the N2 component in humans and for the P2 and N2 components in rats. In both humans and rats, response decrements within a block were thus most prominent for the early ERP components, whereas the changes across blocks were most prominent for the later components. These results suggest a correspondence of the ERP correlates of elemental stimulus processing between humans and rats. It is further suggested that the observed amplitude reductions may reflect habituation and/or recovery cycle processes.     

Effects of cigarette smoking on electrodermal orienting reflexes to stimulus change and stimulus significance

Skin conductance responses (SCRs) evoked by novel, signal, and frequent tone stimuli were measured in 20 male heavy smokers and 10 male nonsmokers over two sessions. All smokers abstained from smoking for 12 hr prior to each session. Half of the smokers smoked a cigarette of their preferred brand prior to SCR measurement in the first session, whereas the remaining smokers smoked in the second session. Nonsmokers did not smoke. Results combined across the two sessions indicated that abstinence was associated with selective depression of SCRs to the novel tone. Separate analyses of results from each session revealed that, in the second session, SCRs to both novel and signal tones were depressed in abstinent smokers, partially replicating previous findings. By contrast, first session results showed no significant effects of smoking or abstinence. Results were interpreted in terms of nicotine's effects on nonspecific arousal, with some reservations.     

Neural mechanisms underlying the orienting response to subject's own name: an event-related potential study

Neural processes underlying the orienting response (OR) to subject's own name (SON) were investigated using the oddball paradigm. Subjects were presented with SON, subject's parent's name, and unfamiliar persons' names while they played a video game and ignored the auditory stimuli. A P3a‐like frontal positivity (P440, 440 ms) indexing OR was elicited by SON only when it was the rare stimulus and its amplitude decreased with the repeated presentation of SON. Preceding the P440, SON consistently elicited an early frontal negativity (SON negativity, 170–270 ms), including when SON was the high‐probability stimulus, and unlike the P440, this negativity did not habituate. These results conform to the hypothesis that early preattentive processing of speech sounds distinguishes SON from other names irrespective of short‐term stimulus context, and that this culminates in an OR only when SON is evaluated as being contextually meaningful.     

Independent manipulation of stimulus change and unexpectedness dissociates indices of the orienting response

Results obtained with the standard repetition-change paradigm of orienting research cannot be attributed unambiguously to either stimulus change or to unexpectedness. By adding announcement conditions, in which participants were told about an impending stimulus change, these two factors were disentangled. In Experiment 1, reaction times (RTs) were longer and ratings of surprise were higher with unannounced than with announced stimulus change. In contrast, larger skin conductance response (SCR) magnitudes occurred following change, irrespective of its congruence with participants' expectations. Experiment 2 replicated the results for SCR magnitude and, furthermore, revealed the same pattern of results for the evoked cardiac response. Surprise ratings again reflected the unexpectedness of stimulus presentations. The dissociation between RT and autonomic measures provides difficulties for resource allocation accounts of the orienting response.     

The orienting response and stimulus significance: some comments.

Bernstein (1969, 1979) has argued that Skolov's (1963) model is not sufficient to account for the data concerning orienting response (OR) elicitation to stimulus change. He has argued that following the registration of stimulus mismatch, an additional stage of stimulus evaluation occurs and that only stimuli which represent change and are judged as 'significant' elicit ORs. The present paper takes issue with this assertion. It is argued that the data on which the 'significance hypothesis' was originally based are not replicable and that the argument, as it was formulated originally, is tautological. It is also argued that individual differences in OR responsiveness are more parsimoniously explained in terms of individual response stereotypy and that differential responsiveness to different sorts of stimulus change poses problems for the significance hypothesis. Evidence is also reviewed which suggests that the relationship between stimulus change and stimulus significance is additive rather than multiplicative as suggested by Bernstein, i.e., stimulus change and stimulus significance are each sufficient for OR elicitation. Finally, it is concluded that the concept of 'significance', introduced operationally, may be of value in terms of examining the role of the OR in information processing.     

An orienting reflex perspective on anteriorisation of the P3 of the event-related potential

In the Go/NoGo task, the P3 component of the event-related potential elicited by NoGo stimuli is topographically anterior to that from Go stimuli. This anteriorisation has been linked to the response inhibition thought to be required when NoGo stimuli are presented, and suggested as an index of inhibition. We report a preliminary investigation of this question from an orienting reflex (OR) perspective, in which the autonomic skin conductance response (SCR) was used as an OR “yardstick”. We presented subjects with a random mix of 15 target and 15 non-target auditory stimuli with a short inter-stimulus interval, and explored the sources of the resultant P3s using low-resolution electromagnetic tomography (LORETA). Across-subject mean SCRs showed exponential decrement over trials and a larger response to targets, as expected from the OR perspective. LORETA analysis of the across-subject mean initial P3s showed exponential response decrement of their common sources, suggestive of the Novelty P3. Grand mean P3s to targets and non-targets appeared to correspond to the P3b and P3a, respectively. These results suggest that anteriorisation of the P3 to NoGo stimuli may reflect processing related to the basic involuntary OR to indifferent (non-significant) stimuli rather than an active inhibitory process.     

幼儿视觉 ERP: Ⅲ.P_3 波面积的研究

以往事件相关电位（ＥＲＰ）研究主要对峰波幅和峰潜伏期进行测量，本研究用人像照片按一定概率编排成刺激序列，成功诱发幼儿ＥＲＰ，并在此基础上对Ｐ３面积进行了测量。结果证明，低概率非靶刺激在幼儿可以诱发出Ｐ３，与任务Ｐ３相比波面积小，提示幼儿Ｐ３波面积有明显的任务效应，再认熟悉人的Ｐ３面积大于再认陌生人，波面积比波幅更合理地反映场合修正量。幼儿在高度选择注意时，Ｐ３面积大。幼儿Ｐ３波面积以Ｐｚ、Ｏｚ电极所描记的为大。     

Habituation of early and late visual ERP components and the orienting reaction: the effect of stimulus information

Single trial event-related potentials at Fz, Cz, Pz and Oz were measured concurrently with pupil reactions and skin conductance reactions in a habituation paradigm. One group of subjects (n = 16) was given 36 simple visual stimuli and a second group (n = 16) 36 complex visual stimuli of equal duration, brightness and dimensions. No task-relevance was given to the stimuli. Under these circumstances we found rapid habituation (within 6 trials) of the vertex N1. Because we used long, variable interstimulus intervals, the N1 decrease could not be explained by refractory effects. Habituation rates of N1 and the concurrently measured SCR did not differ. Although the P3 showed significant habituation over the 12 trials (except at Oz), it habituated slower than the N1 and the SCR. The complex stimulus condition elicited larger P3b waves. No effect of stimulus complexity was found on the N1 and the SCR. The relevance of these results for the OR is discussed.     

The time course of spatial orienting elicited by central and peripheral cues: evidence from event-related brain potentials

To study differences in the time course of attentional orienting triggered by salient peripheral events and by central symbolic precues, event-related brain potentials (ERPs) were recorded in response to letter stimuli following spatially informative symbolic or peripheral precues after a cue-target interval (CTI) of either 200 or 700 ms. Stimuli at cued (attended) locations elicited an enhanced negativity relative to stimuli at uncued locations. With short CTIs, these effects started around 150 ms post-stimulus for peripheral cues. They were delayed by about 100 ms for central cues. This latency difference is assumed to reflect fast exogenous orienting elicited by peripheral, but not by central cues. Beyond 200 ms post-stimulus, attentional negativities were larger with long CTIs than with short CTIs for both cue types, presumably related to the gradual build-up of endogenous orienting triggered by spatially predictive events.     

Event-related potential assessment of attention and the orienting reaction in boxers before and after a fight

Boxers' attention and orienting mechanisms were investigated using event-related brain potential recordings, before and after a fight. This study did not reveal any abnormalities of attention or detection processes. However, a slight deficit in the orienting reaction towards stimuli delivered in the right ear, related to a greater number of blows delivered on the left side of the head, was observed.     

Distinctive conflict processes associated with different stimulus presentation patterns: an event-related potential study

Twelve subjects were asked to perform visual stimulus presentation tasks. Two figures were presented either simultaneously or sequentially. They were either in congruity (same shapes) or in conflict (different shapes) with each other. Conflicting stimulus pairs presented sequentially evoked a negative event-related component with a fronto–central and bilateral posterior scalp distribution, referred to as N270. In contrast, stimuli displayed simultaneously elicited a N220 with fronto–central prominence, irrespective of whether they were in conflict or in congruity. The results suggest that the N270 may be associated with the processing of a conflict with working memory information whereas the N220 might reflect the detection and evaluation of attention to visual information in the human brain.     

Single-trial event-related potentials and autonomic measures of the orienting reflex

We aimed to clarify the event-related potentials (ERPs) associated with elicitation and habituation of the basic Orienting Reflex (OR). Participants were presented with 16 innocuous tones, alternating in intensity, at long variable inter-stimulus intervals, with no task. This allowed us to examine stimulus novelty and intensity effects in the absence of stimulus-related task demands. Single-trial ERPs were extracted to obtain estimates of the early N1 and the late positive complex (LPC) to each stimulus. Electrodermal responses showed substantial main effects of trials and intensity, supporting their functionality as an OR index. Cardiac deceleration showed no systematic change with intensity or trials, suggesting that it marks the transient onset of each stimulus, early in the stimulus-processing sequence. Respiratory pause showed a substantial main effect of trials but no intensity effect, suggesting that it reflects an intermediate processing stage. A main effect of intensity, but no simple trial effect, was apparent in the N1, suggesting that it reflects a different intermediate processing stage. The subsequent LPC showed only a topographic interaction with trials and intensity, failing to support any substantive role in OR processing. These different stimulus-response profiles are discussed in the context of a sequential processing model of the OR.     

Auditory and visual semantic priming using different stimulus onset asynchronies: An event-related brain potential study

Semantic priming effects (behavioral and electrophysiological) were compared in the visual and auditory modalities across three stimulus onset asynchronies (SOAs; 0, 200, and 800 ms). When both prime and target were presented in the visual modality (the prime just to the left of a fixation point and the target to the right) there were N400 priming effects present across the three SOAs. However, the N400 in the 0-ms SOA condition extended longer in time (800 vs. 500 ms) than in the other SOAs. When both the prime and target were presented in the auditory modality (the prime to the right ear and the target to the left), the largest priming effects were found for the 800-ms SOA. Moreover, there was a relatively early priming effect present in the 0- and 800-ms SOA conditions but not in the 200-ms condition. The results are discussed in terms of modality differences in the time course of word comprehension processes.     

Sodium fluoride--a stimulus for a calcium-triggered secretory process.

Calcium triggers the secretion of histamine from mast cells after previous exposure of the cells to sodium fluoride. The secretory process can be divided into a fluoride-activating step and a calcium-induced secretory step dependent on cellular metabolic energy. The secretory response induced by compound 48/80 in the absence of extracellular calcium was found to decrease after fluoride pretreatment of the cells. The response was, however, unaffected, provided calcium was introduced to the cells simultaneously with compound 48/80.     

How a co-actor's task affects monitoring of own errors: evidence from a social event-related potential study

Efficient flexible behavior requires continuous monitoring of performance for possible deviations from the intended goal of an action. This also holds for joint action. When jointly performing a task, one needs to not only know the other??s goals and intentions but also generate behavioral adjustments that are dependent on the other person??s task. Previous studies have shown that in joint action people not only represent their own task but also the task of their co-actor. The current study investigated whether these so-called shared representations affect error monitoring as reflected in the response-locked error-related negativity (Ne/ERN) following own errors. Sixteen pairs of participants performed a social go/no-go task, while EEG and behavioral data were obtained. Responses were compatible or incompatible relative to the go/no-go action of the co-actor. Erroneous responses on no-go stimuli were examined. The results demonstrated increased Ne/ERN amplitudes and longer reaction times following errors on compatible compared to incompatible no-go stimuli. Thus, Ne/ERNs were larger after errors on trials that did not require a response from the co-actor either compared to errors on trials that did require a response from the co-actor. As the task of the other person is the only difference between these two types of errors, these findings show that people also represent their co-actor??s task during error monitoring in joint action. An extension of existing models on performance monitoring in individual action is put forward to explain the current findings in joint action. Importantly, we propose that inclusion of a co-actor??s task in performance monitoring may facilitate adaptive behavior in social interactions enabling fast anticipatory and corrective actions.     

The influence of task relevance and stimulus information on habituation of the visual and the skin conductance orienting reaction

This study investigated the hypothesis that task-relevant stimuli induce orienting reactions (ORs) that are stronger and more resistant to habituation when their information content is high than when it is low. Task-relevance was given to the stimuli by rewarding the subjects for correct recognition at the end of the experiment. The dependent variables in this study were the visual orienting reaction (VOR), the skin conductance reaction (SCR), their habituation scores and the number of spontaneous fluctuations in skin conductance (SFs). 28 subjects received two blocks of 14 trials. Half the subjects received the higher information condition first and then the lower information condition, while the other half received the reversed order. The VOR habituated quickly and was not significantly influenced by information value. SCR amplitudes were larger and SCR-habituation slower to stimuli containing more information. The results were interpreted as supporting the hypothesis that the SCR is associated with a secondary phase of the orienting process.