Pre- and poststimulus activation of response channels: a psychophysiological analysis

To examine mechanisms of response activation, we asked subjects to respond differentially to the central letter of one of four arrays--HHHHH, SSHSS, SSSSS, and HHSHH--and measured event-related brain potentials (ERPs) and electromyographic activity (EMG). For very fast responses, accuracy was at chance level for all arrays, suggesting that subjects were guessing. For intermediate latency responses, accuracy was above chance if the noise was compatible with the targets and below chance if it was incompatible, suggesting that these responses were based on partial stimulus analysis. For slow responses, accuracy was above chance for all arrays, suggesting that these responses were based on complete stimulus analysis. The occurrence and accuracy of fast responses could be predicted by examining motor potentials preceding the presentation of the array. Measures of the motor potentials in the period following the presentation of the array suggested that partial analysis of stimulus information could activate responses and that the level of response activation at the time of the EMG response was constant for trials with different response latencies. The data are discussed in terms of a response channel conception.     

A laboratory task for induction of mood states

One hundred female college students were administered the Harvard Group Scale of Hypnotic Susceptibility, Form A, to provide a measure of primary suggestibility. In a 2nd hr, each S was randomly assigned to one of five individual treatments of 20 Ss each. One group read and concentrated upon 60 self-referent statements intended to be elating: a second group read 60 statements intended to be depressing. A third group read 60 statements which were neither self-referent nor pertaining to mood. This group controlled for the effects of reading and experimental participation per se. Fourth and fifth groups received demand characteristics control treatments designed to produce simulated elation and simulated depression, respectively.

Two measures of pre-treatment mood level were obtained from each S at the beginning other individual treatment. Following treatment, as criteria for elation and depression, seven behavioral task measures were obtained. Four of these distinguished significantly among the treatment groups. The comparative performance of Ss in the three control groups indicated that the obtained mood changes could not be attributed to artifactual effects. Moreover, post-experimental questionnaire data strongly supported the conclusion that Elation and Depression treatments had indeed respectively induced elation and depression.     

A psychophysiological study on the function of the response‐stop in the Eriksen task1,2

Abstract: In the Eriksen task, we examined the hypothesis ( Iwaki, 1998 ) that a negative event‐related potential, which was enlarged at the frontal site synchronized with the presentation of an erroneous response causing stimulus, is related to the response‐stop function. Fourteen subjects responded selectively with their hands to the stimuli that consisted of a central target letter and surrounding compatible noise letters (e.g., HHHHH) or incompatible noise (e.g., SHHHS for small‐conflict condition or SSHSS for large‐conflict). The results showed that the increased negativity for the incompatible stimuli was synchronized with the stimulus onset but not with the response. Based on the hypothesis above, it is predicted that greater enhancement of an erroneous response by a stimulus causes the response‐stop to work harder in order to avoid an error, and this results in the larger negativity. This was supported by the evidence showing that the negativity was largest for the large‐conflict incompatible stimulus, followed by the small‐conflict, and then the compatible. We also discuss the possibility that the negativity is the NO‐GO potential concerned with the response‐stop function.     

Exogenous influences on task set activation in task switching

To explore the effect of exogenous processes on cognitive control, we used a cueing task-switching paradigm with two spatial judgement tasks and added an irrelevant colour attribute to the task-relevant spatial attribute of the target. The colour was not related to any specific Stimulus–Response relation in the tasks. A correlation was created between stimulus colour and task identity. This correlation was strong but imperfect in Experiment 1 and perfect in Experiment 2. As a result of the colour–task correlation, stimuli contained redundant information about task identity. By changing the correlation pattern every few blocks we caused this information to be sometimes invalid. In both experiments, performance was worse when the information carried by the target was invalid than when it was valid. However, this effect was exclusive to conditions with short task preparation time. By comparing performance with a control group, which had no colour–task correlation (in Experiment 2) we established that the colour manipulation did not cause a qualitative change in preparation strategy, and that the exogenous effect was stronger in switch trials than in repetition trials. We conclude that exogenous processes that are related to task set affect performance primarily if they are presented before endogenous processes of task set preparation have been launched.     

Exogenous influences on task set activation in task switching

To explore the effect of exogenous processes on cognitive control, we used a cueing task-switching paradigm with two spatial judgement tasks and added an irrelevant colour attribute to the task-relevant spatial attribute of the target. The colour was not related to any specific Stimulus-Response relation in the tasks. A correlation was created between stimulus colour and task identity. This correlation was strong but imperfect in Experiment 1 and perfect in Experiment 2. As a result of the colour-task correlation, stimuli contained redundant information about task identity. By changing the correlation pattern every few blocks we caused this information to be sometimes invalid. In both experiments, performance was worse when the information carried by the target was invalid than when it was valid. However, this effect was exclusive to conditions with short task preparation time. By comparing performance with a control group, which had no colour-task correlation (in Experiment 2) we established that the colour manipulation did not cause a qualitative change in preparation strategy, and that the exogenous effect was stronger in switch trials than in repetition trials. We conclude that exogenous processes that are related to task set affect performance primarily if they are presented before endogenous processes of task set preparation have been launched.     

Unconscious activation of task sets

Using an explicit task cuing paradigm, we tested whether masked cues can trigger task-set activation, which would suggest that unconsciously presented stimuli can impact cognitive control processes. Based on a critical assessment of previous findings on the priming of task-set activation, we present two experiments with a new method to approach this subject. Instead of using a prime, we varied the visibility of the cue. These cues either directly signaled particular tasks in Experiment 1, or certain task transitions (i.e., task repetitions or switches) in Experiment 2. While both masked task and transition cues affected task choice, only task cues affected the speed of task performance. This observation suggests that task-specific stimulus–response rules can be activated only by masked cues that are uniquely associated with a particular task. Taken together, these results demonstrate that unconsciously presented stimuli have the power to activate corresponding task sets.     

Evaluating polygraphy from a psychophysiological perspective: A specific-effects analysis

It is suggested that purportedly scientific positions and technologies are actually spiritualistic or superstitious to the extent that specific effects are not identified and evaluated. This claim is then examined with respect to polygraphy, which appears to have particularly strong spiritualistic tendencies. This technology’s putative basis is the science of psychophysiology, which is the study of psychological processes by means of unobtrusive physiological measures that reflect functions over which there is relatively little voluntary control. The underlying rationale of polygraphy is that information about these functions provided to the examiner has a specific, beneficial effect of improving the detection of deception. Before considering the validity of the polygraph in these specific-effect terms, the paper notes some serious societal problems involved in the use of the polygraph, problems that suggest that polygraphy is appropriately characterized as a serious “social disease.” As to its scientific status, the technique suffers from at least three significant and possibly insurmountable problems: 1) the records are not read “blind”; 2) the method of scoring is subjective, compared to the standards of scientific psychophysiology; and 3) the so-called “control” question method does not involve control in the standard, accepted, scientific sense of that term. However, much of the rest of psychology is also criticised as teleological and spiritualistic, and it is suggested that the polygraph is merely a dramatic illustration of the spiritualist approach that permeates the thought of most researchers in, and practitioners of, the science of psychology.     

The dimensionality of the flanker compatibility effect: A psychophysiological analysis

The psychophysiological approach was used to evaluate the effects of feature similarity and intrinsic response mapping on the flanker compatibility effect. Symbol (e.g., < > < and < / <) and letter arrays (e.g., HCH and SCS) were used. Results showed that delays in stimulus evaluation and both peripheral and central response competition contributed to the compatibility effect, with the contribution of these processes depending on feature similarity and the intrinsic response mapping of the stimuli. For letter stimuli, the difference in the size of the compatibility effect for similar and dissimilar arrays could be accounted for in terms of stimulus evaluation. For symbol arrays, differences in size of the compatibility effect could be accounted for by response competition. Thus, symbol and letter arrays do not appear to be processed differently; what is different is the degree to which stimulus and response-related processes are affected by incompatibility.     

Current task activation predicts general effects of advance preparation in task switching

Two experiments investigated the way that beforehand preparation influences general task execution in reaction-time matching tasks. Response times (RTs) and error rates were measured for switching and nonswitching conditions in a color- and shape-matching task. The task blocks could repeat (task repetition) or alternate (task switch), and the preparation interval (PI) was manipulated within-subjects (Experiment 1) and between-subjects (Experiment 2). The study illustrated a comparable general task performance after a long PI for both experiments, within and between PI madipulations. After a short PI, however, the general task performance increased significantly for the between-subjects manipulation of the PI. Furthermore, both experiments demonstrated an analogous preparation effect for both task switching and task repetitions. Next, a consistent switch cost throughout the whole run of trials and a within-run slowing effect were observed in both experiments. Altogether, the present study implies that the effects of the advance preparation go beyond the first trials and confirms different points of the activation approach (Altmann, 2002) to task switching.     

Type A behaviour and psychophysiological arousal

The "coronary prone" or Type A behaviour pattern, characterized by e.g., hard-driving competitiveness, impatience and aggressiveness, is associated with elevated systolic blood pressure and catecholamine secretion during challenge. In experiments at our laboratory, elevated psychophysiological arousal was found in Type A subjects during understimulation, but not during active performance on a self-paced reaction time task. Results suggest that differences in cardiovascular and behavioural reactivity between Type A and B persons tend to be related to the pace of the environment to which they are exposed. Studies of antecedents of Type A behaviour in children show that "Type A children" respond to challenge with a greater increase in sympathetic arousal than "non-Type As". This suggests the possibility that genetic dispositions and/or conditioned sympathetic reactivity play an important role in the development of the Type A behaviour pattern.     

PSAAL: A LabVIEW 3 program for data acquisition and analysis in psychophysiological experiments

PSAAL (Physiological Signals Acquisition and Analysis in LabVIEW language) is a group of seven programs, written in LabVIEW 3.0 language and specialized for acquisition, analysis, reduction, and display of peripheral and central physiological data. The main characteristics of the programs are the wide range of use for most short-duration psychophysiological paradigms and the easy-to-use graphic interface. In addition, two noteworthy features of LabVIEW are included: the portability of the programs on Macintosh, PowerMac, IBM, HP-UX, and SUN computers, and the capability of handling acquisition on many National Instruments A/D boards, including the low-cost ones. PSAAL performs acquisition and simple reduction of peripheral physiological responses with 12- or 16-bit resolution according to the A/D board used. Analysis includes conversion of electrocardiogram into heart rate, the elaboration of the main parameters of skin conductance responses, electromyogram, startle reflex, and averaging of evoked potentials or other event-related physiological responses, under different experimental conditions. The programs allow the user to perform the organization of the data in a spreadsheet ready for most statistical packages and without the use of other spreadsheet applications.     

Selective response activation can begin before stimulus recognition is complete: a psychophysiological and error analysis of continuous flow

In discussions of process models of human information processing, the continuous flow conception (Eriksen and Schultz 1979) plays a prominent role. A central prediction of this conception is that any information in a display associated with a response activates that response as soon as it becomes available in the perceptual system. If it concerns the correct response channel, then response facilitation occurs. If it concerns the incorrect response channel, then response competition occurs. To assess these mechanisms more directly, we used psychophysiological measures as well as reaction time (RT). We used the latency of the P3 component of the event related brain potential (ERP) as an index of stimulus evaluation duration, the onset of lateralized motor activity derived from the ERP as an index of selective central motor activation, and the onset of electromyographic activity as an index of the start of peripheral motor activation. Subjects were required to respond to target letters that were either flanked by letters that signalled the opposite response (incompatible arrays), by the target itself (compatible arrays), by letters not associated with a response (neutral arrays), or by no other letters (targets alone). Our results replicated the basic findings obtained in this paradigm. RTs to targets alone did not differ from RTs to compatible arrays. The latter were faster than RTs to neutral arrays, which were faster than RTs to incompatible arrays. P3 latencies were longer on incompatible than on neutral trials, and longer on compatible than on target alone trials. Incorrect central response activation on incompatible trials and correct central response activation on compatible trials, both began earlier than on target alone trials. Peripheral responding on both trial types, however, began later than on target alone trials. More incompatible but less compatible trials than neutral ones exhibited incorrect peripheral response activation. Peripheral response execution was faster and more accurate on compatible than on target alone trials, while it was slower and less accurate on incompatible than on neutral trials. These results indicate, that the flankers activated their associated response channel while display evaluation was still going on, and that response facilitation and competition occurred. After applying criteria proposed by Miller (1988), it was concluded that the set of stimulus recognition processes and the set of response activation processes cannot be regarded as independent stages of processing.     

Goal orientation, task difficulty, and task interest: A multilevel analysis

We studied whether goal orientation affects the relationships that task difficulty and interest have with self-set goals. Using a sample of 499 undergraduate students who listed grade goals for their classes, we employed Hierarchical Linear Modeling to explain differences in the extent to which difficulty and interest related to goals. Higher goals were set for more interesting and easier classes, and for individuals higher in mastery goal orientation and for those lower in performance-avoidance orientation (at average levels of interest and difficulty). Furthermore, performance-approach and performance-avoidance orientations reduced and strengthened (respectively) the effects of task difficulty on self-set goals, and the buffering effect of mastery orientation was marginally significant. Portions of this paper were presented at the 19^th Annual Conference of the Society for Industrial and Organizational Psychology, Chicago, IL, in April 2004.     

Automatic activation of task-related representations in task shifting

Stimulus displays consisting of a target and a distractor can produce task conflicts when target and distractor are associated with different tasks. The present study examined whether these stimulus-induced task conflicts are affected by priming the irrelevant task or by increasing the salience of the distractor. In a series of three experiments, we employed a task-shifting paradigm in which subjects had to apply one of two judgments to either the global or the local level of a hierarchical stimulus. In each block, the target level and the judgment were either constant or mixed. Stimulus-induced judgment conflicts were measured by comparing performance for stimuli associated with two judgments and stimuli associated with only one. It turned out that only mixing the target level and not mixing the judgment increased the conflicts. These findings indicate that only the salience of the distractor modulates stimulus-induced conflicts.     

Automatic and intentional activation of task sets.

Four experiments examined automatic and intentional activation of task sets in a switching paradigm. Experiment 1 demonstrated incidental task sequence learning that was not accompanied by verbalizable task sequence knowledge. This learning did not affect task shift cost and may be attributed to automatic task-set activation. In Experiment 2, both shift cost and learning effect increased when the response-cue interval was short, indicating the influence of residual, persisting activation of the preceding task set. In Experiment 3, learning disappeared with a long cue-stimulus interval (CSI), which resulted in a strong preparation effect. This preparation, however, reduced reaction time level but was not specific to task shifts. Finally, Experiment 4 showed that a within-subject C