Methodological issues in event-related brain potential research

Event-related brain potential (ERP) measures have become increasingly popular in experimental psychology and are often employed by researchers who are not formally trained in electrophysiology. A proper application of these measures requires knowledge about the methodological principles and practical issues that are relevant to ERP measurement, analysis, and interpretation. A brief introductory survey of different aspects of ERP methodology (recording, data processing and signal extraction, statistical analysis and interpretation of ERP effects) is presented, and the contributions collected in this special issue on ERP methodology are introduced.     

The lateralized readiness potential as an on-line measure of central response activation processes

The lateralized readiness potential (LRP) is an electrophysiological indicator of the central activation of motor responses. Procedures for deriving the LRP on the basis of event-related brain potential (ERP) waveforms obtained over the left and right motor cortices are described, and some findings are summarized that show that the LRP is likely to reflect activation processes within the motor cortex. Two experiments investigating spatial S-R compatibility effects are reported that demonstrate that, because of systematic overlaps of motor and nonmotor asymmetries, LRP waveforms derived by the double subtraction method cannot always be interpreted unequivocally in terms of response activation. Such confounds can be detected when LRP waveforms are compared with difference waveforms obtained by the double subtraction method from ERPs elicited at other lateral scalp sites.     

What is improved if a mental rotation task is repeated – the efficiency of memory access, or the speed of a transformation routine?

The present study contrasts 3 theories which provide explanations for performance improvement in mental rotation tasks. Wallace and Hofelich conjectured that the process as such may be executed more rapidly after training, while Bethell-Fox and Shepard attributed practice effects to the fact that images may be transformed first elementwise, but later as a Gestalt. In contrast, Tarr and Pinker assumed that a transformation of an image will no longer be computed after training but simply be retrieved from memory. Thirty-seven subjects participated in 3 test sessions in which they had to decide on the parity of 3-D block figures presented from different perspectives. Experimental group subjects underwent 4 additional practice sessions in which a subset of the figures and a subset of perspective views were used. Tests adapted to the predictions of the 3 theories revealed specific learning effects but no transfer, neither to old objects presented in new perspectives nor to new objects. This supports an instance-based explanation of practice effects which states that objects are represented in multiple perspective views. Received: 7 May 1997 / Accepted: 6 August 1997     

In defense of psychological laws

It is argued that psychological explanations involve psychological generalizations that exhibit the same features as laws of physics. On the basis of the “systematic theory of lawhood”, characteristic features of laws of nature are elaborated. Investigating some examples of explanations taken from cognitive psychology shows that these features can also be identified in psychological generalizations. Particular attention is devoted to the notion of “ccteris‐paribus laws”. It is argued that laws of psychology are indeed ceteris‐paribus laws. However, this feature does not distinguish them from the laws of physics, because such laws are found in physics as well. Moreover, the laws invoked in psychological explanations are genuine laws of psychology; they are not laws of other disciplines that are brought to bear on psychological problems. The conclusion is that if there are laws of physics then laws of psychology exist as well.     

Inconsistencies in extensive games

In certain finite extensive games with perfect information, Cristina Bicchieri (1989) derives a logical contradiction from the assumptions that players are rational and that they have common knowledge of the theory of the game. She argues that this may account for play outside the Nash equilibrium. She also claims that no inconsistency arises if the players have the minimal beliefs necessary to perform backward induction. We here show that another contradiction can be derived even with minimal beliefs, so there is no paradox of common knowledge specifically. These inconsistencies do not make play outside Nash equilibrium plausible, but rather indicate that the epistemic specification must incorporate a system for belief revision. Whether rationality is common knowledge is not the issue.     

Serial learning: Identification of subjective subsequences

Learning of fixed arbitrary sequences proceeds by idiosyncratic subsequencing and assembly of the resulting subsequences. An error item that just precedes a subjective subsequence is a closely constrained member of that subsequence. Identification and characterization of subjective subsequences were accomplished by analyses of forward serial learning, free recall, and backward serial learning. We conclude that ordinary serial learning cannot be represented by traditional continuous-process theories, but instead must be treated by an organizational model.     

Victims of violence: Psychological effects and aftereffects

The American Journal of Psychoanalysis -     

Reconstruction of arbitrary versus logical sequences by preschool children

The ability of preschool children to construct and reconstruct ordered sequences was examined in a series of four experiments. In Expt. 1, the task was to copy, with the model present or absent, the order of items pegged on a clothesline. In Expts. 2–4, the subjects were required to reconstruct ordered series of pictures from memory. In all experiments, the orders were either logical or arbitrary. Reconstruction of an arbitrary series of events is within the problem solving capacity of 4-yr-old children if (a) reconstruction takes place in the presence of the model or follows immediately upon the removal of the model and (b) the original sequence is presented simultaneously. If, however, the lag between viewing and reconstruction is increased and/or the original set is not viewed simultaneously, as a unit, performance declines. The provision of an inherent order to the items within a set, either by introducing a connective narrative, or a depicted logical sequence, is sufficient to maintain that order over time and to provide a unifying cohesion to the items when viewed successively.     

False physiological feedback and persuasion: Effect of fear arousal vs. fear reduction on attitude change

Two experiments tested the hypothesis that increases in false physiological feedback of fear arousal will enhance persuasion and that reduction in the arousal feedback is unnecessary for increased persuasion to occur. Prior research has usually found a positive relation between level of arousal and persuasion, but support for the drive reduction hypothesis is tenuous. However, Harris and Jellison (1971) claimed support for such a hypothesis. They manipulated subjects' fear arousal cognitively via false physiological feedback while the subjects listened to a persuasive communication. The present experiments used a similar procedure in an attempt to test an "arousal only" against an "arousal reduction" hypothesis. Subjects listened to a persuasive speech while receiving false feedback via a meter concerning their fear arousal. In Experiment I half of the subjects received high arousal and half received moderate arousal information. Within each of these conditions half of the subjects had their arousal reduced, and the other half did not. In Experiment II subjects received either low arousal, high arousal, or high then low arousal feedback while listening. The results of the two studies generally provided support for the "arousal only" hypothesis. An interpretation in terms of Bem's attribution theory was tentatively suggested.