Sensation seeking and the aversive motivational system

Sensation seeking (SS) has traditionally been viewed as a phenomenon of the appetitive motivational system. The limited SS research exploring contributions from the aversive motivational system reveals greater anxious reactivity to dangerous activities among low sensation seekers. The present study extends this line of work by comparing levels of fear and anxiety during anticipation of predictable and unpredictable aversive stimuli across high- and low-SS groups. Low sensation seekers displayed greater fear-potentiated startle (FPS) to predictable aversive stimuli, and only those low on SS showed FPS and skin conductance response effects during experimental contexts in which aversive stimuli were delivered unpredictably. Findings implicate enhanced apprehensive anticipation among those low on SS as a potential deterrent for their participation in intense and threatening stimulus events.     

Do chickens (Gallus gallus f. domestica) decompose visual figures?

To investigate whether learning to discriminate between visual compound stimuli depends on decomposing them into constituting features, hens were first trained to discriminate four features (red, green, horizontal, vertical) from two dimensions (colour, line orientation). After acquisition, hens were trained with compound stimuli made up from these dimensions in two ways: a separable (line on a coloured background) stimulus and an integral one (coloured line). This compound training included a reversal of reinforcement of only one of the two dimensions (half-reversal). After having achieved the compound stimulus discrimination, a second dimensional training identical to the first was performed. Finally, in the second compound training the other dimension was reversed. Two major results were found: (1) an interaction between the dimension reversed and the type of compound stimulus: in compound training with colour reversal, separable compound stimuli were discriminated worse than integral compounds and vice versa in compound training with line orientation reversed. (2) Performance in the second compound training was worse than in the first one. The first result points to a similar mode of processing for separable and integral compounds, whereas the second result shows that the whole stimulus is psychologically superior to its constituting features. Experiment 2 repeated experiment 1 using line orientation stimuli of reversed line and background brightness. Nevertheless, the results were similar to experiment 1. Results are discussed in the framework of a configural exemplar theory of discrimination that assumes the representation of the whole stimulus situation combined with transfer based on a measure of overall similarity.     

Data quality affects meta-analytic conclusions: a response to Miner and Raju (2004) concerning entrepreneurial risk propensity

J. B. Miner and N. S. Raju (2004) contended that there are additional studies that compare the risk propensity of entrepreneurs and managers, which, when added to the data from W. H. Stewart and P. L. Roth (2001) and meta-analyzed, produce relationships between risk propensity and entrepreneurial status that are substantially weaker than previously believed. This conclusion was evaluated by identifying and examining methodological problems associated with their inclusion of effect sizes (i.e., ds) from studies with variables not relevant to research questions, dependent samples, extraneous variance in outcome variables, and confusion of constructs. When these methodological issues were addressed, a new meta-analysis indicated an overall conclusion consistent with that of Stewart and Roth, but the results varied according to instrumentation, particularly objective instrumentation (observed d = 0.31) versus the Miner Sentence Completion Scale-Form T (observed d = -0.35).     

An integrated theory of the mind

Adaptive control of thought-rational (ACT-R; J. R. Anderson & C. Lebiere, 1998) has evolved into a theory that consists of multiple modules but also explains how these modules are integrated to produce coherent cognition. The perceptual-motor modules, the goal module, and the declarative memory module are presented as examples of specialized systems in ACT-R. These modules are associated with distinct cortical regions. These modules place chunks in buffers where they can be detected by a production system that responds to patterns of information in the buffers. At any point in time, a single production rule is selected to respond to the current pattern. Subsymbolic processes serve to guide the selection of rules to fire as well as the internal operations of some modules. Much of learning involves tuning of these subsymbolic processes. A number of simple and complex empirical examples are described to illustrate how these modules function singly and in concert.     

Holography does not account for goodness: a critique of van der Helm and Leeuwenberg (1996)

P. A. van der Helm and E. L. J. Leeuwenberg (1996) outlined a holographic account of figural goodness of a perceptual stimulus. The theory is mathematically precise and can be applied to a broad spectrum of empirical data. The authors argue, however, that the account is inadequate on both theoretical and empirical grounds. The theoretical difficulties concern the internal consistency of the account and its reliance on unspecified auxiliary assumptions. The account also makes counterintuitive empirical predictions, which do not fit past data or the results of a series of new experimental studies.     

ERP study of pre-attentive auditory processing in treatment-refractory schizophrenia

Event-related potential (ERP) studies have demonstrated impaired auditory sensory processing in patients with schizophrenia, as reflected in abnormal mismatch negativity (MMN). We sought to extend this finding by evaluating MMN in 13 treatment-refractory patients with schizophrenia, and 14 age- and gender-matched healthy controls. Subjects responded to infrequent visual stimulation while ignoring binaurally presented auditory tones. The amplitude and topographical pattern of the MMN were analyzed. The control group presented the expected reduction in the amplitude of the MMN from frontal to central and parietal locations. In comparison, the MMN amplitude was not reduced in the treatment-refractory patients, and was largest at the central-posterior electrode location. In addition, patients displayed larger negativities at left frontal, and left- and right-temporal electrode locations than the control subjects. These findings are consistent with pre-attentive abnormalities in treatment-refractory patients with schizophrenia.     

Lost in thought: cognitive load and the processing of addressees' feedback in verbal communication

Two experiments tested if cognitive load interferes with perspective-taking in verbal communication even if feedback from the addressee is available. Participants gave instructions on the assembly of a machine model. In Experiment 1, cognitive load was demonstrated to be a function of the complexity of assembly steps. In Experiment 2, position of feedback (during simple vs. during complex steps) and type of feedback (question vs. ambiguous interjection) were manipulated. With simple steps, speakers' responses were a function of feedback type. Speakers responded differently to questions than to interjections. With complex steps, however, responses were a function of cognitive load. Regardless of the type of feedback, most speakers simply repeated their previous utterances.     

"Capacity" reconsidered: interindividual differences in language comprehension and individual alpha frequency

The influence of interindividual differences in cognitive mechanisms on language comprehension remains controversial not only due to conflicting experimental findings, but also in view of the difficulty associated with determining which measure should be used in participant classification. Here, we address the latter problem by proposing that an electrophysiological measure, individual alpha frequency (IAF), may be a suitable means of classifying interindividual differences in sentence processing. Interindividual differences in IAF have been shown to correlate with performance on memory tasks and speed of information processing. In two experiments using event-related brain potentials (ERPs), IAF-based participant groups differed systematically with regard to the processing of ambiguous sentences such that the low-IAF group showed a sustained positivity in the ambiguous region, while the high-IAF group did not. These interindividual differences were independent of whether the ambiguity was syntactic (Experiment 1) or sentence-level semantic (Experiment 2). Moreover, they were reliable only when participants were classified according to IAF, but not in classifications based on reading span, speed of processing (reaction time), or accuracy of processing (error rate).     

Secure and defensive high self-esteem

Long-standing theories have suggested high self-esteem (SE) can assume qualitatively different forms that are related to defensiveness. The authors explored whether some high-SE individuals are particularly defensive because they harbor negative self-feelings at less conscious levels, indicated by low implicit SE. In Study 1, participants high in explicit SE but low in implicit SE showed the highest levels of narcissism--an indicator of defensiveness. In Studies 2 and 3, the correspondence between implicit and explicit SE predicted defensive behavior (in-group bias in Study 2 and dissonance reduction in Study 3), such that for high explicit-SE participants, those with relatively low implicit SE behaved more defensively. These results are consistent with the idea that high SE can be relatively secure or defensive.