The worried mind: autonomic and prefrontal activation during worrying

To study the psychophysiological correlates of worrying, the authors recorded heart rate, respiratory sinus arrhythmia (RSA), skin conductance level, and alpha electroencephalographic asymmetry in healthy males during baseline, relaxation, worry induction, and anticipation of an impromptu speech task. Compared with baseline, relaxation, and anticipation, worrying was associated with greater heart rate and lower RSA. Worrying was further characterized by higher skin conductance levels compared with baseline but lower levels than during anticipation. Finally, worrying was associated with relatively greater left frontal activity compared with anticipation. Trait public speaking anxiety was positively correlated with left frontal activity during worrying. These results support the notion that worrying is a unique emotional state that is different from fearful anticipation.     

Prosocial emotions and helping: the moderating role of group membership

In this article, the authors introduce and test a group-level perspective on the role of empathy and interpersonal attraction in helping. In line with our predictions, Study 1, a longitudinal field study of 166 AIDS volunteers, confirmed that empathy was a stronger predictor of helping when the recipient of assistance was an in-group member than when that person was an out-group member. Also as hypothesized, attraction was a stronger predictor of helping when the recipient was an out-group member than when that person was an in-group member. Study 2 replicated and further extended these results in a laboratory experiment on spontaneous helping of a person with hepatitis. Strengthening the validity of the findings, in both studies the effects of empathy and attraction held up even when the authors statistically controlled for potential alternative predictors of helping. The theoretical and practical implications of these findings for helping in intergroup contexts are discussed.     

Events in Branching Time

The concept of event is one of the key notions of many theories dealing with causality or agency. In this paper we study different approaches to events that share the basic assumption that events can be analyzed fruitfully in branching-time structures. The terminological framework developed thereby may be helpful for further analyses in the fields of causality and agency and also in those fields of computational semantics, where similar concepts are considered.     

Haptic detection of sine-wave gratings

We studied human haptic perception of sine-wave gratings. In the first experiment we measured the dependence of amplitude detection thresholds on the number of cycles and on the wavelength of the gratings. In haptic perception of sine-wave gratings, the results are in agreement with neural summation. The rate at which detection thresholds decrease with increasing number of cycles is much higher than can be accounted for by probability summation alone. Further, neural summation mechanisms describe the detection thresholds accurately over the whole spatial range probed in the experiment, that is wavelengths from 14 mm up to 225 mm. Earlier, we found a power-law dependence of thresholds on the spatial width of Gaussian profiles (Louw et al, 2000 Experimental Brain Research 132 369-374). The current results extend these findings; the power-law dependence holds not only for Gaussian profiles, but also for a broad range of sine-wave gratings with the number of cycles varying between 1 and 8. Haptic perception involves tactual scanning combined with an active, dynamic exploration of the environment. We measured characteristics of the velocity and force with which stimuli were scanned while performing a psychophysical task. One particularly surprising finding was that, without being instructed, participants maintained an almost constant scanning velocity during each 45-min session. A constant velocity in successive trials of the experiment might facilitate or even be necessary for discrimination. Further, a large systematic dependence of velocity on scanning length was found. An eightfold increase in scanning length resulted in about a fourfold increase in scanning velocity. A second experiment was conducted to study the influence of scanning velocity on psychophysical detection thresholds. This was done by systematically imposing specific scanning velocities to the participants while the thresholds were measured. The main result of the second experiment was that psychophysical detection thresholds are constant over a relatively broad range of scanning velocities.     

Representation facilitates reasoning: what natural frequencies are and what they are not

A good representation can be crucial for finding the solution to a problem. Gigerenzer and Hoffrage (Psychol. Rev. 102 (1995) 684; Psychol. Rev. 106 (1999) 425) have shown that representations in terms of natural frequencies, rather than conditional probabilities, facilitate the computation of a cause's probability (or frequency) given an effect--a problem that is usually referred to as Bayesian reasoning. They also have shown that normalized frequencies--which are not natural frequencies--do not lead to computational facilitation, and consequently, do not enhance people's performance. Here, we correct two misconceptions propagated in recent work (Cognition 77 (2000) 197; Cognition 78 (2001) 247; Psychol. Rev. 106 (1999) 62; Organ. Behav. Hum. Decision Process. 82 (2000) 217): normalized frequencies have been mistaken for natural frequencies and, as a consequence, "nested sets" and the "subset principle" have been proposed as new explanations. These new terms, however, are nothing more than vague labels for the basic properties of natural frequencies.     

The P600 as an indicator of syntactic ambiguity

In a study using event-related brain potentials, we show that the current characterization of the P600 component as an indicator of revision processes (reanalysis and repair) in sentence comprehension must be extended to include the recognition of syntactic ambiguity. By comparing the processing of ambiguous and unambiguous sentence constituents in German, we show that the P600 is elicited when our language processing system has syntactic alternatives at a certain item given in the input string. That the P600 is sensitive to syntactic ambiguity adds crucial evidence to current debates in psycholinguistic modelling, as the results clearly favour parallel models of syntactic processing which assume that ambiguity is recognized and costly.     

Predictive validity of an Implicit Association Test for assessing anxiety

The Implicit Association Test (IAT) was adapted to measure anxiety by assessing associations of self (vs. other) with anxiety-related (vs. calmness-related) words. Study 1 showed that the IAT-Anxiety exhibited good internal consistency and adequate stability. Study 2 revealed that the IAT-Anxiety was unaffected by a faking instruction. Study 3 examined the predictive validity of implicit and explicit measures and showed that the IAT-Anxiety was related to changes in experimenter-rated anxiety and performance decrements after failure. Study 4 found that several behavioral indicators of anxiety during a stressful speech were predicted by the IAT. Taken together, these studies show that the IAT-Anxiety is a reliable measure that is able to predict criterion variables above questionnaire measures of anxiety and social desirability.     

Famous personal names and the right hemisphere: the link keeps missing

In this reply to the comment by VanLancker and Ohnesorge (2002), we present the case that current evidence supports the role of left hemisphere in the recognition of famous personal names. We argue that this conclusion is in line not only with the results of Schweinberger, Landgrebe, Mohr, and Kaufmann (2002), but also with the evidence from methods other than divided visual field studies (e.g., PET and ERP studies).We show that our view is also supported by a new set of experiments that address a major concern raised by VanLancker and Ohnesorge in their comment and discuss why the evidence they present does not provide conclusive support to their right hemisphere hypothesis. One of the several possible reasons for this failure is that famous name stimuli may be less suitable than personally familiar stimuli to elicit personally relevant, affective aspects of recognition.     

Social contacts and production of 50-kHz short ultrasonic calls in adult rats

The goal of the study was to provide evidence that the production of 50-kHz calls by adult rats is driven by potential or direct social contacts. The calls have been studied during daily visits to a cage by single or paired rats. Repeated exposure of rats to the cage frequently visited by other rats or direct contact between rats significantly increased the number of 50-kHz calls. The increase in production of 50-kHz calls was reduced by 78% after intrapreoptic-anterior hypothalamic injection of MK-801, an N-methyl-D-aspartate-type glutamate receptor antagonist. Calls emitted in all situations had a similar acoustic profile. It was found that 50-kHz calls were produced in anticipation of, and/or during, direct social contacts among adult rats and were predominantly initiated by olfactory stimuli. The calls seem to express an appetitive behavioral state in which the central glutamatergic mechanism is implicated.