Transcutaneous vagus nerve stimulation (tVNS) enhances conflict-triggered adjustment of cognitive control

Response conflicts play a prominent role in the flexible adaptation of behavior as they represent context-signals that indicate the necessity for the recruitment of cognitive control. Previous studies have highlighted the functional roles of the affectively aversive and arousing quality of the conflict signal in triggering the adaptation process. To further test this potential link with arousal, participants performed a response conflict task in two separate sessions with either transcutaneous vagus nerve stimulation (tVNS), which is assumed to activate the locus coeruleus-noradrenaline (LC-NE) system, or with neutral sham stimulation. In both sessions the N2 and P3 event-related potentials (ERP) were assessed. In line with previous findings, conflict interference, the N2 and P3 amplitude were reduced after conflict. Most importantly, this adaptation to conflict was enhanced under tVNS compared to sham stimulation for conflict interference and the N2 amplitude. No effect of tVNS on the P3 component was found. These findings suggest that tVNS increases behavioral and electrophysiological markers of adaptation to conflict. Results are discussed in the context of the potentially underlying LC-NE and other neuromodulatory (e.g., GABA) systems. The present findings add important pieces to the understanding of the neurophysiological mechanisms of conflict-triggered adjustment of cognitive control.     

Personality Trait Differences Between Young and Middle‐Aged Adults: Measurement Artifacts or Actual Trends?

A growing body of research demonstrates that older individuals tend to score differently on personality measures than younger adults. However, recent research using item response theory (IRT) has questioned these findings, suggesting that apparent age differences in personality traits merely reflect artifacts of the response process rather than true differences in the latent constructs. Conversely, other studies have found the opposite—age differences appear to be true differences rather than response artifacts. Given these contradictory findings, the goal of the present study was to examine the measurement equivalence of personality ratings drawn from large groups of young and middle‐aged adults (a) to examine whether age differences in personality traits could be completely explained by measurement nonequivalence and (b) to illustrate the comparability of IRT and confirmatory factor analysis approaches to testing equivalence in this context. Self‐ratings of personality traits were analyzed in two groups of Internet respondents aged 20 and 50 (n = 15,726 in each age group). Measurement nonequivalence across these groups was negligible. The effect sizes of the mean differences due to nonequivalence ranged from –.16 to .15. Results indicate that personality trait differences across age groups reflect actual differences rather than merely response artifacts.     

Models and scientific representations or: who is afraid of inconsistency?

I argue that if we make explicit the role of the user of scientific representations not only in the application but also in the construction of a model or representation, then inconsistent modeling assumptions do not pose an insurmountable obstacle to our representational practices.     

Obsessive-compulsive personality disorder and behavioral disinhibition

Although obsessive-compulsive personality disorder (OCPD) is an Axis II diagnosis that is not commonly associated with behavioral disinhibition, the literature contains reports of occasional explosive aggressive outbursts. Existing explanations of OCPD etiology do not address the coexistence of compulsive and impulsive features witnessed in some subpopulations of patients. In this study, the authors present a compensatory theory of OCPD in an effort to explain clinical observations of an unexpectedly large number of OCPD diagnoses among patients clinic referred and self-referred for aggression problems.     

Sun compass orientation in seed-caching corvids: its role in spatial memory

The role of sun compass orientation in spatial memory of Clark’s nutcrackers, Nucifraga columbiana, and pinyon jays, Gymnorhinus cyanocephalus, was studied in a series of cache recovery experiments. Birds were tested in an octagonal outdoor aviary with sand-filled cups inserted in the floor. For caching, only 12 such cups in a 90° sector were available, while for recovery 4–7 days later all 48 cups in the entire aviary were open. In control tests, the birds concentrated their search activity in the sector where they had cached. When their internal clock was shifted 6 h between caching and recovery, pinyon jays shifted their search activity to the 90° adjacent sector, as predicted if the sun compass was used. Clark’s nutcrackers did not respond to the first clock-shift; however, they, too, shifted their search activity after a second clock-shift back to normal. This suggests that the sun compass is a component of spatial memory in both species. Clark’s nutcrackers, however, seem to rely on their sun compass to a lesser degree than pinyon jays or the previously studied scrub jays. A comparison of the findings indicates that the role of the sun in spatial memory might reflect differences in habitat and ecology of the three corvid species. Received: 18 February 1999 / Accepted after revision: 17 September 1999     

Responding to negative social identity: a taxonomy of identity management strategies

Taken from literature on social identity theory and social comparison theory, 12 strategies of identity management were identified as possible responses to negative social identity. A taxonomy with two orthogonal axes is proposed as theoretical organization of these diverse strategies. While the first axis considers responses as being either individual or collective, the second axis refers to the distinction between behaviours and cognitions. It is assumed that the German unification process implied a lower status position of East Germans relative to West Germans on relevant comparison dimensions, and that East Germans have to deal with this threat to their identity. Hence, data of an East German sample are used to empirically systematize identity management strategies, and, thus, to test the proposed taxonomy. Results support the expected four-factor solution only for those strategies taken from social identity theory, while the responses derived from social comparison research build a fifth factor. In addition, the empirical assignments of strategies to cells of the taxonomy are only partly in line with the expected pattern. The empirical findings suggest some clarification and modifications of the proposed response taxonomy. The most important refers to a re-interpretation of the taxonomy's first axis, which now differentiates between responses according to the specific changes of the comparison parameters they imply. © 1998 John Wiley & Sons, Ltd.     

Reliability estimates for the immediate and delayed memory tasks

The Immediate and Delayed Memory Tasks are variations of the Continuous Performance Test. While previous research with the tasks has focused on group performance across multiple blocks and sessions, reliability estimates have not been established. We estimated reliability (1) between blocks of a single testing session (N=106), (2) across four sessions within a single testing day (N=20), and (3) across sessions on four consecutive testing days (N=20). Analyses indicated that the primary variable of interest, i.e., commission of errors, showed acceptable reliability within and across testing periods.     

Temporal stability of the Wisconsin Card Sorting Test in a chronic traumatic brain injury sample

The aim of the present study was to investigate the temporal stability of the Wisconsin Card Sorting Test (WCST) in a clinical population with documented brain pathology, stable cognitive deficits, and for whom repeated testing is common: chronic severe traumatic brain injury (TBI). Participants were 34 patients at least 1 year post severe TBI living at a large residential rehabilitation facility. The WCST was administered in standard fashion with both the standard and 64-card versions scored. All derived scores with norms were examined. Results indicated acceptable temporal stability of most scores for both the standard and short WCST, although the stability of the WCST-64 was poorer than for the standard WCST. Three sets of significant change indices are provided for clinical use.