Task-order coordination in dual-task performance and the lateral prefrontal cortex: an event-related fMRI study

A crucial demand in dual tasks suffering from a capacity limited processing mechanism is task-order scheduling, i.e. the control of the order in which the two component tasks are processed by this limited processing mechanism. The present study aims to test whether the lateral prefrontal cortex (LPFC) is associated with this demand. For this, 15 participants performed a psychological refractory paradigm (PRP) type dual task in an event-related functional magnetic resonance (fMRI) experiment. In detail, two choice reaction tasks, a visual (response with right hand) and an auditory (response with left hand), were presented with a temporal offset of 200 ms, while the participants were required to respond to the tasks in the order of their presentation. Importantly, the presentation order of the tasks changed randomly. Based on previous evidence, we argue that trials in which the present task order changed as compared to the previous trial (different-order trials) impose higher demands on task coordination than same-order trials do. The analyses showed that cortical areas along the posterior part of the left inferior frontal sulcus as well as the right posterior middle frontal gyrus were more strongly activated in different-order than in same-order trials, thus supporting the conclusion that one function of the LPFC for dual-task performance is the temporal coordination of two tasks. Furthermore, it is discussed that the present findings favour the active scheduling over the passive queuing hypothesis of dual-task processing.     

Motivational and cognitive determinants of control during conflict processing

Previous studies suggest that both reward anticipation and expected or experienced conflicts activate cognitive control. The present study investigated how these factors interact during conflict processing. In two experiments, participants performed a variant of the Stroop task, receiving performance-dependent monetary rewards in some blocks. In addition, we manipulated the level of conflict-triggered reactive and expectancy-driven proactive control: In Experiment 1, we compared the Stroop effect after previously congruent and incongruent trials to examine the conflict adaptation effect (reactive control). We found that the level of motivation did not interact with conflict adaptation. In Experiment 2, we varied the proportion of congruent and incongruent trials to manipulate conflict expectancy (proactive control). The data suggest the effects of motivation to be less pronounced under conditions of high conflict expectancy. We conclude that the interaction of motivation with cognitive determinants of control depends on whether these activate proactive or reactive control processes.     

Effects of extensive dual-task practice on processing stages in simultaneous choice tasks

Schumacher et al. Psychological Science 12:101–108, (2001) demonstrated the elimination of most dual-task costs (“perfect time-sharing”) after extensive dual-task practice of a visual and an auditory task in combination. For the present research, we used a transfer methodology to examine this practice effect in more detail, asking what task-processing stages were sped up by this dual-task practice. Such research will be essential to specify mechanisms associated with the practice-related elimination of dual-task costs. In three experiments, we introduced postpractice transfer probes focusing on the perception, central response-selection, and final motor-response stages. The results indicated that the major change achieved by dual-task practice was a speed-up in the central response-selection stages of both tasks. Additionally, perceptual-stage shortening of the auditory task was found to contribute to the improvements in time-sharing. For a better understanding of such time-sharing, we discuss the contributions of the present findings in relation to models of practiced dual-task performance.     

A Defining Presidential Moment: 9/11 and the Rally Effect

Public approval ratings of George W. Bush surged after the 11 September 2001 terrorist attacks. This study used a quasi–experimental, within–respondents design to investigate the relative contribution of five factors to this classic rally effect: the stimulus event itself, Bush's speech that evening, media exposure, partisan support, and gender effects. Respondents were pretested on the morning of the attacks; one group was posttested immediately after the speech, another group 41 hours later. Stability of effects was examined through an additional study of Bush's 20 September 2001 speech to a joint session of Congress. The findings indicate that Bush's 11 September speech was the critical factor in this rally effect; none of the other factors contributed significantly.     

Walk the Talk: Financial Fairness in European Club Football

UEFA’s Financial Fair Play (FFP) regulations represent the most restrictive regulatory intervention European club football has ever seen. Put simply, it demands from clubs to operate on the basis of their own football-related incomes. While the policy has attracted considerable attention from the economic and social sciences, very few contributions systematically investigate it from a philosophical-ethical perspective. The present paper fills this research gap by posing questions on FFP in relation to fair play as a normative concept. We draw on sport economic assessments concerning potential outcomes of FFP and argue that the policy should go beyond the mere pragmatic goal of promoting financial sustainability and truly aim for creating a level playing field, otherwise it should not be labeled ‘fair play’.     

Valence processing bypassing the response selection bottleneck? Evidence from the psychological refractory period paradigm

The activation of semantic categories has often been claimed to occur in an attention-free, unconditionally automatic fashion (e.g., Bargh & Chartrand, 1999; Ferguson & Bargh, 2004). Using a dual-task procedure we tested whether the activation of valence categories is restricted by dual-task specific attentional limitations. For this reason we implemented a modified Eriksen-flanker task as Task 2 in a psychological refractory period paradigm. Participants were to judge the frequency of a tone in Task 1 and the valence of a target word in the presence of irrelevant flanker words in Task 2. Two different flanker categories ensured the activation of semantic categories instead of S-R based response activation. The most important result was an underadditive interaction between flanker congruency and the amount of temporal overlap between tasks that was independent of flanker type. Following the locus-of-slack logic, we interpret these findings as evidence for Task 2 processing parallel to bottleneck-stage processing in Task 1. This extends previous findings by showing that not only number categories (Fischer, Schubert, & Miller, 2007; Oriet, Tombu, & Jolicouer, 2005), but also semantic valence categories can be activated despite dual-task capacity limitations.     

Fibromyalgie und Leistungseinschränkung

Interdisciplinary guidelines allowed for new quality standards in pain appraisal. Simultaneously, the scientific notion of fibromyalgia changed from a subjectively overvalued malaise to a central disturbance of coping with stress, which is neurobiologically determined. Therefore, in this article a psychosomatics-based guide is given for the socio-medical appraisal of fibromyalgia with reference to the new International Classification for Functioning and Disability (ICF) of the World Health Organization (WHO). As illustration a case study is presented.     

Accessory stimuli modulate effects of nonconscious priming

In a recent study, it was shown that subliminal priming (SP) effects are affected by the temporal predictability of a stimulus onset. If predictability is not given, SP effects are eliminated (Naccache, Blandin, & Dehaene, 2002). In two experiments, we investigated how different levels of preparation for target processing affect SP effects. For this purpose, an accessory tone stimulus was presented at different times prior to a subliminal priming task. The results demonstrate a clear modulation of the SP effects at different foreperiod intervals. Relative to conditions without an accessory stimulus, SP effects were smaller for short foreperiod intervals of the accessory stimulus, and larger for long foreperiod intervals. The results suggest that the presentation of an accessory stimulus facilitates response activation processes because of the participants' enhanced level of preparation for stimulus processing.     

Training-specific adaptations of H- and stretch reflexes in human soleus muscle

The authors investigated the effect of physical exercise on reflex excitability in a controlled intervention study. Healthy participants (N = 21) performed 4 weeks of either power training (ballistic strength training) or balance training (sensorimotor training [SMT]). Both training regimens enhanced balance control and rate of force development, whereas reductions in peak-to-peak amplitudes of stretch reflexes and in the ratio of the maximum Hoffman reflex to the maximum efferent motor response (Hmax:Mmax) measured at rest were limited to SMT. The differences in reflex excitability between the training regimens indicated different underlying neural mechanisms of adaptation. The reduced reflex excitability following SMT was most likely induced by supraspinal influence. The authors discuss an overall increase in presynaptic inhibition of Ia afferent fibers as a possible mechanism.