Can executive control be influenced by performance feedback? Two experimental studies with younger and older adults

Executive control describes a wide range of cognitive processes which are critical for the goal-directed regulation of stimulus processing and action regulation. Previous studies have shown that executive control performance declines with age but yet, it is still not clear whether different internal and external factors—as performance feedback and age—influence these cognitive processes and how they might interact with each other. Therefore, we investigated feedback effects in the flanker task in young as well as in older adults in two experiments. Performance feedback significantly improved executive performance in younger adults at the expense of errors. In older adults, feedback also led to higher error rates, but had no significant effect on executive performance which might be due to stronger interference. Results indicate that executive functions can be positively influenced by performance feedback in younger adults, but not necessarily in older adults

Stopping Speed in the Stop-Change Task: Experimental Design Matters!

Previous research comparing the speed of inhibiting a motor response in no-foreknowledge vs. foreknowledge conditions revealed inconsistent findings. While some studies found stopping to be faster in the no-foreknowledge condition, others reported that it was faster in the foreknowledge condition. One possible explanation for the heterogeneous results might be differences in experimental design between those studies. Given this, we wanted to scrutinize whether it makes any difference if foreknowledge and no-foreknowledge are investigated in a context in which both conditions are presented separated from each other (block design) vs. in a context in which both conditions occur intermingled (event-related design). To address this question a modified stop-change task was used. In Experiment 1 no-foreknowledge and foreknowledge trials were imbedded in a block design, while Experiment 2 made use of an event-related design. We found that inhibition speed as measured with the stop signal reaction time (SSRT) was faster in the foreknowledge as compared to the no-foreknowledge condition of the event-related study, whereas no differences in SSRT between both conditions were revealed in the block design study. Analyses of reaction times to the go stimulus reflect that participants tended to slow down their go responses in both experimental contexts. However, in the foreknowledge condition of the event-related study, this strategic slowing was especially pronounced, a finding we refer to as strategic delay effect (SDE), and significantly correlated with SSRT. In sum our results suggest that inhibition speed is susceptible to strategic bias resulting from differences in experimental setup

Searches for resonances in the tb and tc final states at the high-luminosity LHC

We study resonances decaying to one top quark and one additional quark (b or c) at the low- luminosity and high-luminosity 14 TeV LHC and at a future 33 TeV hadron collider in the context of Snowmass 2013. A heavy W boson that preferentially couples to quarks can be found through its decay to tb. A Kaluza-Klein gluon might have a significant branching ratio to tc. The final state in these searches has a lepton and neutrino from a W boson decay plus two jets, at least one of which is b-tagged. We give expected limits as a function of W boson and KKg masses for different collider energy and integrated luminosity options.We study resonances decaying to one top quark and one additional quark (b or c) at the low- luminosity and high-luminosity 14 TeV LHC and at a future 33 TeV hadron collider in the context of Snowmass 2013. A heavy W boson that preferentially couples to quarks can be found through its decay to tb. A Kaluza-Klein gluon might have a significant branching ratio to tc. The final state in these searches has a lepton and neutrino from a W boson decay plus two jets, at least one of which is b-tagged. We give expected limits as a function of W boson and KKg masses for different collider energy and integrated luminosity options

A reaction-time adjusted PSI method for estimating performance in the stop-signal task.

A central experimental task in executive control research is the Stop-signal task, which allows measuring the ability to inhibit dominant responses. A crucial aspect of this task consists of varying the delay between the Go- and Stop-signal. Since the time necessary to administer the task can be long, a method of optimal delay choice was recently proposed: the PSI method. In a behavioral experiment, we show a variant of this method, the PSI marginal method, to be unable to deal with the Go-response slowing often observed in the Stop-signal task. We propose the PSI adjusted method, which is able to deal with this response slowing by correcting the estimation process for the current reaction time. In several sets of behavioral simulations, as well as another behavioral experiment, we document and compare the statistical properties of the PSI marginal method, our PSI adjusted method, and the traditional staircase method, both when reaction times are constant and when they are linearly increasing. The results show the PSI adjusted method's performance to be comparable to the PSI marginal method in the case of constant Go-response times, and to outperform the PSI marginal method as well as the staircase methods when there is response slowing. The PSI adjusted method thus offers the possibility of efficient estimation of Stop-signal reaction times in the face of response slowing

How females think about themselves and how they assume that significant others think about them: The influence of perspective taking on self-referential processing

People maintain a positive self-concept through positive self-appraisals (Self-Serving Bias Effect, SSBE) and a diminished memory for self-threatening information (Mnemic-Neglect Effect, MNE). Other people also influence a person's self-concept. This study investigated SSBE and MNE in 60 females by using a trait-judgment paradigm applying two perspectives (self- and third-person appraisals) and a recall task. Additionally, self-esteem was assessed as an associated factor. SSBE and MNE were found in both kinds of appraisal perspectives. Interestingly, participants saw themselves as even more positive in reflected appraisals. SSBE and self-esteem were associated only in self-appraisals, indicating a larger SSBE on self-appraisals with raising self-esteem. In conclusion, both what females think about themselves and how they assume that others think about them preserve their overall positive self-concept

Strategies of selective changing: Preparatory neural processes seem to be responsible for differences in complex inhibition

Selective inhibition describes the stopping of an action while other actions are further executed. It can be differentiated between two strategies to stop selectively: the fast but global stop all, then discriminate strategy and the slower but more selective first discriminate, then stop strategy. It is assumed that the first discriminate, then stop strategy is especially used when information regarding which action might have to be stopped is already available beforehand. Moreover, it is supposed that both strategies differ in matters of basal ganglia pathways used for their execution. Aim of the present study was to investigate the use of the two strategies in situations requiring selective changing of an action. Eighteen healthy male participants performed a selective stop-change task with informative and uninformative cues during fMRI. Behavioral results show that informative cues led to a benefit in both inhibition times and selectivity. FMRI data revealed that the same cortico-subcortical pathway was used with informative and uninformative cues. Behavioral and neuronal results indicate that participants used the first discriminate, then stop strategy for selective inhibition irrespective of the amount of previously available information. Moreover, the neural activity data indicate that the benefit in the informed condition was produced by an efficient preparation for the concrete change process. Possible factors that might affect which strategy is used for selective stopping are the level of previously available information (foreknowledge) and the experimental set-up, as e.g. task complexity