168 research outputs found

    When co-action eliminates the Simon effect: Disentangling the impact of co-actor' s presence and task sharing on joint-task performance.

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    Thisstudyaimedatassessingwhetherthemerebeliefofperformingataskwithanotherperson,whoisinchargeofthecomplementarypartofthetask,issufficientfortheso-calledjointSimoneffecttooccur.Inallthreeexperimentsofthestudy,participantssataloneinaroomandunderwenttwoconsecutiveGo/NoGotasksthatwereidenticalexceptfortheinstructions.InExperiment1,participantsperformedthetaskfirstindividually(baselinetask),andtheneitherco-actingwithanotherpersonwhorespondedfromanunknownlocationtotheNoGostimuli(jointtask)orimagingthemselvesrespondingtotheNoGostimuli(imaginativetask).Relativetothebaseline,theinstructionsoftheimaginativetaskmadetheSimoneffectoccur,whilethoseofthejointtaskwereineffectiveinelicitingtheeffect.Thisresultsuggeststhatsharingataskwithapersonwhoisknowntobeinchargeofthecomplementarytask,butisnotphysicallypresent,isnotsufficienttoinducetherepresentationofanalternativeresponseabletoproduceinterference,whichhappensinsteadwhentheinstructionsexplicitlyrequiretoimaginesucharesponse.Interestingly,weobservedthatwhentheSimoneffectwasalreadypresentinthebaselinetask(i.e.,whentheresponsealternativetotheGoresponsewasrepresentedintheindividualtaskduetonon-socialfactors),itdisappearedinthejointtask.Weproposethat,whennoinformationabouttheco-actor’spositionisavailable,thedivisionoflaborbetweentheparticipantandco-actorallowsparticipantstofilteroutthepossible(incidental)representationofthealternativeresponsefromtheirtaskrepresentation,thuseliminatingpotentialsourcesofinterference.ThisaccountissupportedbytheresultsofExperiments2and3andsuggeststhatundercertaincircumstancestask-sharingmayreducetheinterferenceproducedbytheirrelevantinformation,ratherthanincreaseit

    "Unfocus" on foc.us: Commercial tDCS headset impairs working memory

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    In this study, we tested whether the commercial transcranial direct current stimulation (tDCS) headset foc.us improves cognitive performance, as advertised in the media. A single-blind, sham-controlled, within-subject design was used to assess the effect of online and off-line foc.us tDCS—applied over the prefrontal cortex in healthy young volunteers (n = 24) on working memory (WM) updating and monitoring. WM updating and monitoring, as assessed by means of the N-back task, is a cognitive-control process that has been shown to benefit from interventions with CE-certified tDCS devices. For both online and off-line stimulation protocols, results showed that active stimulation with foc.us, compared to sham stimulation, significantly decreased accuracy performance in a well-established task tapping WM updating and monitoring. These results provide evidence for the important role of the scientific community in validating and testing far-reaching claims made by the brain training industry

    Genetic Characterization of Prairie Grass (\u3cem\u3eBromus Catharticus\u3c/em\u3e Vahl.) Natural Populations

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    Prairie grass, Bromus catharticus Vahl., is a winter annual or biennial grass, native of South America which is widely distributed in the Pampeana area of Argentina and also cultivated in temperate regions of the world. Morphophysiological traits are currently used to assess the variability from natural populations and cultivars of this species. Molecular markers, which are not influenced by the environment, allow a more accurate assessment of genetic variability. Previous results from our group (Puecher et al., 2001a) showed a narrow genetic basis for the prairie grass cultivars used in Argentina. On the other hand, we also observed that natural populations of this species collected in the typical area where prairie grass is cultivated in Argentina, showed a RAPD variability pattern similar to that previously observed for cultivars (Puecher et al., 2001b). The objective of this work was to establish, using RAPDs, the genetic relationships among prairie grass natural populations including accessions from the margins of the cultivation area of this species in Argentina
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