![]() ![]() Specifically, I argue that it is not reasonable when different studies reach similar conclusions (e.g., that effects of certain stimuli on or certain group differences in working memory performance were found), although these conclusions are based on different dependent variables (e.g., on reaction times in one study and on accuracy in another study). What these examples illustrate is that reaction times and accuracy in n-back tasks should not be interpreted interchangeably. It might be argued that it is at least debatable if emotional stimuli indeed affected working memory performance as participants' ability to discriminate between targets and non-targets was not influenced. Yet, the authors concluded that “allocating attention to affective information improved working memory” (p. In contrast, effects of emotional stimuli (here: faces) were only found for reaction times and not for accuracy in a recent study by Cromheeke and Mueller (2016). In light of these findings, how is interpretation of results affected when associations for some n-back task performance indices can be found but not for others? For example, in two studies that either used emotional words ( Kopf et al., 2013) or pictures of emotional scenes ( Marx et al., 2011) it was found that accuracy (but not reaction times) differed as a function of emotional valence of the stimuli. In the working memory task, however, there was more variability in accuracy and less variability in reaction times and, thus, they focused on interpreting accuracy results because “participants' efforts are generally focused more on performing the task accurately than responding as fast as they can” (p. The authors argued that there was a ceiling effect in accuracy and more meaningful variation in reaction times in the perception task and, thus, they focused on interpreting reaction time results. ![]() In that study, pictures of emotional scenes were used in a 0-back task (labeled as perception task) and a 2-back task (labeled as working memory task). (in press) further highlights the role of reaction times vs. In addition to these findings, a recent study by Hur et al. In visuospatial n-back tasks, reaction times (but not accuracy) were associated with reading span and digit span forward performance. For instance, higher accuracy (but not reaction times) in visuospatial, auditory, and dual 3-back tasks was correlated with higher fluid intelligence as measured with the Raven test. (2010) examined various n-back tasks and found several dissociations between reaction times and accuracy. Although this relationship exists, it appears that reaction times and accuracy have dissociable correlates. In other words, higher reaction times are associated with a higher number of errors. Similarly, reaction times and accuracy are usually negatively correlated (e.g., Carter et al., 1998). With increasing task difficulty (i.e., with increasing ns), reaction times usually increase and accuracy decreases (e.g., Jonides et al., 1997 Carlson et al., 1998 Perlstein et al., 2003 Harvey et al., 2005 Miller et al., 2009 Schmidt et al., 2009). Stimuli in classical n-back tasks are numbers or words, but pictorial versions, which display, for example, emotional scenes ( Marx et al., 2011 Hur et al., in press), faces ( Cromheeke and Mueller, 2016), or food ( Meule et al., 2012 Meule, 2016) have also been used in recent years.Īs dependent variables, most studies report response latencies (= reaction times) and accuracy (in %) or the number of errors. Yet, there are also studies, in which participants are required to indicate for each trial whether the stimulus represents a target or a non-target (e.g., by pressing two different buttons Jonides et al., 1997 Carlson et al., 1998 Perlstein et al., 2003 Harvey et al., 2005 Miller et al., 2009). In most studies, participants are required to respond with a button press to the relevant stimuli (= targets) and to withhold responses to distractor stimuli (= non-targets). Zero-back and 1-back versions are also often used as control conditions. Common versions are 2-back and 3-back tasks, in which participants have to respond to stimuli that have been presented two or three trials earlier. Here, participants are typically instructed to monitor a series of stimuli and to respond whenever a stimulus is presented that is the same as the one presented n trials previously. ![]() A widely used measure for the assessment of working memory function is the n-back task ( Owen et al., 2005). Working memory is an executive function, which involves holding information in mind and mentally working with it ( Diamond, 2013). ![]()
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