Trait and State Differences in Working Memory Capacity

Abstract

Everyday, we use the limited resources of working memory (WM) across situations. For example, we use them as we drive to work attempting to create and maintain a list of tasks and meetings for the day. In this situation, imagine that an unexpected phone call informs us that two meetings have been rescheduled : a first one for a different time today and a second one for tomorrow. After receiving this message, we attempt to update our newly created task list within WM to incorporate the new meeting times. At the same time, we resist interference from the new information we have received from the recent phone call and from other thoughts that this call has brought to mind. Bear in mind thatall this happens while we are driving a car, a task that is entirely different from creating, maintaining, andupdating our schedule for the day. Some of us manage these tasks simultaneously without much effort, whereas some of us cannot perform this sequence successfully, forgetting half of today's tasks or making the wrong turn. To complicate this picture, individual differences in managing information inWM partly stem from temporary states of mind that influence a successful management of the task at hand. Let us imagine that the driver had to prepare a talk for one of today's meetings and spent the whole night preparing. In addition, she might have had an argument with her spouse in the moming. Thus, she might have experienced sleep deprivation, stress, anxiety, and fatigue, which are additional factors that often worsen our ability to utilize WM. As the example above shows, the ability to effectively use and share the resource s of WM is influ­ enced by both stable and variable characteristics. In the complex WM system, different representations are temporarily stored in various formats, where attention control processes also interact to maintain and update temporarily active information. In our example, the driver' s daily schedule is the main­ tained information , and the rescheduling is updating the existing information to the new situation. Additionally, this example includes other information, such as thoughts unrelated to either driving or the daily schedule, extraneous information treated as irrelevant to the task. Such information usually accompanies the current goal and most of the time has to be suppressed or inhibited. Our chapter reviews research that examines individual differences in working memory capacity (WMC) across variety of tasks. We argue that these individual differences may reflect both a person's abiding traits as well as factors related to momentary fluctuations in a person's behavior and thoughts. We also look at possible implications in normal individuals as well as those suffering from psychopathology. In our exampl e, we have nam ed only a sub set of processes crucial for proper functioning of a complex WM sys tem. WM compri ses not only the processes needed for exe rting prop er memory strategies in order to co mplete a specific go al, such as encoding, maintenance, and retri eval, but also controlled attenti on. Cont rolled attention allows focusing on the relevant inform ation. WM diff ers from short­ term mem ory by the presen ce of this attention co mpo nent. Atte ntio nal co ntrol influences perfor­ mance on compl ex executive tasks differentl y at subsequent stages of processing, from encoding, maintenance, upd ating, and making decision s to responding. Maintenance and updating are cruc ial co mponents of WM. The ma inten anc e o f a current goal involves keeping informati on active for temporary processing and usin g that information for com­ plet ing the task. Upda ting, on the othe r hand , allows focusing attenti on on new information, so that we can change our stra tegies or ways to approach the goa l state. Furthermo re, updating allows new inform ation to become the focu s of attentio n. Thus, inform ation foc used previously is either over­ writt en or allow ed to deca y. Th erefore, the ability to successfully maint ain and upd ate information is pivotal in util izing WM reso urces, es pec ially in the face of distractors and other irrelevant material usually acc ompanying the relevant information. Later in processing, using the maint ained informa­ tion to guide selec tion o f the appro pria te respon se becomes es pec ially imp ort ant when an alternative op tion is prepotent but contextually inappr opriate. In our example, the driver may need to stop to get co ffee after having such a rough nigh t. However, she must tum righ t at an intersection where she normall y turns left to get to work . If she is temporaril y distracted , she may fall into the habit of getting I !.