In this section we are interested in how information is kept in one’s mind for additional processing into long-term memory or is being held temporarily during retrieval. How this happens involves work­ing memory.

Originally, this type of immediate memory process was conceptualized as passive short-term storage or short-term memory. The idea is that ind­ividuals have a limited capacity for remembering information (about seven chunks of information, Miller, 1956). The question is whether older adults maintain this capacity. A typical short-term mem­ory task measures the longest span of digits an indi­vidual can recall immediately after presentation. Studies have typically reported small or no age dif­ferences on these simple and passive span measures (Zacks et al., 2000).

However, some researchers have found evidence that, depending on the stimuli presented, older adults perform more poorly on simple span tasks than younger adults (Zacks et al., 2000). This age difference in span, though, can be accounted for by other more active information-processing variables involved in short-term memory (Verhaeghen et al.,

1993) . One such variable is working memory, an age-sensitive factor that affects long-term mem­ory processing, for example, encoding informa­tion into long-term memory (Zacks et al., 2000). Working memory is the active processes and struc­tures involved in holding information in mind and simultaneously using that information, sometimes in conjunction with incoming information, to solve a problem, make a decision, or learn new information (Zacks et al., 2000). Researchers typically consider it an umbrella term for many similar short-term holding and computational processes relating to a wide range of cognitive skills and knowledge domains (Zacks et al., 2000). This places working memory right in the thick of things—it plays an
active, critical, and central role in encoding, storage, and retrieval.

Recall that sensory memory has a very large capacity to deal with incoming information. In contrast, researchers generally agree that working memory has a relatively small capacity. This capac­ity limitation of working memory operates like a juggler who can only keep a small number of items in the air simultaneously. Because working memory deals with information being processed right at this moment, it also acts as a kind of mental scratchpad. This means that unless we take direct action to keep the information active, the page we are using will get used up quickly and tossed away. For this rea­son, we need to have some way to keep information in working memory.

Most evidence indicates that there is greater age-related decline in working memory relative to passive short-term memory described earlier (Bopp & Verhaeghen, 2005; Zacks et al., 2000), although the extent of the decline is still in doubt. Researchers find that when the information load is
increased (e. g., the number of tasks to be performed increases), older adults’ lower storage capacity results in impaired working memory performance more so than for younger adults (Chen, Hale, & Myerson, 2003; McCabe & Hartman, 2003). This finding is consistent with the notion that the ability to allocate capacity in working memory to more than one task declines with age.

Salthouse and colleagues (1996; Verhaeghen & Salthouse, 1997) believe that working memory is the key to understanding age differences in memory. They argue that the loss of some of the ability to hold items in working memory may limit older adults’ overall cognitive functioning. For example, many researchers propose working memory as the basis for understanding reasoning (Brigman & Cherry, 2002; Salthouse et al., 2003) and memory (Park et al., 2002). This idea is based on the extremely important role that working memory is believed to play in information processing. For example, working memory is where all the action is during processing: It is where information obtains meaning

and is transformed for longer storage. As a result, age differences here would have profound implica­tions for just about all aspects of memory. The idea is that if information becomes degraded or is only partially integrated into one’s knowledge base, it will be very difficult to remember it.

However, some evidence suggests that age dif­ferences in working memory are not universal. For example, working memory appears to depend on the type of information being used and may even vary across different tasks (Hale, Myerson, Rhee, Weiss, & Abrams, 1996; Logie, 1995). Such differ­ences complicate matters. Chen, Hale, and Myerson (2003) find that age-related decline in spatial work­ing memory is much greater than that in verbal working memory, although there is decline in both types of working memory. In other words, age dif­ferences were more pronounced in tasks that asked the individual to remember locations than in those where they were asked to remember digits.

Recent research has examined what causes work­ing memory deficits in older adults. Oberauer and colleagues (2003) found that older adults have no trouble initially accessing multiple pieces of infor­mation at one time. The source of the problem is that they have difficulty juggling all of the elements once they are accessed. Interestingly, West and col­leagues (2002) found that time of day affected the strength of age differences observed in working memory. Typically alertness is higher in the morn­ing for older adults and in the evening for younger adults. When working memory was tested in the evening, the age differences were much stronger.

Overall, the evidence for age-related decline in working memory is not entirely clear; however, there is compelling evidence for how age differ­ences in working memory relate to performance on more complex cognitive tasks. Yet, a great deal more needs to be done. Differential magnitude of decline in different domains of working memory suggest that it may not be a matter of overall general decline, but much more specified in certain areas and not others. There is little doubt at this point of the importance of working memory as a critical concept for understanding age-related differences in memory performance. For example, researchers
have begun to show that working memory may be key to understanding the age differences in recall performance, especially in situations in which few cues for remembering exist (Park et al., 2002).