Another way of looking at processing resource issues is through the lens of attention. In particular, divided attention addresses the question of how much information can be processed at any given time. Craik (1977) wrote that one of the clearest findings in cognitive aging research is the fact that older adults are more penalized when they must divide their attention between sources of information and/or responding. This type of task looks at how well people perform multiple tasks simultaneously. For example, paying attention to a lecture in class while simultaneously taking notes requires us to monitor two things (lecture content and what we are writing) simultaneously.
Life is full of situations in which we need to do at least two things at once. Two common examples are listening to a lecture while writing in a notebook and driving a car while conversing with a passenger. Each of these situations requires monitoring what is going on in at least two different domains. How well we are able to perform these multiple simultaneous tasks depends on how much attentional capacity we have available for each. To the extent that any one task requires a great deal of our capacity, our ability to do other things may be impaired.
Older adults report that dividing attention among most combinations of activities becomes more difficult with increasing age and, compared to young adults, rate most combinations of activities as more difficult (Tun & Wingfield, 1995). However, ratings of one’s ability to perform various types of activities vary a great deal across tasks. Keeping track of novel information in combinations of tasks is perceived as more difficult than activities involving routine tasks or speech processing. These findings reflect the importance of self-evaluations on how well people think they can (or did) perform, which may have important implications for performance.
Self-reports about the difficulty of divided – attention activities are consistent with other findings that older adults perform tasks requiring divided attention more poorly than younger adults do (McDowd & Shaw, 2000; Verhaeghen, Steitz, Sliwinski, & Cerella, 2003). Experimental research on divided attention is a good example of how conclusions about age differences can change in the face of new evidence. At one time, researchers were convinced that age-related decrements in divided attention were inevitable (Craik, 1977). But Somberg and Salthouse’s research in 1982 changed all that. By equalizing the amount of attention allocated on two tasks, Somberg and Salthouse were able to eliminate age differences on the divided – attention task. Other researchers have corroborated
Dividing one’s attention between driving and talking on the phone may be done better by young adults but may also not be safe for them to do.
Attention and Memory 191
How Good Are Your Notes?
At the beginning of this section we encountered several examples of divided-attention tasks. You are very familiar with one of them—writing notes while listening to a lecture.
An interesting developmental question is whether the ability to take good notes differs
with age. One way to find out informally is to compare the notes taken in the same class by younger adult and older adult students. If there are no older adults in your class, there may be some in other courses. Ask them if you can compare their notes with those of
someone much younger.
What predictions would you make based on the research evidence you have read thus far? What role would practice play in these differences? Whose notes are actually better? Why do you think this is?
Somberg and Salthouse’s findings (e. g., Wickens, Braune, & Stokes, 1987). Researchers have had to go back to the laboratory to try and account for these new data.
Subsequent studies have clarified things. It turns out that age differences are found on some divided – attention tasks and not others (Fernandes & Moscovitch, 2003; Whiting, 2003). Part of the explanation involves task complexity and practice. When the divided-attention tasks are relatively easy, age differences are typically absent. However, when the tasks become more complicated, then we observe age differences (Kramer & Larish, 1996; Salthouse, Fristoe, Lineweaver, & Coon, 1995). In other words, adults of all ages can perform multiple easy tasks simultaneously, but older adults do not do as well as younger adults when they must perform multiple difficult tasks at the same time.
Age differences on divided-attention tasks can be minimized if older adults are given extensive practice in performing the tasks, thereby reducing the demands on attention (Kramer, Larish, & Strayer, 1995; Tsang & Shaner, 1998). For example, when very large numbers of practice trials (from roughly 500 to over 11,000) are provided, age differences may disappear; with fewer practice trials (less than 300), age differences are often still found (Kramer et al., 1995; Kramer, Larish, Weber, &
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Bardell, 1999; Rogers, Bertus, & Gilbert, 1994). These results imply that older adults may be able to learn through experience how to divide their attention effectively between tasks. Check out this idea by completing the Discovering Development feature.
So, you may ask, when do older adults have difficulty performing multiple tasks simultaneously? You may have observed older adults having difficulty trying to remember something as they are walking down a staircase, or trying to simply walk and talk at the same time. Li and colleagues (Li et al.,
2001) found that older adults prioritize walking and maintaining balance at the expense of memory. In other words, older adults focused on the task that was most important to them, walking and balancing to prevent falls. Younger adults, on the other hand, optimized their memory performance and ignored walking and balancing. Similarly, Kemper et al. (2003) found that both younger and older adults were able to simultaneously walk and talk, but that they accomplished this by using different strategies. Younger adults reduced their sentence length and grammar complexity, while older adults reduced their rate of speech.
In sum, divided-attention ability per se does not differ with age. Rather, older adults are at a disadvantage when they must perform two or more
complex tasks simultaneously (McDowd & Shaw, 2000; Verhaeghen et al., 2003). Moreover, age differences on divided-attention tasks may actually reflect the fact that each task involves different component processes that are separately affected by aging (Fernandes & Moscovitz, 2003; Salthouse et al., 1995). This is exemplified in how older adults compensate by using strategies to focus on the task of most importance to them.
Integration: Attention and Cognitive Change in Older Adulthood
Finally, related constructs that must be considered when studying attentional capacity as a pool of resources available to support information-processing activity are automatic and effortful processing. In other words, a key assumption to information processing is that some processing occurs automatically whereas other processing requires effort. Researchers who study aging and cognition investigate both automatic processing and effortful processing, and then often look at differences in performance across the two categories.
Automatic processing places minimal demands on attentional capacity. Some automatic processes appear to be “prewired” in the sense that they require no attentional capacity and do not benefit from practice; others are learned through experience and practice (Smith & Earles, 1996). In either case, information that is processed automatically gets into the system largely without us being aware of it. For example, those who have been driving a car for many years are usually unaware of how hard they are pressing the accelerator pedal to make the car go forward from a stop. We will see that performance that is automatic in nature does not produce significant age differences in processing information.
In contrast, effortful processing requires all of the available attentional capacity. Most of the tasks involving deliberate memory, such as learning the words on a list, require effortful processing. In these cases, we are typically aware of what we are doing. For example, when we are first learning how to drive a car with a clutch, we are very aware of the information we are processing (e. g., how much to let up on the clutch versus how hard to press the accelerator pedal). It is with effortful processing that age differences tend to emerge.
Finally, when considering attentional resources, it is extremely important to ask the question: Is it a fixed capacity that decreases with age? Researchers have observed decline in older adults’ performance on laboratory tasks assessing memory, for example. However, a different picture may emerge when we consider that the functional capacity or resources necessary in specific task contexts can be modifiable depending upon the relevance and accessibility of knowledge and expertise related to the cognitive processes required (Hertzog, 2008). For example, two-process models have emerged that are similar to the automatic-effortful distinction discussed above. Under conditions where the task requirement is to simply have a familiarity with the information, there are no age differences. However, when there is effortful and deliberate processing involved to recollect the information, age differences emerge. Again, theories of cognitive aging are moving away from one-process views of cognitive functioning using standardized tests. These may underestimate older adults’ competencies. Instead, the question now asked is: When and under what circumstances will we observe age-related change in cognitive functioning, and when is that change problematic? (Hertzog, 2008).
1. Under what conditions do age differences disappear in inhibition tasks?
2. What are processing resources?
3. What are automatic processes?
4. Are attentional resources a fixed capacity that declines with age?