6.5 Shifting: switching attentional focus within working memory

Objectives:

A. Understand that Shifting is an executive function confined to working memory.

B. Appreciate Shifting for its mysterious nature and unique features, including that the collaborative presence of the other two core EF components is prerequisite.

C. Identify common classroom behaviours that reflect Shifting and school readiness.

The third component of the three-component model of executive function is Shifting, our ability to switch our focus of attention within working memory from one task to another or between subtasks, steps, or rules of a task. In the research literature, it is also referred to as “switching” or “cognitive flexibility.”

The act of Shifting is sometimes confused with eye movements and visual attention. However, researchers distinguish Shifting, an entirely voluntary EF that occurs in the frontal lobes, and changes in visual attention that can inform working memory but are coordinated by sensorimotor regions in the parietal and occipital lobes as well as lower midbrain areas. In the following paragraphs, three clarifying examples are presented to illustrate how Shifting, as an executive function, involves working memory processes and does not directly involve shifts in visual attention between objects or events in our surroundings.

Example 1: If a teacher asks 10-year-old students to mentally calculate 40 divided by 16, a proficient student will likely begin by estimating how many 16s will make 40 or almost 40. Let’s suppose a student incorrectly estimates 3 but soon realizes that 3 multiplied by 16 will yield a number larger than 40. What must happen next? The student must dismiss (strongly inhibit) the 3 and try working with 2 instead. That is an example of Shifting because the student has shifted attentional focus within working memory from one operand to another.

Example 2: Proceeding, the student multiplies 2 by 16 for a total of 32 and then subtracts that 32 from the 40. Moving from the multiplying step to the subtraction step is a second example of Shifting. Attentional focus in working memory switched from one operation to another.

Example 3: Minutes later, the teacher might ask students to store away all math materials and prepare for a reading activity. Switching tasks in this way is a third example of the Shifting component of EF. The involvement of external objects and events in this example is irrelevant. The key here is that the student is required to make a shift in working memory between two “mental sets,” that is, from a math class frame of mind to a reading class frame of mind.

Clearly, Shifting is a familiar and yet mysterious EF capability. We can examine our own conscious experience and recognize the frequent need to shift our mental focus of attention, that is, switch our thoughts and/or behaviours. It is also true that many research teams since Miyake et al. (2000) have replicated the use of varied EF tasks to statistically confirm a third distinguishable Shifting component. On the other hand, we may justifiably say that of the three core components of EF, Shifting has the weakest standalone identity. It never truly functions independently and can only be characterized in terms of its interactions, like a ghost that leaves footprints. Readers are encouraged to review the Table 6.3 listing of Shifting look-fors in school-ready youngsters and consider how each might also implicate some measure of Updating or Inhibition.

The challenge researchers face in isolating Shifting for study arises from the “shared but distinct” nature of EFs mentioned above. That is another way of saying we believe a substantial common factor drives each of the three core EF components. To ensure that readers gain a suitable grasp of Shifting, let us articulate a few of its key distinguishing features. One of those is its delayed onset and prolonged development during childhood. Updating and Inhibition are established and working closely for some time before Shifting begins to emerge and contribute meaningfully between 3 and 5 years of age. Garon et al. (2014) maintain that Shifting is a “more complex” component because it can only operate with the other two underway (p. 715). Another highly regarded study examined EF development in four- to 13-year-olds and found that even 13-year-olds are not yet capable of adult-level Shifting (Davidson, 2006).

A second distinguishing feature of Shifting is its nimble versatility. For Shifting to occur, a task-relevant focus of attention must be at least temporarily deselected so that something else can become the new focus of attention. However, one cannot simply abandon an outgoing focus for the simple reason it was highly salient only a moment earlier. A discarded focus must be inhibited, and perhaps strongly, if the new focus is to actively engage with a minimum of interference. As straightforward as that transition may sound, the Shifting process is surely an exquisite and masterfully coordinated working memory activity. On the other hand, some readers may decide to view the “nimble versatility” of the Shifting component as

simply reflecting how deftly all three maturing components learn to interact.

A third distinguishing feature of Shifting is that it always incurs a cost. A Shifting cost can take the form of a longer response time, higher error rate, or drop in working memory capacity for the current task. The type and size of the cost can vary for reasons that can include one’s age or task experience but can also tie to how the shift is initiated. Even though all EF shifts are voluntary and purposeful, they may be initiated in quite different ways. Some shifts are initiated by external cues, such as when a task-relevant perceptual event calls for revising an existing plan or replacing a mental set. Other shifts are initiated internally, as when a 10-year-old student chooses to forego multiplying by three and multiply by two instead. Readers may be surprised to learn that, as a rule, externally initiated shifts will incur lower costs than those initiated internally (see footnote 1). To their credit, teachers have been applying this counterintuitive knowledge long before Spector and Biederman (1976) provided the earliest empirical support. External structures such as outlining the morning schedule on the blackboard and procedural routines such as “math will always follow lunch recess” are often applied to cue students to activity transitions. These orienting supports ease Shifting costs and improve the flow of classroom experience, particularly for younger students.

Notes:

1. When Shifting is prompted by external cues, costs tend to be lower and may only amount to a few tenths of a second in response time. However, even the briefest delay can impact an outcome in a faster-moving situation, such as when a driver’s mental set must shift from cell phone back to road.