Phase 1: Prepare
Step 1 Warm-up recall
From Module 1: what are the three stages of memory?
Private: nothing you type here is sent or stored.
Step 2 Learning goal
By the end of this lesson you can:
- define selective, divided and sustained attention (Foundation);
- explain the cost of task switching (Core);
- calculate time lost to interruptions (Core).
Phase 2: Teach
Step 3 A familiar example
You can follow one voice at a crowded party by focusing on it, but you cannot follow two conversations at once. Attention selects.
Step 4 Clear explanation
Attention is the process that selects what you will process. It acts like a filter, because far more reaches your senses than you can use.
| Term | Meaning | Study example |
|---|---|---|
| Selective attention | Focusing on one source and filtering out others | Reading while ignoring a noisy room |
| Divided attention | Trying to attend to two demanding tasks at once | Reading and replying to messages |
| Task switching | Moving attention from one task to another and back | Checking a phone every few minutes |
| Sustained attention | Keeping focus on one task over time | A 25 minute reading block |
Research on task switching (for example Rubinstein, Meyer and Evans, 2001) found that people are slower and make more errors when they switch between tasks than when they stay on one. Doing two demanding things “at once” is really switching quickly between them, with a cost each time. The cost is partly the time away and partly the time to recall where you were. Because the size of the cost depends on the tasks, the figures below are invented to show how to count it.
| Session (invented) | Planned | Interruptions | Time to refocus each | Time lost | Effective time |
|---|---|---|---|---|---|
| A | 60 min | 4 | 2 min | 8 min | 52 min |
| B | 90 min | 6 | 3 min | 18 min | 72 min |
In invented session B, six interruptions at 3 minutes each lose 18 minutes, which is one fifth of the 90 minutes planned. Counting your own interruptions for a week is a simple way to see the cost. See the entry on working memory for why interruptions are so damaging to complex tasks.
Step 5 Worked example (4 marks)
A 60-minute session (invented) has 5 interruptions, each costing 2 minutes to refocus. Find the effective time and the share lost.
- Time lost: 5 × 2 = 10 minutes. (1 mark)
- Effective time: 60 − 10 = 50 minutes. (1 mark)
- Share lost: 10 ÷ 60 = 1 ÷ 6, about 17 percent. (1 mark)
- Answer: 50 minutes effective; about 17 percent lost. (1 mark)
Phase 3: Practise
Step 6 Learner practice (instant-marked)
1. Selective attention is:
It is the filter.
2. Doing two demanding tasks “at once” is mostly:
Switching costs time and accuracy.
3. 4 interruptions at 2 minutes each lose:
4 × 2.
4. A 60-minute session losing 8 minutes has an effective time of:
60 − 8.
Phase 4: Close
Step 7 Recap
- Attention selects; it is limited.
- Task switching costs time and accuracy.
- Count interruptions to see their cost.
Step 8 Exit ticket (ungraded)
A 90-minute session has 3 interruptions of 4 minutes each. Find the effective time.
Private: nothing you type here is sent or stored.
Step 9 Go further (Extension)
Log your interruptions during one study session and compute the time lost.
Common mistakes
| Mistake | Why it fails |
|---|---|
| Believing you can read well while messaging | You are switching, not combining. |
| Counting only the interruption, not the refocus time | Include both. |
| Treating invented figures as measured | Measure your own. |
Limits. Switching costs vary with the tasks, and the figures in the examples are invented to show the arithmetic; measure your own.