Case Study

Based on this scenario, explain how the reversal phase (removing the tactile tool) helps the psychologist establish internal validity, and describe what the psychologist must assume about the tactile tool's effect to justify a causal conclusion.

Case context: A educational psychologist wants to study if a tactile focus tool reduces classroom off-task behavior in a student. The psychologist records baseline off-task behavior (A), introduces the tactile tool (B) and observes a decrease in off-task behavior, and then removes the tool (A). The off-task behavior subsequently returns to baseline levels.

Question: Based on this scenario, explain how the reversal phase (removing the tactile tool) helps the psychologist establish internal validity, and describe what the psychologist must assume about the tactile tool's effect to justify a causal conclusion.

Sample answer: Removing the tactile tool helps establish internal validity because it shows that the off-task behavior reverts back to baseline when the treatment is absent. This reversion demonstrates that the tactile tool, rather than an extraneous event (such as a change in classroom structure), was the cause of the decreased off-task behavior. To make this causal claim, the psychologist must assume that the tactile tool does not produce a permanent effect on the student's behavior; if it did, the behavior would not return to baseline, making it impossible to rule out extraneous variables.

Key points:

  • Withdrawing the tactile tool allows the researcher to see if the off-task behavior reverts to baseline levels.
  • Reversion of behavior upon treatment withdrawal helps rule out extraneous variables, establishing internal validity.
  • The psychologist must assume that the tactile tool does not create a permanent behavioral change.

Rubric: The answer must explain that withdrawing the tool establishes internal validity by showing behavioral reversion to baseline, which rules out extraneous variables. It must also identify the assumption that the tool's effects are temporary rather than permanent.

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Updated 2026-05-27

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Research Methods in Psychology - 4th American Edition @ KPU

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