AP®PsychologyCollege BoardExam QuestionsResearch MethodsExperiments: Types & Design

Experiments: Types & Design (College Board AP® Psychology): Exam Questions

2 mins2 questions
1
1 mark

A researcher investigated how accurately people judge the distance of objects using different types of depth cues. Forty participants were tested individually in a controlled room. In one condition, participants used only monocular cues (one eye covered) to estimate the distance of objects placed at six different distances (0.5 m, 1 m, 2 m, 5 m, 10 m, and 20 m).

In a second condition, the same participants used binocular cues (both eyes open) to estimate the same distances. All participants completed the monocular condition first and the binocular condition second. The graph below shows the mean estimation error (in meters) for each condition at each distance. Lower error scores indicate more accurate distance judgments.

Line graph comparing mean estimation error in metres for binocular and monocular cues across object distances from 0.5 to 20 metres.

A colleague reviewing the study notes that all participants completed the monocular condition before the binocular condition. She argues that participants may have improved through practice or become fatigued, which could have systematically influenced the results.

Which of the following changes to the research design would most directly address the colleague's concern?

  • Increasing the number of distance intervals tested

  • Using a larger and more diverse sample of participants

  • Randomly assigning participants to either the monocular or binocular condition only

  • Having half the participants complete the monocular condition first and the other half complete the binocular condition first

Choose your answer

2
1 mark

A clinical psychologist assessed eight patients diagnosed with posttraumatic stress disorder (PTSD) before and after a 12-week course of trauma-focused therapy. Symptom severity was measured using a validated 80-point scale at the start and end of treatment, where higher scores indicate more severe symptoms.

The data are shown in the table below. The psychologist did not use a control group or randomly assign patients to conditions.

Patient

Pre-therapy score

Post-therapy score

1

61

42

2

55

38

3

53

44

4

49

31

5

44

28

6

42

35

7

38

22

8

38

19

The psychologist reports that all eight patients showed a reduction in symptom scores following therapy and concludes that trauma-focused therapy causes a reduction in PTSD symptom severity.

Which of the following most accurately describes a flaw in this conclusion?

  • Because there was no control group and no random assignment, it cannot be established that therapy caused the reduction in symptoms

  • The mean symptom score is not an appropriate measure for evaluating treatment effectiveness in clinical studies

  • The sample size of eight patients is sufficient to generalise the findings to all individuals diagnosed with PTSD globally

  • The validated symptom scale cannot measure PTSD severity because the disorder involves subjective experience

Choose your answer