The aim

1. The aim was to test whether size perception depends on remembered familiar size or on visual distance information.

Procedure

1. In experiment one, 109 male undergraduates estimated the heights of 50 familiar objects from memory, with nothing present to look at, returning the questionnaire within 48 hours.
2. In experiment two, 9 male students were walked through the empty fourth quadrant of a field to its centre, where each of the other three quadrants held 15 objects.
3. One quadrant held familiar token-invariant objects, which have a narrow size range, such as a bowling ball.
4. Another held familiar token-variant objects, which have a wide size range, such as a Christmas tree, and the third held unknown painted cardboard shapes.
5. Each participant estimated the size and the distance of every object.

Results

1. Size estimates were accurate, and they became less accurate as token variance rose, with standard deviations of 0.00 to 0.08 for token-invariant objects against 0.36 to 1.26 for token-variant ones.
2. Perceived size estimates, made with the objects in view, and remembered size estimates, made from memory alone, were equally accurate.
3. Distance information did not improve size estimates.
4. Distance estimates were significantly worse for the token-variant objects than for the token-invariant ones, and worse again for the unknown objects.

Conclusion

1. Size perception draws on memory and prior knowledge of the object, which is a top-down influence.
2. Distance perception draws on the environment instead.
3. Size and distance perception are therefore relatively independent of each other, which is what the study is used to support.

Strengths of the study

1. A strength is that experiment two used a real outdoor three-dimensional setting rather than a picture or a screen, so the judgements were made in the kind of space they are meant to describe.
2. A second strength is that experiment one gives a memory-only baseline matching the size task in experiment two, so the claim that remembered and perceived sizes were equally accurate rests on a fair comparison.

Weaknesses of the study

1. A weakness is that the samples in both experiments were all male, so nothing in the results tells you whether women judge size and distance in the same way.
2. A second weakness is that experiment two used only 9 participants, which makes it risky to treat the pattern as true of people in general.

Turning this into marks

1. Give the precise figures, such as 109 male undergraduates and 9 male students, because a vague phrase such as some students earns nothing.
2. Say which half of the findings you are using, since size leaning on stored knowledge and distance coming from the environment point in different directions.
3. The mark most often lost is describing the two procedures with no evaluation attached to them.