Is Spatial Memory Age-Related?

1. There is a commonly-held belief that it is more difficult for the Elderly than for the Young to learn and remember new material. It is possible that the Elderly have a reduced capacity to recall or retain learnt information, but there are alternative explanations that relate to the way in which they learn. For example the Elderly may use fewer, or less suitable, strategies for memorising the material, or they may be over-confident in their own abilities and so devote insufficient time to learning the material. Is Spatial Memory Age-Related?

2. In order to investigate spatial memory, a study was carried out on two groups of people, designated as Young (20-25) and Elderly (over 65). The trick is to see if you can answer the questions posed and write your conclusions in plain English? Is Spatial Memory Age-Related?

3. In the study, 18 labelled objects were arranged randomly on a 10 x 10 grid. Is Spatial Memory Age-Related?

4. Thirteen Young and fourteen Elderly subjects were allowed to examine the positions of the objects for as long as they liked and were subsequently asked to recall these positions by replacing the objects on the grid. Their study times and two measures of recall performance were recorded. Is Spatial Memory Age-Related?

5. The main objective is to compare the age groups. Is Spatial Memory Age-Related?

6. The city block score, attempts to account for near misses by measuring the distances (in “city blocks”, i.e. horizontal and vertical steps across the grid) between the actual and replaced positions, and totalling these over the 18 objects. Is Spatial Memory Age-Related? Skip to second lecture Skip to first test Skip to third lecture Skip to fourth lecture

7. The main objective is to compare the age groups. One particular topic that might arise here is the risk of confounding in the two group study because any differences seen between the Young and Elderly might be due not to their age differences but to difference(s) in some other variable(s). Is Spatial Memory Age-Related?

8. In this study the groups were, in fact, generally balanced in terms of sex ratio, IQ and educational experience, but this does not preclude the possibility that further, unsuspected, differences are present. Additionally, some people naturally tend to process information verbally, while others process information spatially or visually. Thus, a person who processes information verbally may score poorly in the spatial memory test although (s)he may have a generally good memory. Is Spatial Memory Age-Related?

9. We are going to use some basic graphs to explore the data, particularly to compare the results of the Elderly and Young groups. We shall first look at boxplots. Is Spatial Memory Age-Related?

10. Question - What can you tell about the scores achieved by the two age groups? To what extent do the scores for the two groups overlap? Comment on the median scores and the variation in scores within each group. Is Spatial Memory Age-Related?

11. Graphs > Legacy Dialogs > Boxplot Is Spatial Memory Age-Related?

12. Simple > Define Is Spatial Memory Age-Related?

13. ncorrect for the variables and agegroup for the Category Axis Is Spatial Memory Age-Related?

14. Finally Question - What can you tell about the scores achieved by the two age groups? To what extent do the scores for the two groups overlap? Comment on the median scores and the variation in scores within each group. Is Spatial Memory Age-Related?

15. Answer - On the whole Elderly subjects got fewer correct than the Young, with scores for the Elderly group overlapping the lowest quartile of scores achieved by Young subjects. Although scores for the Elderly were typically lower, the lowest scores achieved in each group were the same. One person, case number 5, in the Elderly group has been identified as an outlier. The scores for the Young were more spread out and most were over 10. Is Spatial Memory Age-Related?

16. Question - What do the boxplots tell you about the differences between the age groups in their city block scores? Remember that the city block score measures the errors made in positioning objects on the grid. Look at the medians, the Inter Quartile Ranges (IQR) and comment on the degree of overlap. Does the diagram show any outliers? Is Spatial Memory Age-Related?

17. cityblock for the variables and agegroup for the Category Axis Question - What do the boxplots tell you about the differences between the age groups in their city block scores? Look at the medians, the Inter Quartile Ranges (IQR) and comment on the degree of overlap. Does the diagram show any outliers? Is Spatial Memory Age-Related?

18. Answer - The median city block score is approximately 12 for the Young subjects and 27 for the Elderly. This means that generally the Young subjects were more accurate in placing the objects than the Elderly. The upper quartile for the Young subjects is about the same as the lower quartile for the Elderly subjects. This means that three quarters of Young subjects have city block scores similar to those of the lowest scoring (most accurate) quarter of the Elderly subjects. The IQR is similar for both groups and neither group has any outliers. Is Spatial Memory Age-Related?

19. Question - Now use boxplots to compare the study times of the two groups and comment on the results. Look at the same features as in the last two questions and also comment on the shape of each graph. Is Spatial Memory Age-Related?

20. time for the Variables and agegroup for the Category Axis Question - Now use boxplots to compare the study times of the two groups and comment on the results. Look at the same features as in the last two questions and also comment on the shape of each graph. Is Spatial Memory Age-Related?

21. Answer - Almost all of the Elderly subjects spent much less time on the task than Young subjects. The median study times are 42.5 seconds for Elderly subjects and 95 seconds for Young subjects. Both groups have a slight positive skew. Two Elderly subjects are shown as outliers as the result of taking longer than other subjects in the same group. Is Spatial Memory Age-Related?

22. Question - From the evidence above do you think that city block score or number correct is better as a measurement of memory? Is Spatial Memory Age-Related?

23. Answer - The number correct is a crude, but easy way of measuring spatial memory; it does not allow for “near-misses”. Comparing, for example, the two sets of boxplots, we see that comparing the Elderly and Young, the former do not get many repositions absolutely right. However, in the city block scores, although the Young group are generally better, some of the Elderly do just as well and some of the Young are just as poor as the Elderly. City block score seems to be a better method. Is Spatial Memory Age-Related?

24. In the next few questions we will look at some alternatives to the boxplots used above, to see whether other diagrams can be equally successful as a tool for showing the differences between groups. First try using stem and leaf plots. Is Spatial Memory Age-Related?

25. Question - What are the differences between the age groups in the number of correctly placed objects? How well do the diagrams allow you to make comparisons between the groups of subjects? Is Spatial Memory Age-Related?

26. Analyze > Descriptive Statistics > Explore Is Spatial Memory Age-Related?

27. Select ncorrect for the Dependent List box Select agegroup for the Factor List Is Spatial Memory Age-Related?

28. Finally number correct Stem-and-Leaf Plot for agegroup= Elderly Frequency Stem & Leaf 1.00 Extremes (=<5.0) 2.00 6 . 00 2.00 7 . 00 7.00 8 . 0000000 2.00 9 . 00 Stem width: 1 Each leaf: 1 case(s) number correct Stem-and-Leaf Plot for agegroup= Young Frequency Stem & Leaf .00 0 . 4.00 0 . 5799 8.00 1 . 01123444 1.00 1 . 6 Stem width: 10 Each leaf: 1 case(s) Is Spatial Memory Age-Related? 2*6 2*7 7*8 2*9 Question - What are the differences between the age groups in the number of correctly placed objects? How well do the diagrams allow you to make comparisons between the groups of subjects? 5,7,9,9 10,11,11,12,13,14,14,14 16

29. Answer - This is not a particularly helpful way to draw the data here as the diagrams for the two groups are not displayed side by side as they were in the boxplots. Also the ‘leaf’ for the Elderly consists of one unit where as each ‘leaf’ for the Young subjects covers 5 units. The boxplot shown below the stem and leaf diagram (and constructed earlier) is much clearer . Is Spatial Memory Age-Related?

30. Barcharts are helpful when we have discrete variables with not too many values. Is Spatial Memory Age-Related?

31. Question - Describe the distribution of the number of correctly replaced objects. What do you notice about the horizontal axis? Is Spatial Memory Age-Related?

32. Graphs > Legacy Dialogs > Bar Is Spatial Memory Age-Related?

33. Simple > Define Is Spatial Memory Age-Related?

34. Select ncorrect for the Category Axis and click on % of cases Is Spatial Memory Age-Related?

35. Finally Question - Describe the distribution of the number of correctly replaced objects. What do you notice about the horizontal axis? Is Spatial Memory Age-Related?

36. Answer - There were 18 objects to be correctly replaced on the grid; the highest score was 16 and the lowest 5. The most frequent number of objects replaced correctly (the mode) is 8. Only 9 of the 27 subjects, i.e. one third, replaced more than half correctly. The horizontal axis is in order but not drawn to scale – individual values are treated as categories, so that 14 and 16 are shown as adjacent values. Is Spatial Memory Age-Related?

37. A variation of this can help us to see the differences between the Elderly and Young groups. Question - What does this tell you about the distribution of the number correct in the two groups? Is Spatial Memory Age-Related?

38. Select Barchart as before then Stacked > Define Is Spatial Memory Age-Related?

39. Select ncorrect for the Category Axis and agegroup for the box labelled and Define Stacks by Under Bars Represent select % of cases Is Spatial Memory Age-Related?

40. Finally Question - What does this tell you about the distribution of the number correct in the two groups? Is Spatial Memory Age-Related?

41. Answer - All of those with more than half right were in the Young group. Scores for this group range from 5 to 16. The Elderly group’s scores range from 5 to 9, with half of the group scoring 8 correct. The stacked Barchart shows clearly that the Young are more successful than the Elderly in replacing the objects correctly. Is Spatial Memory Age-Related?

42. In the same way, draw barcharts for city block score for the two age groups. Is Spatial Memory Age-Related? Be careful to check how different scores and times are shown on the x-axis.

43. In the same way, draw barcharts for study time stacked for the two age groups. Is Spatial Memory Age-Related? Be careful to check how different scores and times are shown on the x-axis.

44. Question - Are these barcharts a good way of showing the differences between the age groups in city block scores and study times? Is Spatial Memory Age-Related?

45. Answer - Not really, as there are blocks for each value that may not be evenly spaced. Also the default graphs have rather too many bars. The graphs show that the Elderly generally take shorter study times than the Young but that their city block scores are generally poorer. Is Spatial Memory Age-Related?

46. Histograms are used to represent the frequency distributions of continuous variables. Is Spatial Memory Age-Related?

47. Question - Are study time or city block scores continuous variables? Is Spatial Memory Age-Related?

48. Answer - Time is usually regarded as a continuous variable. The city block score, being the sum of blocks in horizontal and vertical directions is a discrete variable. Is Spatial Memory Age-Related?

49. Question – How easy is it to compare the distribution of study time between the Young and Elderly groups? What is the main problem? Is Spatial Memory Age-Related?

50. Analyze > Descriptive Statistics > Explore Is Spatial Memory Age-Related?