Table 1.
Measure | Mean | SD | Range | Skew | Kurtosis |
---|---|---|---|---|---|
Processing Speed | |||||
Symbol Search | 41.09 | 6.80 | 39 | −0.09 | 0.57 |
Digit Symbol Coding | 88.25 | 13.27 | 75 | −0.00 | 0.62 |
Primary Memory | |||||
PM N-back | 8.73 | 1.15 | 6.50 | −1.41 | 3.13 |
Working Memory | |||||
Operation Span | 44.15 | 15.54 | 68 | −0.03 | −0.52 |
Listening Span | 29.77 | 12.22 | 67 | 1.075 | 1.63 |
WM N-back | 4.15 | 2.07 | 9.50 | .19 | −0.67 |
Secondary Memory | |||||
Story Recall | 13.86 | 3.24 | 15.5 | −.11 | −.64 |
Verbal Paired Assoc. I | 22.97 | 5.95 | 28 | −1.04 | .98 |
Family Pictures I | 51.36 | 7.44 | 40 | −1.31 | 2.10 |
Fluid Intelligence | |||||
Raven’s | 25.50 | 4.04 | 19 | −0.22 | 0.04 |
Block Design | 45.79 | 10.94 | 52 | −0.10 | −0.67 |
Matrix Reasoning | 19.89 | 2.92 | 17 | −0.94 | 1.72 |
Note: N = 172 for all measures. Raw scores were used for the measures from the WAIS-III (processing speed) and the WMS-III (secondary memory), while weighted summary scores were used for the laboratory measures of working memory. The N-back task was divided into two components, the Primary Memory N-back measure includes the average of the raw scores for lags 0 and 1, while the Working Memory N-back includes the average of the raw scores for lags 2 and 3. Story Recall represents the average of the total number of items recalled from the first two stories in the WMS-III test, Logical Memory I. Verbal Paired Assoc. I represents the total score from the four recall trials of the WMS-III test. Fluid intelligence was represented by a combination of measures from the WAIS-III, in which raw scores were used, and the Raven’s, for which the total score was used.