Table 1.

Descriptive Statistics for all Measures

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.