Table 1.
Neuropsychological Measures.
| Measure | Description1 | Reference2 |
|---|---|---|
| Executive Functions | ||
| Response inhibition | ||
| CPT commission errors | Commission errors on an 18 minutes CPT that requires the participant to respond whenever a 1 is immediately followed by a 9. | 49 |
| Stop-signal Task | A computerized task is used to calculate stop-signal reaction time (SSRT), a measure of speed of inhibitory control. | 51 |
| Vigilance | ||
| CPT omission errors | Omission errors on an 18 minute CPT task. | 49 |
| Interference Control | ||
| Stroop | An interference-control score was operationalized by subtracting the mean z-score on Word and Color naming trials from the z-score on an Interference trial containing both word and color information. | 48 |
| Set-shifting | ||
| Wisconsin Card Sorting Test | Sort cards based on one of three possible rules, then switch to a new sorting rule after feedback. The dependent variable is total perseverative errors (sorting to the previous rule after a rule change). | 50 |
| Trailmaking Test, Part B | Total time to connect a series of circles containing numbers and letters in ascending order, alternating between numbers and letters (i.e., 1, A, 2, B, 3, C,…). | 54 |
| Working Memory | ||
| WISC-R Digit Span | In the first half the participant repeats verbatim a series of numbers presented by the examiner. The second half requires the participant to repeat the numbers in reverse order. | 39 |
| Counting Span | The participant counts aloud the number of yellow dots on a series of cards, then is asked to recall, in order, the number of yellow dots that appeared on each of the cards in the set. | 44 |
| Sentence Span | The participant provides the last word for a set of simple sentences read by the examiner, then reproduces the words that they said in order after each set is completed. | 56 |
| Spatial Working Memory | The dependent variable was total errors on the spatial working memory subtest of the Cambridge Neuropsychological Test Automated Battery (CANTAB). | 52 |
| Time Estimation | A light is presented on a computer monitor for 1, 4, 8, 12, or 20 seconds, after which the participant attempts to hold down the space bar for the same period of time that the light was illuminated. The primary dependent measure is the mean absolute value of the difference between the time estimated by the participant and the time that the light was actually on. | 43 |
| Processing Speed | ||
| WISC-R Coding | This subtest requires the participant to rapidly copy symbols associated with specific digits based on a key provided. | 39 |
| WISC-III Symbol Search | The participant matches a symbol to an identical target that is displayed among several distracter stimuli that share some physical features | 58 |
| Rapid Automatized Naming | In each of the four trials the participant names as many depictions of objects, colors, numbers, and letters as possible in fifteen seconds. | 47 |
| Perceptual Speed Composite | Scores on the Educational Testing Service Identical Pictures test and Colorado Perceptual Speed, two widely-used tests that require speeded visual perception, were combined to create a Perceptual Speed Composite score. | 45, 46, 55 |
| Response Variability | ||
| Stop-signal Go trial RT SD | Standard deviation of reaction time on the Go trials of the stop-signal task. | 51 |
| Motivation/Delay Aversion | ||
| The Doors Task | On each trial the participant sees the image of a closed door on the screen, and is asked to decide whether they wish to open the door or stop the game and keep the money they have earned. If the participant opens the door they either win or lose $0.25. Participants win on nine of the first 10 trials, then the proportion of winning trials declines steadily. The primary dependent measure is the number of trials completed. | 53 |
| Delay Aversion | The participant chooses between a small reward ($0.25) after a two second delay and a larger reward ($0.50) provided after a 30 second delay. The task includes 20 trials no matter which reward is selected on each trial. | 57 |
1
inhibition, interference, working memory, and set-shifting tasks are described in detail by Willcutt et al. (2005b), processing speed tasks are described by Shanahan et al. (2006).
2
Numbers indicate references: 1.43. Barkley et al., 1997; 2.44. Case et al., 1982; 3.45. Decker, 1989; 4.46. DeFries, et al., 1978; 5. 47. Denckla and Rudel, 1976; 6.48. Golden, 1978; 7. 49. Gordon, 1983; 8. 50. Heaton, 1981; 9.51. Logan et al., 1997, 10.52. Owen et al., 1996, 11.53. Quay, 1988, 12. 54. Reitan & Wolfson, 1985; 13.55 Shankweiler, et al., 1979; 14.56 Siegel & Ryan, 1989; 15.57. Solanto et al., 2001, 16.39. Wechsler, 1974, 17.58. Wechsler, 1991.