Table 1.
Performance differences in the temporal processing tasks between SDI and control subjects with education controlled for as a covariate.
| Temporal processing tasks | Stimulant-dependent individuals | Control subjects | F
df = 27 |
p |
|---|---|---|---|---|
| Mean | Mean | |||
| Duration discrimination | ||||
| Weber fraction Δt / t | ||||
| 100 ms | .440 | .315 | .361 | .553 |
| 1000 ms | .183 | .118 | 9.292 | .0025* |
| Temporal reproduction | ||||
| Mean reproduced interval [θ] | ||||
| 1000 ms | 1.016 | 1.076 | 2.440 | .075 |
| 2000 ms | .912 | 1.014 | 9.500 | .0025* |
| 3000 ms | .908 | .947 | .433 | .251 |
| 4000 ms | .827 | .916 | 1.311 | .131 |
| 5000 ms | .804 | .871 | .463 | .250 |
| CV reproduced interval | ||||
| 1000 ms | 21.6 | 11.3 | 10.531 | .0015* |
| 2000 ms | 15.9 | 8.6 | 2.364 | .075 |
| 3000 ms | 11.0 | 8.2 | 2.064 | .081 |
| 4000 ms | 11.3 | 7.4 | 1.186 | .143 |
| 5000 ms | 13.4 | 8.7 | 4.318 | .023 |
|
| ||||
| Sensorimotor Synchronization | ||||
| Mean Asynchrony [ms] | ||||
| 1000 ms | 2.60 | −34.0 | .159 | .346 |
| 2000 ms | −40.3 | −51.4 | 1.340 | .129 |
| 4000 ms | −169.8 | −144.8 | .275 | .303 |
| Missed synchronizations [%] | ||||
| 1000 ms | 17.4% | 9.5% | .065 | .400 |
| 2000 ms | 32.4% | 27.6% | .267 | .305 |
| 4000 ms | 60.6% | 46.3% | .144 | .303 |
|
| ||||
| Continuation Tapping | ||||
| Mean inter-tap interval [θ] | ||||
| 1000 ms | .938 | 1.036 | 5.497 | .0135* |
| 2000 ms | .960 | .991 | .309 | .291 |
| 4000 ms | .961 | 1.025 | .810 | .188 |
| CV inter-tap interval | ||||
| 1000 ms | 6.2 | 4.7 | 4.299 | .024 |
| 2000 ms | 7.6 | 4.9 | 7.605 | .005* |
| 4000 ms | 5.5 | 5.4 | .055 | .996 |
|
| ||||
| Time estimation (53 sec interval) | ||||
| Mean estimate [θ] | 1.513 | 1.122 | 3.984 | .0253* |
*
significant difference with initial alpha level of .05. Bonferroni-adjusted for multiple tests (duration discrimination: p < 0.025, temporal reproduction: p < 0.001, sensorimotor synchronization and continuation tapping: p < 0.0167, time estimation: p < 0.05)