Table 1.
Means, Standard Deviations, and Effect Sizes for Main Effects of Expectancy and Drug Manipulations for Credibility and Subjective Measures
| Instructed |
Received |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| THC |
Placebo |
THC |
Placebo |
|||||||
| Measure | M | SD | M | SD | Effect size | M | SD | M | SD | Effect size |
| Credibility ratings | ||||||||||
| Taste | 2.03 | 1.42 | 0.80 | 1.03 | .33* | 1.83 | 1.41 | 1.00 | 1.25 | .20 |
| Smell | 2.60 | 1.07 | 1.4 | 0.97 | .30* | 2.30 | 0.95 | 1.70 | 1.34 | .10 |
| Similar to usual | 1.45 | 1.26 | 1.10 | 1.20 | .02 | 1.65 | 1.16 | 0.90 | 1.20 | .10 |
| Potency | 2.50 | 1.18 | 1.40 | 1.17 | .47** | 2.90 | 0.74 | 1.00 | 0.94 | .73*** |
| THC content | 1.80 | 0.63 | 0.80 | 0.92 | .61*** | 1.90 | 0.57 | 0.70 | 0.82 | .69*** |
| Number of puffs | 9.70 | 1.70 | 17.0 | 6.70 | .42** | 12.8 | 4.24 | 13.9 | 7.67 | .02 |
| Subjective effects | ||||||||||
| Satisfaction | 2.30 | 1.06 | 1.40 | 1.65 | .21 | 2.80 | 1.13 | 0.90 | 0.99 | .54*** |
| Liking | 2.45 | 1.12 | 1.80 | 1.23 | .17 | 2.95 | 0.90 | 1.30 | 0.82 | .56*** |
| Makes feel better | 1.75 | 1.23 | 1.30 | 1.34 | .05 | 2.25 | 1.09 | 0.80 | 1.03 | .36** |
| SAM arousal | 3.70 | 0.86 | 2.85 | 1.11 | .09a | 3.05 | 0.90 | 3.50 | 1.20 | .04 |
| ARCI–M scale T1 | 5.10 | 3.11 | 4.60 | 3.83 | .003a | 6.90 | 3.28 | 2.80 | 2.10 | .31** |
| ARCI–M scale T2 | 4.60 | 3.44 | 4.10 | 3.41 | .004a | 6.80 | 2.70 | 1.90 | 1.73 | .50*** |
Note. THC = delta-9-tetrahydrocannabinol; SAM = Self-Assessment Manikin; ARCI–M scale = Addiction Research Center Inventory—Marijuana scale; T1 = immediately postsmoking; T2 = 45 min postsmoking.
a
Effect size is indicated as sr2 from regression analyses controlling for baseline values; all other effects in the table are partial η2 from two-way (Expected × Received) analyses of variance.
*
p < .05.
**
p < .01.
***
p < .001.