Unconscious local motion alters global image speed.

Accurate motion perception of self and object speed is crucial for successful interaction in the world. The context in which we make such speed judgments has a profound effect on their accuracy. Misperceptions of motion speed caused by the context can have drastic consequences in real world situations, but they also reveal much about the underlying mechanisms of motion perception. Here we show that motion signals suppressed from awareness can warp simultaneous conscious speed perception. In Experiment 1, we measured global speed discrimination thresholds using an annulus of 8 local Gabor elements. We show that physically removing local elements from the array attenuated global speed discrimination. However, removing awareness of the local elements only had a small effect on speed discrimination. That is, unconscious local motion elements contributed to global conscious speed perception. In Experiment 2 we measured the global speed of the moving Gabor patterns, when half the elements moved at different speeds. We show that global speed averaging occurred regardless of whether local elements were removed from awareness, such that the speed of invisible elements continued to be averaged together with the visible elements to determine the global speed. These data suggest that contextual motion signals outside of awareness can both boost and affect our experience of motion speed, and suggest that such pooling of motion signals occurs before the conscious extraction of the surround motion speed.

A randomized, double-blind, placebo-controlled trial of venlafaxine for the treatment of depressed cocaine-dependent patients.

OBJECTIVE: This study tested the hypothesis that the antidepressant venlafaxine would be an effective treatment for cocaine abusers with concurrent depressive disorders. METHODS: This was a randomized, 12-week, double-blind, placebo-controlled trial of outpatients (N = 130) meeting DSM-IIIR criteria for cocaine dependence and major depression or dysthymia (by SCID interview). Participants were treated with venlafaxine, up to 300 mg/day versus placebo. All patients received weekly individual manual-guided relapse prevention therapy. Weekly outcome measures included Clinical Global Impression Scale (CGI), self-reported cocaine use, urine toxicology and the Hamilton Depression Scale (Ham-D). RESULTS: Mood response, defined as a 50% reduction in the Ham-D between randomization and end of study, was 41% (26/64) on venlafaxine, and 33% (22/66) on placebo (p = .39). Measures of depression (Ham-D and CGI) improved more rapidly on venlafaxine than placebo, but these differences disappeared by weeks 6-8. Cocaine outcomes did not differ between treatment groups, and the proportion of patients achieving three or more consecutive weeks of urine-confirmed abstinence was low (venlafaxine: 16%; placebo: 15%). Reduction in cocaine use was associated with mood response. CONCLUSIONS: Overall, venlafaxine was not superior to placebo on either mood or cocaine use outcomes. Mood improvement was associated with improvement in cocaine use. However, placebo mood response was only moderate, and the proportion of patients achieving sustained abstinence was low. This suggests that the subgroup of cocaine-dependent patients with depressive disorders is relatively treatment resistant, and that further research is needed to improve outcomes for these patients.