THC reduces their 'willingness to exert cognitive effort,' even for a larger reward
                                
                                
                                    (Newser) -
                                    Scientists, apparently bored with pert, productive rats, added a little marijuana to the equation and found that, as many a teenager can tell you, laziness ensued. So report researchers at the  University of British Columbia  in the  Journal of Psychiatry and Neuroscience  after concluding that male lab rats given TCH...