Cotton- Top Tamarin (IMAGE) Association for Psychological Science Caption tamarin grasping the stem of a plastic champagne glass to pull the glass from the apparatus in order to extract a marshmallow stuck inside the glass. In (a), the monkey exhibits the thumb-up grasp orientation, and in (b), the monkey exhibits the thumb-down grasp orientation. Credit Dan Weiss Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.