The objective of this study was to determine if diet influences behavioral responsiveness to novel stimuli as assessed by human approach (HAT) and novel object tests (NOT). Eighty Yorkshire barrows were fed a high fiber, low energy diet or a low fiber, high energy diet. Testing occurred over four consecutive weeks between 1300 and 1700 h. Barrows were tested individually within a 4.9 x 2.4 m test arena. Throughout the test, zone activity, escape attempts, freezing, urination, and defecation behaviors were recorded. The results suggest that dietary fiber reduces overall activity and may modify fear responsiveness while undergoing human approach and novel object tests in swine.