Pain and Pessimism: Dairy Calves Exhibit Negative Judgement Bias following Hot-Iron Disbudding Neave, Heather W. ; Daros, Rolnei R. ; Costa, João H. C. ; von Keyserlingk, Marina A. G. ; Weary, Daniel M. Abstract Publication: PLoS ONE Pub Date: December 2013 DOI: 10.1371/journal.pone.0080556 Bibcode: 2013PLoSO...880556N