To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Movie S2. Latency to vocalize during novel object of a dog that was released from the program and a dog that was placed as a guide. Effects of maternal investment, temperament, and cognition on guide dog success Emily E. Bray, Mary D. Sammel, Dorothy L. Cheney, James A. Serpell, and Robert M. Seyfarth PNAS. 2017. 114:9128-9133 DOI: 10.1073/pnas.1704303114 Download Original Video Browse All Videos »