hand bias (Hopkins, 1995). Absolute ... regardless of left or right hand (Hopkins, 1995). ... were previously held at Bucknell University (Caitlin Samuel, personal.
Talk To The Hand: Hamadryas Baboons (Papio hamadryas) Hand Preference in Gestural Communication Raymond Vagell Animal Behavior and Conservation Program, Department of Psychology, Hunter College
RESULTS
INTRODUCTION
DISCUSSION
This preliminary study sought to elucidate whether hamadryas baboons (Papio hamadryas) at the Prospect Park Zoo (WCS) in Brooklyn, New York exhibit hand preference in unimanual gestural communication by examining hand slap & muzzle wipe.
43% of P. hamadryas at the Prospect Park Zoo exhibit a right-hand preference for hand slap, which supports H1. Hand slap is the most lateralized: 3 baboons with maximum ABSHI of 1.0 and 1 baboon with ABS-HI of 0.9.
Hand slap: quick and repetitive rubbing or slapping of the hand on the ground, a sign of aggression. Muzzle wipe: self-directed spontaneous behavior where an individual touches its own muzzle, a sign of stress.
The absence of hand slapping in 2 baboons could be cultural. These females (Rebecca and Kaia) were known to not hand slap when they were previously held at Bucknell University (Caitlin Samuel, personal communication, 2014).
Predictions: Because the muzzle is in the middle of the face, we expect that there is no positional bias in hand preference. However, we do expect a hand preference in hand slapping. Hypotheses: H1: There is a hand preference for hand slap. H2: There is no hand preference for muzzle wipe.
Photo 2: Rebecca (muzzle wiping) and Bole
71% of P. hamadryas at the Prospect Park Zoo exhibit a right-hand preference for muzzle wipe., which does not support H2.
Hand Slap & Muzzle Wipe Handedness Index (HI) in P. hamadryas at Prospect Park Zoo
Muzzle wipe is the least lateralized: 4 baboons exhibited right-hand preference with the maximum ABS-HI of 0.4.
Rebecca Kaia
Although most baboons have a right-hand preference for muzzle wipe, the ABS-HI indicates that the strength is low.
Binti Matara Kobo
Photo 1: Simen, Bole, Kobo, Matara, Binti, Kaia and Rebecca
CONCLUSIONS
Simen Bole -1
METHODS Conducted between April 17th to May 4th, 2013. Observations were done at varying times between 12 PM to 5 PM using all occurrence sampling. Handedness Index (HI) & chi-squared tests (X2) for hand preference were tabulated for each subject.
Muzzle Wipe HI Hand Slap HI
-0.8
Bole 0.4 1
-0.6
-0.4
Simen 0.4 1
-0.2
Kobo 0 -1
0
Matara -0.1 0.9
0.2
0.4
Binti 0.2 0.1
0.6
Kaia 0.3 0
0.8
Rebecca 0.1 0
Figure 1: Bar graph showing hand slap and muzzle wipe handedness index (HI) of P. hamadryas at Prospect Park Zoo. Hand slap HI for all P. hamadryas is X2 (1, N = 5) = 17.04, p < 0.001 and muzzle wipe HI for all P. hamadryas is X2 (1, N = 7) = 10.50, p < 0.05.
HI = (R-L) ÷ (R+L); -1.0 ≥ HI ≤ 1.0 HI was used to characterize each subject’s hand preference based on a continuum of highly left-handed to highly right-handed. Positive HI reflects a right-hand bias; negative HI reflects a lefthand bias (Hopkins, 1995). Absolute value of handedness index (ABS-HI) reflects the strength of a subject’s hand preference regardless of left or right hand (Hopkins, 1995). Considered no left- or right-hand preference if -0.2 > HI < 0.2 (Hopkins, 2013).
RESEARCH POSTER PRESENTATION DESIGN © 2012
www.PosterPresentations.com
1
Name
Hand Slap (# of Occurrences)
Muzzle Wipe (# of Occurrences)
Bole
7
88
Simen
2
43
Kobo
1
22
Matara
21
87
Binti
15
60
Kaia
None
27
Rebecca
None
51
Table 1: Table showing the number of occurrences for hand slap and muzzle wipe of P. hamadryas at Prospect Park Zoo.
Results are consistent with previous studies on another baboon species, olive baboons (Papio anubis) (Vauclair et al., 2005; Meguerditchian & Vauclair, 2006; Meguerditchian & Vauclair, 2009). Results from this pilot study can contribute to the study of nonhuman primate handedness, as well as the evolution of human language.
REFERENCES Hopkins. 1995. J. of Comp Psych 109(3): 291 - 297. Hopkins. 2013. Am. J. of Physical Anthropology 151(1):151-7. Meguerditchian & Vauclair. 2006. Beh. Brain Research 171: 170 - 174. Meguerditchian & Vauclair. 2009. Brain & Language 108: 167 - 174. Vauclair et al. 2005. Brain Res Cogn Brain Res 25(1): 210 - 216.
ACKNOWLEDGEMENTS I would like to thank Dr. Scott Silver for his help in this study. Thanks to Terry Webb, the Prospect Park Zoo, as well as the hamadryas baboon troop for making this study possible. Scan this QR code for a copy of the poster
