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. Author manuscript; available in PMC: 2015 Mar 1.
Published in final edited form as: Anim Cogn. 2013 Jun 18;17(2):197–205. doi: 10.1007/s10071-013-0652-9

Table 2.

Yerkes chimpanzees

a. Choice part
Inter-item interval for accumulation
3s (Phase 1) 10s (Phase 2) 20s (Phase 3)

% choice of 12 items binomial test (n = 30) % choice of 12 items binomial test (n = 30) % choice of 12 items binomial test (n = 30)

Artemus 73 p = .016 80 p = .001 63 p = .200
Brandy 60 p = .362 63 p = .200 57 p = .585
Brodies 67 p = .099 53 p = .856 53 p = .856
Callie 57 p = .585 67 p = .099 57 p = .585
Cissie 93 p < .001 77 p = .005 93 p < .001
Davids 53 p = .856 53 p = .856 63 p = .200
Edwinas 60 p = .362 60 p = .362 53 p = .856
Fayes 60 p = .362 57 p = .585 50 p = 1.000
Foxy 70 p = .043 47 p = .856 77 p = .005
Frannie 53 p = .856 60 p = .362 57 p = .585
Julie 60 p = .362 73 p = .016 70 p = .043
Katrinas 73 p = .016 53 p = .856 63 p = .200
Melissa 63 p = .200 67 p = .099 47 p = .856
Socratess 73 p = .016 67 p = .099 50 p = 1.000
Sylvia 60 p = .362 63 p = .200 57 p = .585
b. Accumulation part
Inter-item interval for accumulation
3s (Phase 1) 10s (Phase 2) 20s (Phase 3)

mean items one-sample t test mean items one-sample t test mean items one-sample t test

Artemus 11.55 t(21) = 16.60*** 10.57 t(23) = 17.41*** 5.42 t(18) = 1.74ns
Brandy 11.72 t(17) = 27.80*** 9.05 t(18) = 17.28*** 2.88 t(16) = −2.38od
Brodie 11.10 t(19) = 11.46*** 11.56 t(15) = 37.17*** 5.81 t(15) = 1.43ns
Callie 12.00 N/A 12.00 N/A 10.06 t(16) = 5.78***
Cissie 11.46 t(27) = 23.70*** 8.78 t(22) = 5.48*** 6.00 t(27) = 2.90**
David 11.50 t(15) = 15.0*** 9.51 t(15) = 16.01*** 8.63 t(18) = 5.29***
Edwina 11.11 t(17) = 11.66*** 9.83 t(17) = 5.87*** 6.94 t(15) = 2.30*
Faye 11.72 t(17) = 27.80*** 12.00 N/A 11.40 t(14) = 18.50***
Foxy 5.24 t(20) = 1.14ns 2.14 t(13) = −7.32od 2.35 t(22) = −4.91od
Frannie 9.07 t(14) = 4.26** 2.50 t(17) = −2.28od 1.00 N/A
Julie 12.00 N/A 11.95 t(21) = 175.0*** 11.10 t(20) = 11.73***
Katrina 11.95 t(21) = 175.0*** 11.88 t(15) = 92.22*** 11.95 t(18) = 151***
Melissa 12.00 N/A 10.05 t(19) = 8.67*** 7.60 t(14) = 3.96**
Socrates 11.00 t(21) = 10.14*** 6.95 t(19) = 3.69** 2.80 t(14) = −2.17od
Sylvia 9.28 t(17) = 8.44*** 2.89 t(18) = −5.50od 1.94 t(16) = −6.80od

Note:

s

exhibited a side bias in > 70% of trials;

***

p < .001;

**

p < .01;

*

p < .05;

ns

not significant;

od

significant in the opposite direction; N/A = not applicable (a t-test could not be conducted due to zero variance); italicized = failed to choose 12 items over 4 items in a post-hoc quantity judgment test