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Kea show no evidence of inequity aversion

View Article: PubMed Central - PubMed

ABSTRACT

It has been suggested that inequity aversion is a mechanism that evolved in humans to maximize the pay-offs from engaging in cooperative tasks and to foster long-term cooperative relationships between unrelated individuals. In support of this, evidence of inequity aversion in nonhuman animals has typically been found in species that, like humans, live in complex social groups and demonstrate cooperative behaviours. We examined inequity aversion in the kea (Nestor notabilis), which lives in social groups but does not appear to demonstrate wild cooperative behaviours, using a classic token exchange paradigm. We compared the number of successful exchanges and the number of abandoned trials in each condition and found no evidence of an aversion to inequitable outcomes when there was a difference between reward quality or working effort required between actor and partner. We also found no evidence of inequity aversion when the subject received no reward while their partner received a low-value reward.

No MeSH data available.


Related in: MedlinePlus

Box plots showing the average number of time actors successfully exchanged the token with the experimenter for each condition (out of a maximum of 50 trials). Boxes represent the interquartile range, lines within boxes represent median values and whiskers represent the 5th and 95th percentiles.
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RSOS160461F2: Box plots showing the average number of time actors successfully exchanged the token with the experimenter for each condition (out of a maximum of 50 trials). Boxes represent the interquartile range, lines within boxes represent median values and whiskers represent the 5th and 95th percentiles.

Mentions: A non-parametric Friedman's test were then conducted to examine whether there was a difference between the baseline equity test and the two no reward conditions (partner absent and partner present). A significant difference was found between these conditions (χ2 = 6.53, p = 0.38), suggesting that token exchanges dropped significantly between the baseline equity test and one or both of the no reward conditions (NRPA and NRIC, figure 2). We then ran a Wilcoxon signed-rank test between the two no reward conditions to analyse whether the drop in exchanges was due to subjects witnessing their partner receive a reward while they received nothing or whether it was simply due to not receiving a reward themselves. No significant difference between the number of successful exchanges was found (Z = −0.535 p = 0.593). Therefore, the fact that subjects did not receive a reward themselves, regardless of whether they witnessed their partner receive a reward, explains why performance significantly dropped in these conditions.Figure 2.


Kea show no evidence of inequity aversion
Box plots showing the average number of time actors successfully exchanged the token with the experimenter for each condition (out of a maximum of 50 trials). Boxes represent the interquartile range, lines within boxes represent median values and whiskers represent the 5th and 95th percentiles.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383808&req=5

RSOS160461F2: Box plots showing the average number of time actors successfully exchanged the token with the experimenter for each condition (out of a maximum of 50 trials). Boxes represent the interquartile range, lines within boxes represent median values and whiskers represent the 5th and 95th percentiles.
Mentions: A non-parametric Friedman's test were then conducted to examine whether there was a difference between the baseline equity test and the two no reward conditions (partner absent and partner present). A significant difference was found between these conditions (χ2 = 6.53, p = 0.38), suggesting that token exchanges dropped significantly between the baseline equity test and one or both of the no reward conditions (NRPA and NRIC, figure 2). We then ran a Wilcoxon signed-rank test between the two no reward conditions to analyse whether the drop in exchanges was due to subjects witnessing their partner receive a reward while they received nothing or whether it was simply due to not receiving a reward themselves. No significant difference between the number of successful exchanges was found (Z = −0.535 p = 0.593). Therefore, the fact that subjects did not receive a reward themselves, regardless of whether they witnessed their partner receive a reward, explains why performance significantly dropped in these conditions.Figure 2.

View Article: PubMed Central - PubMed

ABSTRACT

It has been suggested that inequity aversion is a mechanism that evolved in humans to maximize the pay-offs from engaging in cooperative tasks and to foster long-term cooperative relationships between unrelated individuals. In support of this, evidence of inequity aversion in nonhuman animals has typically been found in species that, like humans, live in complex social groups and demonstrate cooperative behaviours. We examined inequity aversion in the kea (Nestor notabilis), which lives in social groups but does not appear to demonstrate wild cooperative behaviours, using a classic token exchange paradigm. We compared the number of successful exchanges and the number of abandoned trials in each condition and found no evidence of an aversion to inequitable outcomes when there was a difference between reward quality or working effort required between actor and partner. We also found no evidence of inequity aversion when the subject received no reward while their partner received a low-value reward.

No MeSH data available.


Related in: MedlinePlus