To learn more about chimpanzees’ helping behaviour.
To find out:
• whether they can understand the needs of conspecifics.
• whether they respond to those needs with targeted helping.
Humans offer targeted helping, and animals help after a direct request from the conspecific. The ability to offer targeted help is linked to the theory of mind. Some say only humans can offer targeted helping however, recent studies have shown primates to offer altruistic helping. Targeted helping is help given based on the cognitive understanding of the situation of others. There is some evidence that chimpanzees engage in targeted helping.
Research Method, Design and Variables
Research Method: A lab experiment.
Research Design: Repeated measures design was implemented.
Independent Variable: the ability of the chimpanzee to give targeted help in 2 situations:
• Can see the tool use task of the recipient chimpanzee.
• Cannot see.
Dependent Variable: targeted helping behaviour (stick or straw)
Socially housed chimpanzees at the Primate Research Institute, Kyoto University. Previously taken part in perceptual/cognitive studies including helping behaviour similar to the present study’s settings. 5 chimpanzees: Ai, Ayumu, Pan, Pal, Cleo. They were familiar with the tool use task, tested and cared for in accordance with the Animal Care Committee. The opportunity sampling technique was used.
• Ai (mom) with Ayumu (child)
• Pan (mom) with Pal (child)
• Chloe (mom) with Cleo (child)
The helper chimpanzee had to offer the recipient chimpanzee the correct tool. 1 task required a stick and the other straw. The recipient chimpanzee obtained a reward: a juice box. There were 7 objects in the helping chimpanzee’s tray: stick, straw, belt, chain, brush, hose, string. First, the chimpanzee did condition 1 (can see). Next, the chimpanzee did condition 2 (cannot see). Then, they repeated condition 1 (can see) to check for order effects.
There were 48 trials carried out in each condition. 24-stick use and 24 straw-use trials were randomly ordered. There were 2 – 4 trials per day. A trial starts when the tray was presented to the helper chimpanzee. A trial ends when the recipient succeeded in obtaining the juice box or when 5 minutes had passed without receiving an object.
‘Offers’ were counted when chimpanzees held out objects regardless of if whether the recipients took them. Only the first offer was counted. Participant’s behaviours were recorded using 3 cameras.
1. Upon request offer: a tool is offered when the recipient requests. A request was when the recipient poked an arm through the hole.
2. Voluntary offer: help is actively offered without the recipient’s explicit request.
3. No offer: the tools are taken away without an offer.
Object offer is when chimpanzees offer any object which may be right or wrong. 'Tool' is the correct object given. 'Non-tools' are any other objects given.
Can See Condition
1. Object offer = 90% of trials. In the familiarisation phase, object offer was 5%. 'Upon request offer' accounted for 90% of all offers.
2. Except for Pan, sticks and straws were significantly more frequently offered the non-tools (78% - 97.4%). Pan most frequently offered non-tool, brush, which may be due to past experience.
3. Chimpanzees demonstrated flexible targeted helping depending on their partner's tool-use situation.
Cannot See Condition
1. Object offer = 90% of trials. Upon request offer accounted for 71.7% of all offers.
2. Cleo showed a significant increase in offering help in the 'cannot see condition' and this may be due to a carryover effect. This increased voluntary offer as the helper learned that they are expected to offer an object to their partner.
3. Stick/straw was not offered more than the non-tools. Except Ayumu did as he kept peeking through the hole. This shows that chimpanzees understood their partner’s goals only when they could see.
2nd Can See Condition: 3 chimpanzees who had shown a significant decrease in tool selection in the first condition and a non-significant decrease in the cannot see condition were used.
1. Object offer observed for 98% of trials. Upon request offer for 79% of all offers.
2. Significant decrease in the offer of stick/straw depending on the partner’s situation. This confirms that flexible targeted helping with an understanding of the tool need to complete the task was possible when chimpanzees could see the task for themselves.
1. Chimpanzees will help conspecifics in most cases, but usually as a response to a direct request rather than voluntarily.
2. Chimpanzees rely on visual confirmation of conspecific needs in order to offer targeted helping.
Strengths and Weaknesses
- High level of controls and standardised procedures increased reliability. Objects on the tray were the same for all trials, and chimpanzees sat at the same booth.
- Repeated measures design reduced the risk of individual differences affecting the study and increased validity.
- Lack of ecological validity as they were in artificial settings. Chimpanzees were also given tasks/ tools they would not normally use in the natural environment. However, as they were socially housed, they probably showed their natural behaviour so, we can say that the study is valid.
- We cannot conclude that the correct tool offered is an intentional cognitive decision as it could be an automatic assumption from previous experience. Pan had repeatedly offered the brush because her experience with previous similar tasks created a bias in her response.
- There were only 5 chimpanzees, and they were from the same Research Institute thus, we can see that the sample was very small and low in generalizability. Also, captive chimpanzees are not identically representative of the wild chimpanzees.
- Chimpanzee Ayumu had shown demand characteristics by peeking through the hole to understand the task.
It helps us understand more about chimpanzee societies, and we now know that chimpanzees have the capacity to help conspecifics.
Individual vs Situational Explanation to Behaviour
Most chimpanzees showed similar patterns of behaviour. However, the influence of individual personalities was seen when Pan showed a preference for the brush and Ayumu peeked through the hole.