Two Key Studies of Biological Theories of Altruism (DP IB Psychology)

Key study one: Simmons et al. (1977)

Aim: To test kin selection theory by investigating the extent to which close relatives of a kidney patient would be willing to offer themselves as kidney donors

Participants:

• An opportunity sample of potential kidney donors

• These donors were the relatives of existing kidney patients

• The sample was obtained from the records of University of Minnesota hospitals

Procedure:

• The participants were given questionnaires which asked them whether they would be willing to donate one of their kidneys to their close relative

• The close relative was an existing patient receiving treatment for a kidney condition

• The potential kidney recipients (the kidney patients) were asked to rate how emotionally close they felt to all of their possible donors (before the choice of a donor had been made)

Results:

The following table shows the results for agreeing to donate a kidney and the degree of closeness to potential donors/non-donors felt by the kidney patients:

Conclusion:

• Kin selection theory goes some way towards explaining prosocial behaviour from a biological/evolutionary perspective:

  • Those closest genetically to the patient were more willing to donate a kidney (86% agreement from the parents of kidney patients)

  • The drop to 47% for siblings also agrees with the theory as siblings are not as genetically close as parent and child  

Evaluation of Simmons et al. (1977)

Strengths

• The study used actual kidney patients who were awaiting kidney donation, which makes the ecological validity of the study high

• The results support the idea of altruism as an evolutionary mechanism as it makes evolutionary sense for a parent to sacrifice their own fitness to ensure that their offspring survives 

Limitations

• 14% of the parents in the sample did not agree to donate a kidney to their son/daughter:

  • this finding casts some doubt on the validity of the theory

  • if kin selection theory held true then 100% of parents should automatically agree to donate a kidney to their child

• There may be other factors determining the decision to donate a kidney, for example:

  • the siblings who agreed to donate were generally the same sex as the recipient, closer in age

  • the above finding means that these siblings probably had more in common with the recipient than with those who did not agree to donate

  • some potential donors who did not agree to donate may have had underlying health issues which precluded them from donating a kidney

  • some potential donors may have had a phobia of hospitals or surgery which is not a biological explanation of behaviour

  • some potential donors may simply not have felt very close or even liked the recipient which is not a biological explanation of behaviour

Key study two: Crockett et al. (2010)

Aim:

• To investigate if serotonin directly affects moral judgement by increasing the motivation of participants to help others and their aversion to personally harming others

• In tandem with the above aim: to investigate the role of serotonin in prosocial behaviour

Participants:

• 24 males from the Cambridge area of the UK with a mean age of 25.6 years

• The participants were screened for psychiatric and neurological disorders before the study began

Procedure:

• The participants were randomly assigned to one of the following three groups/conditions:

  • SSRI group: the participants were given the antidepressant citalopram, which works as a selective serotonin reuptake inhibitor and is regularly prescribed to treat depression

  • ADHD and OCD drug group: the participants were given a drug used to treat ADHD and OCD 

  • Placebo group: the participants were not given any sort of drug

• The drugs were administered using a double-blind procedure:

  • neither the participants nor the researchers knew which group each participant had been assigned to

• The first part of the procedure involved participants being asked to make moral judgements about a series of hypothetical scenarios, each of which was linked to one of the two conditions of the independent variable:

  • The emotionally salient ‘personal harm’ condition: 

    • Would you push someone in front of a train if it meant saving five other people? 

  • The emotionally salient ‘impersonal harms’ condition:

    • Would you flick a switch so that a train hit one person instead of five? This was the less  

• There was no time limit on how long the participants spent thinking about each scenario and making their decisions

• The responses were measured according to how many times each participant judged that an action was ‘acceptable’

Results:

• The emotionally salient personal harm condition (i.e. which involved participants imagining themselves harming someone else directly) produced the lowest number of ‘acceptable’ responses from all participants

  • in other words, participants could not agree to intervene personally to harm another person, even if it meant saving others

• Participants in the SSRI group were far more likely to say that harmful actions were unacceptable compared to the other two groups

• The moral judgements made by the ADHD/OCD drug group and the placebo group were roughly similar, showing no great differences

Conclusion: Serotonin may induce prosocial behaviour and reduce acts of harm towards others

Evaluation of Crockett et al. (2010)

Strengths

• The procedure involved a double-blind allocation of drugs and placebo, which increases the validity of the findings

  • it means that both researchers and participants did not know what drug was being taken, which should eliminate any bias

  • neither participants nor researchers could act in accordance with any expectations they might have had as to the effects of a drug

• The study used objective methods and a replicable, standardised procedure which increases the reliability of the findings

Limitations

• The small sample size of 24 males from Cambridge presents several issues:

  • 24 participants divided between 3 conditions, means that the results are not statistically robust

  • the results cannot easily be generalised to males outside of Cambridge

  • an all-male sample brings with it gender bias 

• There may be alternative explanations for the moral judgements made by the participants:

  • some of the participants may have held religious principles which would mean that they were predisposed to be prosocial 

  • some of the participants may have been in a better mood than others which would increase their inclination to be prosocial

  • some of the participants may have been presented with the same or similar moral dilemmas before which would bias their response to the scenarios