Two Key Studies of Cognitive Biases: Hamilton & Gifford (1976) & Piliavin et al. (1969) (DP IB Psychology)

Key Study: Hamilton & Gifford (1976)

Aim: To investigate illusory correlation as a cognitive bias

Participants: 40 undergraduate students from a university in New York state, USA (20 males; 20 females)

Procedure: 

• The participants were presented with two hypothetical groups - i.e. these were not real groups consisting of real people with given characteristics. The participants were told that Group A consisted of 26 members and that Group B consisted of 13 members

• The participants then read a series of statements which each described a particular behaviour performed by either a member of A or B e.g. John, a member of A, visited a friend in hospital

• The behaviours described in the statements were classified as either desirable or undesirable. Both A and B were assigned more positive than negative behaviours at a ratio of 9:4 (positive to negative) and two thirds of the statements overall were attributed to members of A

• Thus, members of A were presented as performing more behaviours overall than B and positive behaviours were more frequent from both groups than negative behaviours

The participants were then asked to provide ratings for the following measures: 

1. Given a list of 20 attributes, assign each to either group A or B

2. Given a particular example of a behaviour, say whether this behaviour was performed by a member of A or B

3. Estimate how many negative behaviours can be attributed to either A or B

Results: The mean scores showed that participants attributed more desirable social behaviours (6.7) to members of Group A than to members of Group B (6.0); undesirable social behaviours were attributed more to Group B (5.6) than to Group A (4.4)

Conclusion: The results suggest that illusory correlation may be based on group size: the smaller group, B, appears more distinctive than the larger group A so that any undesirable behaviours are linked more often to the minority group, B, than to the majority group A. This has implications in terms of how minority groups are viewed by society

Evaluation of Hamilton & Gifford (1976)

Strengths

• The measures (rating scales) used in the study could be cross-referenced by the researchers to check for consistency across them which should ensure both reliability and internal validity

• The findings could be used to inform awareness-raising as a means to reduce prejudice and increase tolerance of minority groups

Weaknesses

• The procedure does not fully reflect how people respond in real-life situations where they are exposed to minority groups which reduces ecological validity

• The study is rather simplistic in its use of statements about hypothetical people and situations which makes it difficult to draw very meaningful conclusions from the findings

Key terms:

• Illusory correlation

• Minority

• Majority

Key Study: Piliavin et al. (1969)

Aim: To investigate the degree of help given to a victim who appeared to be either drunk or disabled

Participants: A field experiment which used an opportunity sample of 4,450 passengers (55% white; 45% black) using the New York subway between Harlem and The Bronx during the hours of 11am until 3pm over the course of several months. The journey lasted 7.5 minutes without any stops 

Procedure:

• A staged (fake) procedure which was conducted inside one carriage of the aforementioned Harlem/Bronx subway route. 4 confederates were used: 2 females as observers, 1 white male aged 24 – 29 to model helping behaviour and 1 male victim aged 26 – 35 (either white or black, dressed identically; the ‘drunk’ victim smelled of alcohol and the ‘cane’ victim had a cane to indicate that he was disabled) 

• 103 trials were conducted by alternating teams of researchers over the total course of the research’s duration

• The female confederates took seats and kept notes, while the male victim and male model stood near a pole in the centre of the train

• After passing the first station (approximately 70 seconds into the journey) the victim collapsed

• In the “no help” condition, the model did nothing until the train slowed to a stop, and then helped the victim to his feet

• In the “helping” condition, the model came to the victim’s assistance

• The collapse occurred in what the researchers referred to as the critical area which was in the immediate vicinity of the victim

There were four different helping conditions used in both “drunk” and “cane” situations:

1. Critical area early: the model stood in the critical area and waited approximately 70 seconds after the collapse to help

2. Critical area late: the model stood in the critical area and waited approximately 150 seconds after the collapse to help

3. Adjacent area early: the model stood a little further way, adjacent to the critical area and waited approximately 70 seconds after the collapse then helped the victim

4. Adjacent area late: the model stood a little further way, adjacent to the critical area and waited approximately 150 seconds after the collapse then helped the victim

Results: The victim in the ‘cane’ condition received spontaneous help on 95% of the trials (62 out of 65 times) - i.e. there was very little need for the model to help first; people helped the apparently disabled man immediately upon his collapse. The ‘drunk’ condition received help on 50% of the trials (19 out of 38 times)

Conclusion: The results support the Just-World Hypothesis as the victim in the ‘cane’ condition was helped 50% more than the victim who appeared to be drunk. It is possible that 

people operate a system of judgement when deciding who to give help to - i.e. does the victim ‘deserve’ help or not?

Evaluation of Piliavin et al. (1969)

Strengths

• The study is high in ecological validity due to the use of the natural setting and unartificial behaviour of the naïve participants

• The use of two observers should ensure inter-rater reliability

Weaknesses

• The procedure is likely to have been affected by a range of extraneous variables that were impossible to control e.g. individual differences such as personality and mood; some of the participants experiencing the procedure more than once if they used that route regularly; participants in the carriage obscuring the view of the observers

• The ethics of the study are problematic: no informed consent; deception of participants; possible psychological harm; no right to withdraw or debriefing 

Key terms:

• Just-World hypothesis

• Field experiment

• Confederates