Marsh et al

What was the aim of Marsh et al.’s study?

To examine potential biological origins of prosocial behaviour.

What research method did Marsh et al. use?

A quasi-experimental design.

Who composed the experimental sample in Marsh et al.’s study?

19 people who had donated a kidney to a stranger (extraordinary altruists).

How were altruistic participants recruited?

Through national mailings and electronic advertisements.

How many control participants were included?

20 control participants.

How were the control participants matched to the altruists?

They were matched for IQ, income, education, psychological history, and medication use.

What was the first stage of Marsh et al.’s procedure?

An fMRI emotion recognition task using 120 facial images expressing six basic emotions at varying intensities.

What behavioural measure was recorded during the emotion recognition task?

Reaction time when identifying emotional expressions.

What was the second stage of the procedure?

An MRI scan to measure brain structure and volume.

What was the third stage of the procedure?

Assessments of psychopathy and empathy levels.

What were the main results of Marsh et al.’s study?

Extraordinary altruists showed greater average volume in the right amygdala compared to controls.

What additional finding was observed in response to fearful faces?

Altruists had faster right amygdala activation and quicker reaction times to fear expressions.

Which brain hemisphere was implicated in altruistic behaviour?

The right hemisphere.

What role does the right hemisphere play according to the study?

It is involved in expressing and processing fear and fear‑inducing stimuli.

What conclusion did Marsh et al. draw?

There may be a biological basis for altruistic behaviour linked to amygdala structure and function.

What is one strength of Marsh et al.’s study?

High internal validity through method triangulation combining fMRI, MRI, and behavioural data.

How does method triangulation strengthen validity?

It increases confidence by corroborating findings across different types of measures.

What is one main limitation of Marsh et al.’s study?

Possible low internal validity due to fMRI artifacts caused by anxiety within the scanner environment.

Why could fMRI scanning conditions affect results?

Anxiety or stress from the environment may cause extra amygdala activation unrelated to task stimuli.

What is another limitation of Marsh et al.’s explanation of altruism?

It is reductionist, focusing mainly on biological factors while ignoring psychological and social influences.

What key implication does Marsh et al.’s study have for understanding altruism?

Extraordinary altruism may have a neurobiological component linked to amygdala structure and function.