Lewinsohn et al. (1990) - MDD Sociocultural Explanations - (the Behavioural explanation)

Lewinsohn et al. (1990) - Aim:

To compare the amount of positive reinforcement received by patients with MDD and non-depressed participants.

Lewinsohn et al. (1990) - Procedure:

30 patients with MDD, a disorder other than depression and a control group of people who did not have MDD i.e. this was a quasi experiment.

Participants were asked to complete questionnaires conducted daily over a 30-day period which required them to give a self-rating of mood using a depression adjective checklist e.g. ‘I feel lucky/active/happy/miserable/gloomy/dull today’ etc. They were also asked to fill in a ‘Pleasant activities’ schedule on a daily basis over the same 30-day period, which involved scheduling and participating in positive activities aimed to boost mood and encourage feelings of wellbeing. Positive reinforcement was operationalised as the key determinant of whether the pleasant activities were a) enjoyed and b) repeated (i.e. each pleasant activity was rated twice by participants on a scale of 0-3, one scale for enjoyment and one scale for repetition)

Lewinsohn et al. (1990) - Results:

Positive correlations (which were statistically significant) were found between rating of mood and number of pleasant activities engaged in i.e. the more pleasant activities a participant was involved in, the higher was their mood rating.

Lewinsohn et al. (1990) - Conclusion:

There may be a link between the positive reinforcement derived from pleasant activities and mood (specifically good mood, feeling upbeat and optimistic).

Lewinsohn et al. (1990) - Evaluation:

Strengths:

- The use of standardised questionnaires, rating scales and correlational analysis means that the study has some degree of reliability

- The longitudinal design of the study means that the participants were able to track their mood mapped to pleasant activities in real time which increases the validity of the findings

Weaknesses:

- The participants may have succumbed to social desirability bias, providing responses which cast them in the best light (this can happen on an unconscious level which makes it particularly difficult to factor out)

- The researchers reported that they found significant individual differences in the participants’ responses which affects the validity of the findings as it leaves unanswered questions as to what it is about pleasant activities specifically that boosts mood