suggests that the preload forces the dieters to cross their diet boundary and consequently
overeat. It has been suggested that this overeating may be related to lowered mood (either
as a result of the preload or independently) and/or changes in their cognitive state.
This study aimed to examine shifts in cognitive state following the consumption of a
‘forbidden food’ using self-report measures and the Stroop task.
Methodology
Subjects A total of 56 female subjects from a London university took part in the study
and were categorized as either restrained eaters or unrestrained eaters according to their
scores on the restrained eating section of the Dutch Eating Behaviour Questionnaire
(DEBQ) (van Strien et al. 1986). They ranged in age from 19 to 25 years and were of
average weight.
Design The subjects were randomly allocated to one of two conditions (low-calorie
preload versus high-calorie preload) and completed a set of rating scales and the Stroop
tasks before and after the preload.
Procedure After completing the rating scales and the Stroop tasks, the subjects were
given either a high-calorie preload (a chocolate bar) or a low-calorie preload (a cream
cracker). Subjects then completed the ratings scales and Stroop tasks again.
Measures The following measures were completed before and after the preload:
1 Stroop tasks. The original Stroop task (Stroop 1935) involved a repeated set of
colour names (e.g. ‘green’, ‘red’, ‘blue’, ‘black’) written on a card in different colour
inks (e.g. green, red, blue, black). Subjects were asked to name the colour of the ink
(not the word itself). For example, if the word ‘green’ was written in blue ink, the
subject should say ‘blue’. The time to complete the task was recorded and it was
argued that a longer time indicated greater interference of the meaning of the word.
Research has used the Stroop task to examine anxiety, phobias and post-traumatic
stress disorder using words such as ‘fear’, ‘anxiety’ and ‘panic’ instead of names
of colours. Subjects are still asked to name the colour of the ink and it has been
suggested that longer times infer that the words are more relevant to the individual’s
concerns. For example, an anxious subject would take longer to colour name
anxiety-related words than a non-anxious one. The present study used an adaptation
of the Stroop task to examine (1) ‘food’ words; (2) ‘body shape’ words and words
relating to the individual; and (3) cognitive state, in order to assess the effect of
preloading on the subjects’ processing of these words.
Food Stroop: the subjects were asked to colour name a set of food-related words
(e.g. dinner, cake, sugar), which were compared with a set of neutral words
matched for word length and frequency (e.g. record, powder, boot).
Body shape Stroop: the subjects colour named body shape words (e.g. chest, fat,
thigh) and matched neutral words (e.g. crowd, grass, rust).
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