The role of implicit attitudes towards food and ... - ResearchGate

44 M. Craeynest et al. / Eating Behaviors 9 (2008) 41–51
six months later (T2), and at follow up one year after completing the program (T3). Concerning T2, the participants
were not exactly tested at the end of their treatment, as this moment was different for each of them. Each time, height,
weight, implicit and self-reported attitudes were assessed. For practical reasons, the first measurement was completed
at the Department of Moving and Sports Science of Ghent University, whereas the second measurement was completed
in the residential setting. For the one year follow up, the children were invited to the residential setting for a general
check-up. Sixteen youngsters of the test group showed up. The other three were tested at home.
All children were tested individually. The order in which the two EASTs were administered, was counterbalanced.
The questionnaire was completed after both EASTs were conducted. Each EAST consisted of three different blocks.
Before each task, the participant provided words for physical activities or foods that he/she really (dis)liked. Next, in a
first practice block, these individually selected attribute words appeared randomly four times in a white colour on the
screen. Participants were instructed to classify these words according to their valence as quickly and as accurately as
possible, by pressing the m-(positive) or the q-(negative) key of an AZERTY keyboard, in order to learn an extrinsic
association between a positive (negative) valence, and the left (right) key. In a second practice block, each target
stimulus was presented in at least once in blue and once in green. In the food task 12 trials were presented, and in the
activity task 24 trials. Half of the participants pressed the m-key in response to green words and the q-key in response to
blue words; the others pressed the m-key in response to blue words and the q-key in response to green words. In this
way, they learned an association between a key carrying a valence and a colour. Finally, each task consisted of four
crucial test blocks in which a mix of target and attribute words were presented. The physical activity task contained four
test blocks of 32 trials (14 white trials, 18 coloured trials) each; the food task contained four test blocks of 38 trials each
(14 white trials and 24 coloured trials). The words had to be classified depending on valence (for white words) or colour
(for green and blue words). Stimuli were always presented in a random order, whereby the mixed blocks did not
necessarily alternate between target (coloured) and attribute (white) stimuli. The inter-trial interval was 400 ms. If the
participant responded incorrectly, a red cross appeared for 400 ms on the screen and the next stimulus was presented.
2.5. Statistical analyses
Analyses were carried out using SPSS 12.0 for Windows. The analyses of the EASTs took only the responses on the
coloured test trials into account, whereby trials with an incorrect response were discarded (De Houwer, 2003). In line
with Greenwald et al. (1998), reaction times (RTs) below 300 ms or above 3000 ms were recoded to 300 ms and
3000 ms respectively. All RTs were log-transformed. Also mean percentage of errors (PE) were analysed. On the selfreports,
attitudes towards sedentary activities, moderate intense physical activity (PA), high intense PA, unhealthy food
and healthy food were obtained by averaging the respective item scores. Evolutions in mean attitudes were calculated
conducting Repeated Measures ANOVA's. The explaining variance of attitudinal changes during treatment for the
decrease in overweight during treatment and at follow up was analyzed using covariate multiple regression analyses.
3. Results
3.1. Mean implicit and self-reported attitudes at baseline
A 3 (word category: sedentary activities vs. moderate intense PA vs. high intense PA)×2 (extrinsic response
valence: positive vs. negative) Repeated Measures ANOVA on the baseline reaction times of the physical activity task
showed no significant effects, all Fsb2.85. Also the same 3×2 Repeated Measures ANOVA conducted on the baseline
percentage of errors revealed no effects, all Fsb2.19. However, a 2 (word category: unhealthy vs. healthy food) ×2
(extrinsic response valence: positive vs. negative) Repeated Measures ANOVA on the baseline reaction times of the
food task showed a significant main effect of valence, F(1, 18)=6.08, pb.05. This indicates that the participants were
positive towards both healthy and unhealthy food, which was also found in the total group as described in Craeynest
et al. (2005). No other effects were found, all Fsb1. Also the same 2 ×2 Repeated Measure ANOVA conducted on the
percentage of errors, revealed no effects, all Fsb2.49. A three-level within factor (word category: sedentary activities
vs. moderate intense vs. high intense PA) Repeated Measures ANOVA on the self-reported attitudes towards physical
activity, showed a significant effect, F(2, 17)=5.54, pb.05. Post hoc paired sample t-tests showed that moderate
intense PA was rated more positive than sedentary activities, t(18) =3.08, pb.01, and high intense PA, t(18) =2.61,
pb.05. A two-level within factor (word category: unhealthy vs. healthy food) Repeated Measures ANOVA on the