Nuevo medio, nuevos elementos

The present study was designed as an investigation of the role of implicit food attitudes in eating behaviour and sub-clinical ED symptomatology. Previous research carried out in restrained eaters suggests (albeit not unequivocally) that both restrained and unrestrained eaters hold positive associations with high-fat, compared to low-fat food (Roefs, Herman, MacLeod, Smulders, & Jansen, 2005; Roefs et al., 2005; Hoefling & Strack, 2008; Veenstra & de Jong, 2010; Houben, Roefs, & Jansen, 2010). Additionally, findings from studies in ego depletion suggest that when self-control resources are drained, people are more likely to behave

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The present study is aimed at linking these two bodies of research. By their definitions (as discussed earlier in this chapter), both dietary restriction and dietary restraint constitute acts of self-control: the former being an act of physical self-regulation, with the latter also including its cognitive aspects. The classic cookie/radish paradigm is an empirical demonstration of restriction resulting in ego depletion under laboratory conditions. However, it can also be hypothesised that people who chronically engage in dietary restriction and/or restraint will likewise be in a chronic state of elevated ego depletion. The current study therefore examines a) differences in implicit food attitudes in elevated ED pathology, and b) differences in the effects of restraint-based ego depletion. This study was designed for a sub-clinical population, but with the intention of adapting it to a clinical context in the future.

5.1. RESEARCH AIMS AND HYPOTHESES

 Hypothesis 1: Both high- and low-pathology participants will hold positive implicit

associations with high-fat food. The present study is unique in using the IAT to

specifically assess implicit associations between food and palatability. This hypothesis is formulated to confirm that positive implicit associations with high-fat food are near- universal in non-clinical samples, as the subsequent hypotheses are predicated on this assumption. Palatability was chosen as the valence variable in the IAT on the

assumption that impulsive eating behaviour is driven by a short-term hedonic reward goal. The analyses pertaining to this hypothesis will also be repeated with the EDE-Q Restraint sub-scale as the dependent variable, in order to isolate any differences in implicit attitudes which may be specific to differences in dietary restriction/restraint.

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 Hypothesis 2: There will be no significant differences in implicit attitudes between high-

and low-pathology participants. Research has previously examined implicit food

attitude differences between restrained and unrestrained eaters (Papies, Stroebe, & Aarts, 2009; Veenstra & de Jong, 2010; Houben et al., 2010), obese and normal weight participants (Roefs & Jansen, 2002; Roefs et al., 2005) and in fasting and non-fasting participants (Hoefling & Strack, 2008). The present study is the first with a focus on the relationship between implicit attitudes and sub-clinical ED pathology. Analyses using the EDE-Q Restraint subscale will be conducted to eliminate the possibility that restriction and/or restraint affect implicit food attitudes.

 Hypothesis 3: Participants scoring high on restriction and/or restraint will exhibit higher

levels of disinhibition on an ego depletion task (i.e., will give up faster), following dietary restraint compared to those who score low. If Hypotheses 1 and 2 are

confirmed, Hypothesis 3 is designed to address whether chronically elevated restriction/restraint can affect the extent of ego depletion following a restriction episode. This hypothesis also extends to differences between high- and low-pathology participants, in line with the previous hypotheses.

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6. Method

6.1. PARTICIPANTS

Thirty-nine female undergraduates took part in the study. Three participants failed to attend the second session and were therefore excluded from the analyses. Six participants failed to meet the minimum accuracy criterion on the IAT (>80%, see Study 1) and were therefore also excluded. Two more participants could not complete the IAT due to equipment failure. The final sample therefore consisted of 28 participants. Sample size calculations using a medium effect size (.40, based on results obtained in the following ego depletion studies: Baumeister, Bratslavsky, Muraven, & Tice, 1998; Friese et al., 2008; Hofmann et al., 2007) and assuming a repeated measures, within-between ANOVA, indicated a suggested sample size of N=20, which is lower than the actual sample size obtained. Participants’ mean age was 24.79 (SD=8.87) and mean BMI, calculated from self-reported height and weight, was 20.85 (SD=2.71), which is towards the lower end of the healthy weight range (BMI 18.5-25).

Participants were categorised as high- or low-pathology via a median split on the basis of Global EDE-Q scores. The median-split approach was used because no formal conventions exist with regards to cut-off points on the EDE-Q for levels of pathology which is not clinically significant. Median splits, as well as arbitrary cut-off points, have also been used in other studies within this research area using non-clinical participant samples (Hoefling & Strack, 2008; Roefs et al., 2005; Houben et al., 2010). Participants in the high-pathology group (N=14) scored an average of 2.22 (SD=.73) on the EDE-Q overall, while low-pathology participants (N=14) scored 0.57 (SD=.37), t(26)=7.471, p=.015. The clinically significant cut-off for the EDE-Q is 2.3 (Mond et al., 2004); 42.9% of participants in the high-pathology group scored above this threshold, although none reported a formal ED diagnosis. High- and low-pathology participants did not differ in age, F(1,26)=.051, p=.824, or BMI, F(1,26)=.1.036, p=.318. They did, however, differ significantly on all four sub-scales of the EDE-Q (see Table 3).

The aspects of the hypotheses specific to the Restraint subscale were similarly addressed using a median split, with participants scoring above the median (.80) classified as “high

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restraint” (N=17), and those scoring below as “low restraint” (N=11). These labels were selected for parsimony, although it must be reminded that the Restraint subscale of the EDE-Q may reflect aspects of both restriction and restraint. However, as the current study is interested in any dietary behaviour which constitutes self-control, it was not essential to use a “pure” measure of either restriction or restraint, as both restriction and restraint involve self control. The high- and low-restraint groups differed significantly in restraint, t(26)=5.281, p<.000, but not in age, t(26)=-.015, p=.988, or BMI, t(26)=21.753, p=.603.

Table 3

Subscale score differences on the EDE-Q1 _{by group} High Pathology (N=14) Low Pathology (N=14) F η2_p EDE-Q Restraint 1.96 (1.05) .51 (.69) 18.58 .417

EDE-Q Weight concern 2.47 (1.17) .66 (.68) 25.13 .491

EDE-Q Shape concern 3.08 (.85) .82 (.73) 20.66 .443

EDE-Q Eating concern 1.38 (.84) .29 (.31) 56.79 .686

1 _{EDE-Q: Eating Disorders Examination Questionnaire}