Dietary Restraint and the Selective Processing of Forbidden and ...

Cognitive Therapy and Research, Vol. 21, No. 6, 1997 pp. 633-646

Dietary Restraint and the Selective Processing of Forbidden and Nonforbidden Food Words1 Judith A. Francis, Sherry H. Stewart,2 and Shelley Hounsell Dalhousie University

The present study examined whether restrained eaters relative to nonrestrained eaters show greater preoccupation with forbidden foods than nonforbidden foods using a modified Stroop color-naming task. Fourteen restrained eaters and 14 nonrestrained eaters completed a computerized Stroop task, involving naming the ink color of forbidden food words, nonforbidden food words, and animal control words. Subjects also rated all food words on perceived "forbiddenness" (degree to which subjects were avoiding each food in efforts to control body weight). As hypothesized, Stroop interference for both types of food words was greater for restrained eaters than nonrestrained eaters. Contrary to hypothesis, restrained eaters did not demonstrate greater interference when color naming forbidden versus nonforbidden food words. However, restrained eaters rated only forbidden foods as more highly forbidden than nonrestrained eaters. The finding that dietary restraint was associated with the selective processing of both forbidden and nonforbidden food words may suggest that restrained eaters are more preoccupied with both types of foods than nonrestrained eaters. Alternatively, the Stroop may tap differences in the personal relevance of food cues between restrained eaters and nonrestrained eaters occurring early in the information processing chain, prior to restrained eaters' later classification of food words as bad versus good (forbidden vs. nonforbidden).

1

Preparation of this manuscript was supported by a Social Sciences and Humanities Research Council of Canada Grant and Dalhousie University Clinical Psychology Program Start-Up Funds awarded to the second author. The first author is supported by a Dalhousie Graduate Student Fellowship. This study was conducted by the first and third authors, under the supervision of the second author. 2 Address all correspondence to Sherry H. Stewart, Department of Psychology, Dalhousie University, Life Sciences Centre, 1355 Oxford Street, Halifax, Nova Scotia B3H 4J1, Canada.

633 0147-5916/97/1200-0633$12.50/0 © 1997 Plenum Publishing Corporation

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Francis, Stewart, and Hounsell

KEY WORDS: dietary restraint; information processing; cognitive assessment; Stroop task; chronic dieting.

Restricting food intake is associated with an increased preoccupation with food and eating (Polivy & Herman, 1985; Wardle, 1987). Experimental studies suggest that dieting causes this increased preoccupation with food. Franklin, Schiele, Brozek, and Keys (1948) subjected 36 young men to a semistarvation diet (1,570 calories per day) for a period of 6 months. As the starvation period progressed, the men became increasingly preoccupied with food. In another study, Warren and Cooper (1988) placed seven men and seven women on a calorie-restricted diet (1,200 calories a day for women and 1,500 calories a day for men) for a period of 2 weeks. Subjects reported an increased preoccupation with food at the end of the 2-week period. While such research has provided valuable information on the cognitive consequences of dieting, a limitation is the reliance on self-reports which may be subject to reporting biases or error. More recently, researchers have utilized modifications of the traditional Stroop (1935) colornaming task as a more direct measure of cognitive processing in women with clinically diagnosed eating disorders as well as in normal weight dieters (see Fairburn, Cooper, Cooper, McKenna, & Anastasiades, 1991). Delayed latency (or interference) in color naming food words has been demonstrated repeatedly in women diagnosed with eating disorders. For example, Channon, Hemsley, and de Silva (1988) found that anorexic women took longer to color name food words than did non-eating-disordered female controls. Similarly, Ben-Tovim, Walker, Fok, and Yap (1989) found that anorexic and bulimic women took longer to color name food words versus control words than non-eating-disordered female controls. There is accumulating evidence to suggest that the selective processing of food words is not limited to women with diagnosed eating disorders. Perpina, Hemsley, Treasure, and de Silva (1993) found that bulimics and anorexics, as well as non-eating-disordered women who scored high in dietary restraint on the Restraint Scale (Herman & Polivy, 1980) took longer to color name food words than did nonrestrained controls. Similarly, Green and Rogers (1993) found that subjects high in dietary restraint, as measured by the Dutch Eating Behavior Questionnaire (van Strien, Frijters, Bergers, & Defares, 1986), took longer to color name food words relative to control words than did subjects low in dietary restraint, regardless of subjects' current dieting status. Stewart and Samoluk (1997) found that university students high in dietary restraint on the Restraint Scale (Herman & Polivy, 1980) took longer to color name food words than control words, whereas

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low dietary restraint controls showed no color-naming speed differences for these two types of cues. Interference in color naming food words has also been observed in non-eating-disordered subjects who fasted for 24 hours (Channon & Hayward, 1990). Results of this prior research with the Stroop task suggest that dietary restraint is associated with changes in the cognitive processing of food cues. It has been suggested that the observed slowing in color naming food words among high-restraint and eating disordered subjects reflects an increased preoccupation with food and eating (Channon et al., 1988). At present, however, the mechanism responsible for this increased food preoccupation is unclear. It is clear that behaviors related to dieting encourage an increased cognitive focus on food. Dieters are encouraged to pay strict attention to the quantity and types of foods they eat. Dieters start to make distinctions between different types of foods which are not made by nondieters. It has been well documented that women with eating disorders (Wardle, 1987) as well as highly restrained college students (Knight & Boland, 1989; Polivy & Herman, 1985) tend to classify foods as either good or bad, that is, either "forbidden" or "nonforbidden" in their diets. Forbidden foods tend to be high-fat, calorie-dense foods. Knight and Boland asked college students to classify 149 common foods as forbidden and nonforbidden and found a significant positive correlation between subjects' Restraint Scale scores and the number of foods rated as forbidden. Dieting also involves alternating these periods of intense focus on food with periods of attempted avoidance and abstinence. There is evidence that the act of trying to avoid a substance may actually lead to an increased preoccupation with that substance. Gross, Jarvik, and Rosenblatt (1993) examined the relationship between nicotine abstinence and Stroop interference for smoking-related words. They found that smokers who had been abstinent for 24 hours took longer to color name smoking related words than did nonabstinent smokers. The authors concluded that the abstinent smokers were more preoccupied with thoughts related to smoking than were nonabstinent smokers. If the act of attempting to avoid a substance is indeed associated with an increased preoccupation with the substance, this may explain restrained eaters' greater food interference on the Stroop relative to nonrestrained eaters, since restrained eaters try to avoid food in their efforts to prevent weight gain. Moreover, it seems possible that restrained eaters may be more preoccupied with thoughts of forbidden foods than nonforbidden foods. By definition, forbidden foods are foods that restrained eaters attempt to avoid most, in their efforts to control their body weight (Knight & Boland, 1989). The purpose of the present study was to determine whether restrained eaters relative to nonrestrained eaters show greater preoccupation with

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thoughts of forbidden foods than nonforbidden foods using the modified Stroop task. To date, no study has compared Stroop interference for forbidden foods versus nonforbidden foods among restrained eaters. Previous research investigating food preoccupation in restrained eaters using the modified Stroop task has either used entirely forbidden food words (e.g., Mahamedi & Heatherton, 1993, Study 2; Stewart & Samoluk, 1997) or has combined both forbidden and nonforbidden foods into a single category (e.g., Channon et al., 1988). In the present study, restrained eaters and nonrestrained eaters were asked to color name forbidden food words, forbidden food control words, nonforbidden food words, and nonforbidden food control words. It was hypothesized that: (a) restrained eaters would show more interference for both types of food words than nonrestrained eaters because restrained eaters are more conscious of the types and amounts of all foods that they eat, and (b) restrained eaters would show more interference for forbidden foods than nonforbidden foods because forbidden foods are those which restrained eaters attempt to avoid most (Knight & Boland, 1989).

METHOD Subjects Twenty-eight female students enrolled in an introductory psychology course at Dalhousie University served as subjects. Subjects were selected on the basis of scores obtained on the Restraint Scale (Herman & Polivy, 1980) during an initial prescreening held approximately 3 months prior to testing. Subjects were classified as restrained eaters (n = 14) if they obtained restraint scores of 16 or above at the time of prescreening and at the time of testing, and classified as nonrestrained eaters (n = 14) if restraint scores were below 16 on both occasions (Heatherton, Herman, Polivy, King, & McGree, 1988).

Materials Stroop Task. The Stroop task consisted of 15 forbidden food words (e.g., chips, icing), 15 nonforbidden food words (e.g., celery, carrots), and 30 control words. Forbidden and nonforbidden food words were chosen on the basis of Knight and Boland's (1989) research assessing the degree to which a variety of foods are perceived as forbidden when one is dieting. Each food word was matched with an animal control word for length of


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Table I. Frequencies of Usage and Word Length for Forbidden Foods, Nonforbidden Foods, and Control Words Forbidden foods Icing Pastry Chips Cake Candies Pizza Bacon

Pie Chocolate Sugar Butter Cream Cookie Cereal Puddings Mean (SD) Nonforbidden foods Celery Carrots Asparagus Tomatoes Mushroom Cantaloupe Rice Onions Salad Broccoli Peas

Egg Soup Cherry Potato Mean (SD)

Frequency

Word length

1 4 3 13 2 3 10 14 9 34 27 20 1 17 1

5 6 5 4 7 5 5 3 9 5 6 5 6 6 8

10.60 (10.27)

5.67 (1.50)

Frequency

Word length

4 4 1 3 2 1 33 4 9 1 24 12 16 6 15

6 7 9 8 8 10 4 6 5 8 4 3 4 6 6

9.00 (9.47)

6.27 (2.05)

Control words Frequency Camel Ponies Geese Deer Peacock Mules Mouse

Hen Elephants Bears Snakes Sheep Coyote Insect Crocodile

1 6 3 13 2 3 10 22 10 1 26 23 1 14 1

5 6 5 4 7 5 5 3 9 5 6 5 6 6 9

9.07 (8.80)

5.73 (1.62)

Control words Frequency Falcon Dolphins Anteater Cricket Armadillo Butterfly Bird Wolves Seals Squirrel

Cat Hawk Cows Chicks Buffalo

Word length

Word length

4 4 1 3 2 2 31 4 4 1 23 14 16 1 16

6 8 8 7 9 9 4 6 5 8 3 4 4 6 7

8.40 (9.35)

6.27 (1.94)

word (number of letters) and frequency of usage based on English language norms established by Kucera and Francis (1967). Thus control words for forbidden food words and nonforbidden food words were chosen from a single semantic category as recommended by Green and Rogers (1993). Care was taken to choose animal control words that did not immediately suggest food (see Table I), as this could decrease the likelihood of finding significant Stoop interference effects for the food words in the restrained eaters. All four categories were balanced for length and frequency. For-

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bidden food words, nonforbidden food words, and their respective control words are indicated in Table I, along with the mean length and frequency of usage for each word type. The Stroop task was presented on an IBM compatible 386 computer. A Realistic Highball-7 microphone and a voice onset relay device were connected to the computer to record subjects' vocal responses. As soon as a subject responded, the voice onset relay device sent the voice signal to the computer, which immediately stopped the clock on the computer timer. Color-naming latencies (i.e., the amount of time that elapsed between the onset of the stimulus word on the screen and the onset of the subject's vocal response) were measured to the nearest millisecond for each word. Self-Report Questionnaires. Subjects completed a modified version of the Food Evaluation Questionnaire (Knight & Boland, 1989) which asked subjects to rate on 9-point Likert scales the degree to which each of the foods presented in the Stroop task was forbidden for them. Endpoints of the scale were 1 (dietarily permitted) and 9 (dietarily forbidden). The definition of "forbidden" provided at the top of the questionnaire was "foods which you avoid in an effort to control body weight," which represented a departure from the definition provided to subjects by Knight and Boland (i.e., "foods that you believe should be avoided on a weight reduction diet"). This questionnaire was included as a manipulation check to ensure that subjects classified as "restrained eaters" were in fact attempting to avoid the foods used in the Stroop task "forbidden food" category to a greater extent than subjects classified as "nonrestrained eaters." Subjects also completed the Shipley (1940) Vocabulary Test, which served as a control measure of verbal knowledge, and the Restraint Scale (Herman & Polivy, 1980), which assesses a combination of dietary restraint—attempts to restrict food intake due to concerns about body weight—and dietary disinhibition—as reflected by history of body weight fluctuations (see Heatherton et al., 1988, for a review of the excellent psychometric properties of the Restraint Scale). Subjects were asked to indicate their current height and weight, which were used in the calculation of the Body Mass Index. Procedure

Subjects were tested individually. They were seated on a stool 2.1 m from the computer screen with their eyes level with the center of the screen. They were asked to color name each word as quickly as possible while ignoring the meaning of the word. Subjects were asked to speak into a microphone set on the table in front of them.


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Subjects were initially presented with 20 practice trials during which they were asked to color name a variety of words which were neutral in semantic content (e.g., one, two, three; McNally, Riemann, Louro, Lukach, & Kim, 1992). The color naming task consisted of two experimental trial blocks. Each food word and its control were presented once within each block. The order of word presentation was randomized with the constraint that no more than two words from the same category occurred in succession. Each trial began with a white fixation cross presented for 0.5 s in the center of a black computer screen (McNally et al., 1992). The stimulus word appeared 1.5 seconds later and was presented in one of four colors (red, green, pink, blue; Stewart, Conrod, Gignac, & Pihl, in press). The order of color presentation was randomized with the constraint that the same color could not appear more than twice in a row. The stimulus words appeared in upper-case block letters (11 x 14 mm) and remained on the screen for 1.5 s each. The intertrial interval was 5.5 s (Stewart et al., in press). The experimenter, who was seated behind the subject, recorded any errors in color naming. After completing the color-naming task, subjects were asked to complete, in the following order, the Restraint Scale, information on their current weight and height, the modified Food Evaluation Questionnaire, and the Shipley Vocabulary Test. Subjects received partial course credit for their participation.

RESULTS Subject Characteristics Body Mass Index (BMI) was calculated for each subject by dividing weight (in kilograms) by height (in meters) squared. Mean BMI for the entire sample was 22.43 (SD = 2.94). Mean Shipley (1940) Vocabulary test score was 28.07 (SD = 6.31). Results of separate t-tests revealed no restraint group differences on these control variables. The mean Restraint Scale scores for the restrained versus nonrestrained eaters were 21.43 (SD = 2.98) versus 8.57 (SD = 4.64), respectively. Modified Food Evaluation Questionnaire Subject ratings of the forbiddenness of Stroop food words on the modified Food Evaluation Questionnaire (Knight & Boland, 1989) were

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analyzed in a 2 x 2 repeated-measures analysis of variance (ANOVA). Group (restrained or nonrestrained) was a between subjects variable; food type (forbidden or nonforbidden) was a within subjects variable. Mean forbiddenness ratings for the food words are indicated in Table II, as functions of group and food type. Significant main effects of group, F(1, 26) = 15.14, p < .001, and food type F(1, 26) = 129.26, p < .0001, were found. Subjects rated forbidden foods as more forbidden than nonforbidden foods (see Table II), indicating a successful manipulation of the food type variable. Overall, restrained eaters rated the foods as more forbidden than nonrestrained eaters (see Table II). These main effects were qualified by a significant two-way interaction between group and food type, F(1, 26) = 15.86, p < .001. Results of t-tests indicated that restrained eaters and nonrestrained eaters did not differ significantly in their ratings of the forbiddenness of non-forbidden foods, t(26) = -1.28, n.s. However, restrained eaters rated forbidden foods as more forbidden than nonrestrained eaters, t(26) = -4.09, p < .001 (see Table II). Stroop Interference Preliminary examination of the Stroop color-naming latencies suggested that, consistent with previous work with obese subjects (Rodin, 1973; Rodin, Herman, & Schachter, 1974), restrained eaters in the present study appeared to show faster reaction times, overall, compared to nonrestrained eaters [M reaction times = 695.55 (SD = 93.61) vs. 717.64 (SD = 63.58) ms for the restrained vs. nonrestrained eaters, respectively] (see also Table III). Such findings have previously been interpreted as reflecting heightened arousal levels among restrained eaters (Herman, Polivy, Pliner, Threlkeld, & Munic, 1978). Although a t-test comparing the overall mean color-naming speeds of the restrained versus nonrestrained eaters in the present study indicated that this restraint group trend was not statistically significant [t(26) = 0.73, n.s.], overall differences in color naming between the two restraint groups were controlled for by the use of "interference indices" for forbidden and nonforbidden food cues, as the dependent measures. These two indices were calculated for each subject by subtracting the mean color-naming latency for the appropriate animal control set (forbidden or nonforbidden controls) from the mean latency for the forbidden and nonforbidden food sets, respectively. These indices reflect the relative degree of selective processing (interference in color naming) caused by the presence of forbidden or nonforbidden food cues; higher positive scores on these interference indices indicate relatively greater degrees of selective processing of forbid-


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Table II. Mean Forbiddenness Ratings of Food Words as a Function of Food Type (Forbidden vs. Nonforbidden) and Group (Nonrestrained Eaters vs. Restrained Eaters)a Group Nonrestrained eaters (N = 14) Food type Forbidden foods Nonforbidden Foods All Foods

Mean

3.86 1.79 2.82

SD

Restrained eaters (N = 14) Mean

d

(2.18) (0.58) (1.25)c

6.33 2.02 4.18

SD d

(0.60) (0.39) (0.36)c

Overall Sample (N = 28) Mean

SD

5.09 1.90 3.50

(2.01)b (0.50)b (1.14)

a

Values represent mean (and standard deviation) forbiddenness ratings made by subjects on a modified version of Knight and Boland's (1989) Food Evaluation Questionnaire; subjects rated on 9-point Likert scales the degree to which each of the Stroop food words was forbidden for them (1 = dietarily permitted; 9 = dietarily forbidden). b Main effect of food type (p < .0001). c Main effect of group (p < .001). d Simple main effect of group for forbidden foods (p < .001).

den or nonforbidden food cues (see Ben-Tovim & Walker, 1991; BenTovim et al., 1989; Cooper & Fairburn, 1993; Hope, Rapee, Heimberg, & Dombeck, 1990). This procedure controls for general color naming speed while enabling between-group comparisons of relative Stroop interference associated with the presence of food cues (McNally, Riemann, & Kim, 1990). Mean color naming speeds (in milliseconds) for forbidden and nonforbidden food words and their controls as well the associated interference indices, are indicated in Table III, as a function of group (restrained eaters vs. nonrestrained eaters). Food interference index scores were analyzed in a 2 x 2 x 2 repeatedmeasures ANOVA. Group (restrained or nonrestrained eaters) was a between-subjects variable; trial block (first block or second block) and food type (forbidden or nonforbidden) were within subjects variables. A significant main effect of group was found, F(1,26) = 6.50, p < .05. Restrained eaters demonstrated greater interference in color naming of both types of food words (forbidden and nonforbidden) than did nonrestrained eaters (see Table III). The positive mean interference index obtained by the restrained eaters indicates that restrained subjects took longer to color name food words than animal control words, while the negative mean interference index obtained by nonrestrained eaters indicates that they took longer to color name animal control words than food words (see Table III). No significant effects involving the trial block or food type factors were revealed.

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Table III. Mean Color-Naming Speeds (in Milliseconds) for Forbidden Foods, Nonforbidden Foods, and Control Words, and Color-Naming Interference Indices (Collapsed Across Trial Block) as a Function of Group (Nonrestrained Eaters vs. Restrained Eaters) Group Nonrestrained eaters (N = 14)

Restrained eaters (N = 14)

Mean

SD

Mean

SD

Forbidden foods Forbidden food control words Forbidden food interference index

711.71 717.39 -5.68

(64.57) (66.25) (33.95)

706.61 689.14 17.46

(100.39) (90.89) (33.84)

Nonforbidden foods Nonforbidden food control words Nonforbidden food interference index

716.75 724.71 -7.96

(62.44) (72.43) (36.75)

699.61 686.82 12.79

(96.15) (93.54) (20.23)

-6.82

(24.80)a

15.12

(20.56)a

Overall food interference index a

Main effect of group (p < .05).

DISCUSSION The purpose of the present study was to examine the relationship between dietary restraint and the processing of forbidden and nonforbidden food words using a modified Stroop task. Previous research has suggested that attempted avoidance of a desired substance leads to an increased preoccupation with the substance (Gross et al., 1993). Since restrained eaters attempt to selectively avoid forbidden foods in their weight control efforts, it was expected that they would be more preoccupied with, and therefore show greater Stroop interference for, forbidden food words relative to nonforbidden food words. It was also hypothesized that restrained eaters would display more Stroop interference than nonrestrained eaters for both types of food words, since restrained eaters are more conscious of the quantities and types of all foods that they eat. The hypothesis that restrained eaters would show greater interference when color naming forbidden food words than when color naming nonforbidden food words was not supported. However, restrained eaters did take significantly longer than nonrestrained eaters to color name all food words relative to control words. This latter finding is consistent with previous work (e.g., Green & Rogers, 1993; Perpina et al., 1993; Stewart & Samoluk, 1997) demonstrating that selective processing of food words is not limited to women with diagnosed eating disorders, but is also found in highly restrained individuals from the nonclinical population.


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It is possible that restrained eaters demonstrated increased interference for both forbidden and nonforbidden food words because they are equally preoccupied with both types of foods. If dietary restraint does in fact lead to nutritional deprivation (see Polivy & Herman, 1985), restrained eaters' increased Stroop interference for both forbidden and nonforbidden foods relative to nonrestrained eaters might represent distraction by the nutritional value of food cues, since both types of foods could provide some of the needed calories (see Stewart & Samoluk, 1995, 1997, for discussions of the contributions of caloric value in producing Stroop interference among restrained eaters). Riemann and McNally (1995) have recently suggested a "current concerns hypothesis" to explain Stroop interference effects. These authors found that subjects with no diagnosed psychiatric disorder showed increased latencies on the Stroop for words which were highly related to both positive and negative personal concerns compared to neutral words or words only weakly related to personal concerns. Thus, restrained eaters in the present study may have shown more interference for all food words than nonrestrained eaters because food, in general, is an area of higher current concern for restrained eaters. The current concern hypothesis (Reimann & McNally, 1995) would predict that restrained eaters would also show Stroop interference for words related to other areas of strong personal concern which are unrelated to the food domain. Although the present study did not address this possibility, previous research suggests that Stroop interference shown by restrained eaters and women with eating disorders is not limited to the food domain. Body image is another area of high current concern for women with eating disorders and those high in dietary restraint. Restrained eaters and women with eating disorders have also been shown to display increased Stroop interference for body shape words (e.g., Ben-Tovim et al., 1989; Green & Rogers, 1993; Mahamedi & Heatherton, 1993; Perpina et al., 1993). An alternative to the interpretation that restrained eaters are equally preoccupied with forbidden and nonforbidden foods, is that the modified Stroop task is simply not sensitive to relative differences in preoccupation with forbidden and nonforbidden foods among restrained eaters. This potential insensitivity may be due to the stage of information processing at which the distinction between these two food types is made. It is possible that the classification of food cues as personally relevant may occur at a relatively early stage in information processing (i.e., a stage tapped by the Stroop; see reviews by MacLeod, 1991; McNally, 1995), whereas further classification of food words as forbidden or nonforbidden may occur at a later stage of processing (i.e., not tapped by the Stroop). These speculations could be investigated in future research through the use of alternative cog-

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nitive paradigms (for reviews see McNally, 1995; Williams, Watts, MacLeod, & Mathews, 1988). For example, memory paradigms sensitive to biases in later stages of information processing could be used to determine whether selective elaboration of forbidden food cues by restrained eaters leads to greater recall/recognition of forbidden versus nonforbidden food words among restrained eaters relative to nonrestrained eaters. Several limitations to the present study should be noted. Since subjects with clinical eating disorders were not excluded from our "nonclinical" sample, the increased interference for food words shown by restrained eaters may have been due to the inclusion of many women with clinical eating disorders in the restrained eaters group. This possibility is unlikely since rates of bulimia nervosa in young adult Caucasian women have been estimated at 2% to 3% (Fairburn & Beglin, 1990). However, future research may wish to use structured interviews to exclude those with eating disorders from samples of nonclinical subjects high in dietary restraint. In addition, the use of animal words as control cues may have minimized the degree to which restrained eaters showed interference for food words, due to the animal control words' potential associations with food. Although care was taken to choose animal words that did not immediately suggest food (see Table I), future research should consider using categorized control words that are less likely to be associated with food. Finally, the assumption that restrained subjects were indeed attempting to avoid the foods used in the Stroop (particularly the "forbidden foods") to a greater extent than nonrestrained subjects was supported by subjects' retrospective reports on a modified version of Knight and Boland's (1989) Food Evaluation Questionnaire. However, retrospective reports of behavior can be subject to memory errors. Thus, future research may wish to assess the validity of this retrospective questionnaire as a measure of attempted avoidance of particular foods (e.g., by comparing scores on this measure to prospective self-monitoring records of subjects' actual attempts to avoid particular foods in their daily lives). In summary, dietary restraint was associated with the selective processing of both forbidden and nonforbidden food words on the Stroop. Thus, restrained eaters may be more preoccupied with both types of foods than non-restrained eaters, due to the association of food words with restrained eaters' current concerns. Alternatively, we have speculated that the Stroop may tap differences in the personal relevance of food cues between restrained eaters and nonrestrained eaters occurring relatively early in the information processing chain, prior to restrained eaters' later classification of food words as bad vs. good (forbidden versus nonforbidden). While more research is required to determine the precise mechanisms underlying selective processing of all food cues in highly restrained eaters, our findings


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are consistent with the results of self-report studies suggesting that dieting causes increased preoccupation with food (Franklin et al., 1966; Warren & Cooper, 1988). Further, our findings with the more objective Stroop paradigm may overcome many of the limitations inherent in self-report assessment of food preoccupations in this population.

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