Albert F. Smith

Cognitive research enhances accuracy of food frequency questionnaire reports: results of an experimental validation study

OBJECTIVE To test whether changing a food frequency questionnaire (FFQ) on the basis of cognitive theory and testing results in greater accuracy. Accuracy was examined for 4 design issues: a) Grouping: asking about foods in a single vs multiple separate questions; b) different forms of a food: asking consumption frequency of each form of a food (eg, skim, 2%, whole milk) vs a nesting approach--asking frequency of the main food (eg, milk) and proportion of times each form was consumed; c) additions (eg, sugar to coffee): asking independent of the main food vs nested under the main foods; d) units: asking frequency and portion size vs frequency of units (eg, cups of coffee). DESIGN Participants in two randomly assigned groups completed 30 consecutive daily food reports (DFRs), followed by 1 of 2 FFQs that asked about foods consumed in the past month. One was a new, cognitively-based National Cancer Institute (NCI) Diet History Questionnaire; the other was the 1992 NCI-Block Health Habits and History Questionnaire. SUBJECTS/SETTING 623 participants, age range 25 to 70 years, from metropolitan Washington, DC. Statistical analyses performed Accuracy was assessed by comparing DFR and FFQ responses using categorical (percent agreement) and continuous (rank order correlation, discrepancy scores) agreement statistics. RESULTS Grouping: accuracy was greater using separate questions. Different forms of food: accuracy was greater using nesting. Additions: neither approach was consistently superior; accuracy of the addition report was affected by accuracy of the main food report. Units: both approaches were similarly accurate. CONCLUSIONS Accuracy of FFQ reporting can be improved by restructuring questions based on cognitive theory and testing.

The bow and sequential effects in absolute identification

The bow and sequential effects in absolute identification are investigated in this paper by following two strategies: (1) Experiments are performed in which sequential dependencies in signal presentations are manipulated, and 12) analyses are conducted (some of which are largely free of model-specific assumptions) which bear directly on the question of the origin of the sequential effects. The main result of the study is that absolute identification performance is greatly improved in a design in which each signal lies close to the preceding signal presented, even though the entire range of signals used is the same as in a random presentation design. This finding is consistent with the attention-band model of Luce, Green, and Weber (1976) and rejects hypotheses that suggest that the variability in the signal representation in absolute identification is a function solely of the range of signals being used. However, nonparametric analyses of sequential response errors show that a plausible assumption concerning the trial by-trial movement of the attention band provides an incomplete explanation of Seluential effects in absolute identification. These results are far better explained in terms of systematic shifts of category boundaries in a Thurstonian model, as suggested by Purks, Callahan, Braida, and Durlach (1980). Experiments are also performed which suggest that memory decay is not the major factor accounting for the bow effect in absolute identification.

Perceptual interference and facilitation with auditory imagery

It has been claimed both that (1) imagery selectivelyinterferes with perception (because images can be confused with similar stimuli) and that (2) imagery selectivelyfacilitates perception (because images recruit attention for similar stimuli). However, the evidence for these claims can be accounted for without postulating either image-caused confusions or attentional set. Interference could be caused by general and modality-specific capacity demands of imaging, and facilitation, by image-caused eye fixations. The experiment reported here simultaneously tested these two apparently conflicting claims about the effect of imagery on perception in a way that rules out these alternative explanations. Subjects participated in a two-alternative forced-choice auditory signal detection task in which the target signal was either the same frequency as an auditory image or a different frequency. The possible effects of confusion and attention were separated by varying the temporal relationship between the image and the observation intervals, since an image can only be confused with a simultaneous signal. We found selective facilitation (lower thresholds) for signals of the same frequency as the image relative to signals of a different frequency, implying attention recruitment; we found no selective interference, implying the absence of confusion. These results also imply that frequency information is represented in images in a form that can interact with perceptual representations.

Individual magnitude estimates for various distributions of signal intensity

Magnitude estimates of loudness were collected for several variations in the schedule of signal presentations. For wide ranges (about 50 dB centered at 65 dB), the conditions were: random selection of 21 signals equally spaced in decibels, constrained selection so that each signal was used equally often but successive signals were always close together, constrained selection in which successive signals were always far apart, and random selection from a nonuniform distribution that consisted of two groups of equally spaced signals separated by a gap of 24 dB. In addition, two other ranges, 10 and 30 dB, were run with random selection of 21 equally spaced signals. The measures examined were: mean magnitude estimate as a function of signal intensity, coefficient of variation of the ratio of successive responses as a function of signal separation, and the correlation of the logarithm of successive responses as a function of signal separation. The basic question was whether all of the different schedules of signal presentation produce data that can be viewed as selections from appropriate regions of the 50-dB random signal selection data. To a degree, this was found, but with systematic exceptions.

How children remember what they have eaten

OBJECTIVES To determine whether students could verbalize, within 1 1/2 hours, how they remembered items eaten at the school lunch; to determine whether the categories of self-reported retrieval mechanisms were similar for two interview styles, integrated and nonintegrated; and to determine the effect of the two interview style on the accuracy of reporting items eaten by comparing reports with direct observation. DESIGN Two styles of dietary intake interviews were compared with observed intake in a school lunch setting. SETTING Two elementary schools in Georgia. SUBJECTS/SAMPLES Eighty-two of 106 fourth graders from four classes volunteered; 24 (six per class) were randomly selected and assigned to an interview style. Students interviewed using a nonintegrated style verbalized how they remembered after they had reported everything eaten. Students interviewed using an integrated style verbalized how they remembered at the same time they reported eating each item. Both interview styles included free report followed by prompted report. MAIN OUTCOME MEASURES Reported retrieval mechanisms were coded into 13 categories. Five measures of performance (specific match rate, general match rate, intrusion rate, omission rate, and overall match rate) were calculated by interview style for free report and prompted report separately. STATISTICAL ANALYSES PERFORMED We analyzed the effect of interview style on the number of students reaching 100% accuracy after prompting and on accuracy of reporting condiments using Fishers exact test. RESULTS Most students could articulate how they remembered items eaten. Reported retrieval mechanism categories were comparable for both interview styles. Visual imagery, usual practice, behavior chaining, and preference were the most commonly reported retrieval mechanisms. Accuracy of free reports did not differ by interview style; however, the nonintegrated interview style produced dietary self-reports with fewer condiment omissions during free report and higher accuracy after prompting. APPLICATIONS Determining what retrieval mechanisms children commonly use for remembering items eaten may help researchers design cues to improve the accuracy of dietary self-reports. More accurate dietary self-reports could markedly affect the many types of research that use dietary assessment.

Reverse versus forward order reporting and the accuracy of fourth-graders’ recalls of school breakfast and school lunch

BACKGROUND Do children recall school breakfast and school lunch intake during 24-h recalls more accurately when prompted to report meals and snacks in reverse versus forward order? METHODS One hundred twenty-one fourth-graders stratified by race (Black, White) and gender were each observed and interviewed twice (once per order) regarding the previous days intake. Omission and intrusion rates determined accuracy for reporting items. Total inaccuracy determined accuracy for reporting items and amounts. RESULTS Results failed to indicate significant effects of interviewer, weekday, sequence (first or second recall), or race on omission rates, intrusion rates, or total inaccuracy. A significant order by gender interaction was found for omission rates, which were lower (i.e., better) for males for reverse (53%) versus forward recalls (62%), but not females (61 versus 53%) (P < 0.008). Intrusion rates were acceptable for males for 54% of reverse recalls and 40% of forward recalls (P = 0.095). Means were 57 and 32%, and 6.4 servings for omission rate, intrusion rate, and total inaccuracy for reverse recalls, and 56 and 39%, and 6.9 servings for forward recalls. CONCLUSIONS Prompting children to report in reverse versus forward order improved omission and intrusion rates for males more so than females. Regardless of reverse or forward order, children reported <50% of items observed; furthermore, >30% of items reported were not observed. Research is needed to enhance accuracy of childrens dietary recalls.

Children's Social Desirability and Dietary Reports

We investigated telephone administration of the Childrens Social Desirability (CSD) scale and our adaptation for children of the Social Desirability for Food scale (C-SDF). Each of 100 4th-graders completed 2 telephone interviews 28 days apart. CSD scores had adequate internal consistency and test-retest reliability, and a 14-item subset was identified that sufficiently measures the same construct. Our C-SDF scale performed less well in terms of internal consistency and test-retest reliability; factor analysis revealed 2 factors, 1 of which was moderately related to the CSD. The 14-item subset of the CSD scale may help researchers understand error in childrens dietary reports.

The psychological refractory period: evidence for age differences in attentional time-sharing

The authors report 2 psychological refractory period (PRP) experiments in which the stimulus onset asynchrony (SOA) between Task 1 and Task 2 was 150 ms, 250 ms, 600 ms, and 1,100 ms for both younger and older adults. H. Pashlers (1994a) response-selection bottleneck theory predicts that SOA manipulations should not affect Task 1 performance, but that reaction time (RT) for Task 2 should increase as the SOA between the 2 tasks decreases (i.e., the classical PRP effect). In Experiment 1 (Task 1 = tone discrimination, Task 2 = dot location), older adults showed a larger PRP effect than younger adults did, although Task 1 RT was affected by SOA, suggesting that participants were grouping their responses on some trials. That is, participants were holding their response for Task 1 until they had completed processing Task 2, and then they responded to both tasks almost simultaneously. However, a subset of participants (11 younger adults and 11 older adults) who showed no evidence of response grouping on Task 1 continued to show a larger PRP effect for older adults on Task 2. In Experiment 2 (Task 1 = dot location, Task 2 = simultaneous letter matching), older adults continued to show a larger PRP effect than younger adults for Task 2, and Task 1 performance was unaffected by SOA. Consequently, these experiments provide evidence that older adults (relative to younger adults) exhibit a decrement in time-sharing at the response-selection stage of processing. These results suggest that attentional time-sharing needs to be added to the list of topics examined in aging research on varieties of attention.

Fourth-Grade Children's Dietary Recall Accuracy Is Influenced by Retention Interval (Target Period and Interview Time)

BACKGROUND For a 24-hour dietary recall, two possible target periods are the prior 24 hours (24 hours immediately preceding the interview time) and previous day (midnight to midnight of the day before the interview), and three possible interview times are morning, afternoon, and evening. Target period and interview time determine the retention interval (elapsed time between to-be-reported meals and the interview), which, along with intervening meals, can influence reporting accuracy. OBJECTIVE The effects of target period and interview time on childrens accuracy for reporting school meals during 24-hour dietary recalls were investigated. DESIGN AND SUBJECTS/SETTING: During the 2004-2005, 2005-2006, and 2006-2007 school years in Columbia, SC, each of 374 randomly selected fourth-grade children (96% African American) was observed eating two consecutive school meals (breakfast and lunch) and interviewed to obtain a 24-hour dietary recall using one of six conditions defined by crossing two target periods with three interview times. Each condition had 62 or 64 children (half boys). MAIN OUTCOME MEASURES Accuracy for reporting school meals was quantified by calculating rates for omissions (food items observed eaten but unreported) and intrusions (food items reported eaten but unobserved); a measure of total inaccuracy combined errors for reporting food items and amounts. STATISTICAL ANALYSES PERFORMED For each accuracy measure, analysis of variance was conducted with target period, interview time, their interaction, sex, interviewer, and school year in the model. RESULTS There was a target-period effect and a target-period by interview-time interaction on omission rates, intrusion rates, and total inaccuracy (six P values <0.004). For prior-24-hour recalls compared to previous-day recalls, and for prior-24-hour recalls in the afternoon and evening compared to previous-day recalls in the afternoon and evening, omission rates were better by one third, intrusion rates were better by one half, and total inaccuracy was better by one third. CONCLUSIONS To enhance childrens dietary recall accuracy, target periods and interview times that minimize the retention interval should be chosen.

Interview format influences the accuracy of children's dietary recalls validated with observations

This report describes a comparison of the accuracy of childrens dietary recalls obtained using either open or meal format interviews. Fourth-graders were randomly selected, observed eating school meals (breakfast, lunch), and interviewed that evening regarding that days intake with children randomly assigned to open (n = 12) or meal (n = 11) format interviews. The weighted numbers of items observed eaten did not differ by format, but greater weighted numbers of items were reported eaten with meal format interviews than with open format interviews. Reporting performance was more accurate with open than with meal format interviews: Although the omission rates did not differ significantly between the formats, higher intrusion rates and total inaccuracy were found in meal format interviews than in open format interviews. Interview format influences childrens dietary reporting accuracy; in particular, providing meal cues elevates false reports. These analyses exemplify the importance of treating omissions and intrusions separately when examining reporting performance.