Origins of intrusions in children's dietary recalls: data from a validation study concerning retention interval and information from school food-service production records.

OBJECTIVE: To use data from a published validation study concerning retention interval and school food-service production records to examine intrusions (uneaten items reported eaten) in the school-meal parts of 24 h recalls.
DESIGN: For that study, children were observed eating two school meals (breakfast, lunch) and interviewed under one of six conditions from two target periods (previous day (PDTP), prior 24 h (24TP)) crossed with three interview times (morning, afternoon (AIT), evening). For the present article, a catalogue was constructed of foods available for that study's school meals. The study's intrusions were classified as stretches (on children's meal trays but uneaten), internal confabulations (in children's school food-service environments for that meal but not on children's trays) or external confabulations (not in children's school food-service environments for that meal). Occurrence, types and amounts of intrusions were investigated. SETTING/
SUBJECTS: Six schools; sixty fourth-grade children (ten per condition).
RESULTS: For breakfast, for the 24TP v. PDTP, reported items were less likely to be intrusions, internal confabulations and external confabulations; and intrusions were more likely to be stretches. For lunch, for the 24TP-AIT condition v. the other five conditions, reported items were less likely to be intrusions and external confabulations. Mean amounts reported eaten were smaller for stretches than for internal confabulations or external confabulations at breakfast, and for stretches than for internal confabulations at lunch.
CONCLUSIONS: Accuracy was better for the 24TP (with fewer intrusions of which proportionally more were stretches which had smaller amounts reported eaten) than for the PDTP. Studies with 24 h recalls should minimize retention interval to improve accuracy.