title: Underestimating calorie content when healthy foods are present: an averaging effect or a reference-dependent anchoring effect?
abstract: OBJECTIVE
  Previous studies have shown that estimations of the calorie content of an unhealthy main meal food tend to be lower when the food is shown alongside a healthy item (e.g. fruit or vegetables) than when shown alone. This effect has been called the negative calorie illusion and has been attributed to averaging the unhealthy (vice) and healthy (virtue) foods leading to increased perceived healthiness and reduced calorie estimates. The current study aimed to replicate and extend these findings to test the hypothesized mediating effect of ratings of healthiness of foods on calorie estimates.
  
  
  METHODS
  In three online studies, participants were invited to make calorie estimates of combinations of foods. Healthiness ratings of the food were also assessed.
  
  
  RESULTS
  The first two studies failed to replicate the negative calorie illusion. In a final study, the use of a reference food, closely following a procedure from a previously published study, did elicit a negative calorie illusion. No evidence was found for a mediating role of healthiness estimates.
  
  
  CONCLUSIONS
  The negative calorie illusion appears to be a function of the contrast between a food being judged and a reference, supporting the hypothesis that the negative calorie illusion arises from the use of a reference-dependent anchoring and adjustment heuristic and not from an 'averaging' effect, as initially proposed. This finding is consistent with existing data on sequential calorie estimates, and highlights a significant impact of the order in which foods are viewed on how foods are evaluated.
authors: Behaviour and Health Research Unit, Department for Public Health and Primary Care, University of Cambridge, Cambridge, United Kingdom. Sef26@cam.ac.uk
authors: Suzanna E
authors: SE
authors: Forwood
authors: Amy
authors: A
authors: Ahern
authors: Gareth J
authors: GJ
authors: Hollands
authors: Paul C
authors: PC
authors: Fletcher
authors: Theresa M
authors: TM
authors: Marteau
mesh_terms: D000328:Adult; D002149:Energy Intake; D005260:Female; D058870:Food, Organic; D006801:Humans; D007088:Illusions / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D012015:Reference Standards; D055815:Young Adult
references: J Pers Soc Psychol. 2011 Mar;100(3):407-25
references: 21280961
references: Nature. 2012 Mar 28;483(7391):531-3
references: 22460880
references: PLoS One. 2012;7(3):e33423
references: 22432019
references: Health Psychol. 1996 Nov;15(6):438-47
references: 8973924
references: Perspect Psychol Sci. 2012 Nov;7(6):537-42
references: 26168110
references: Int J Obes Relat Metab Disord. 2000 Dec;24(12):1715-25
references: 11126230
references: Science. 1974 Sep 27;185(4157):1124-31
references: 17835457
references: Perspect Psychol Sci. 2012 Nov;7(6):528-30
references: 26168108
references: PLoS One. 2012;7(1):e29081
references: 22279526
references: Science. 1981 Jan 30;211(4481):453-8
references: 7455683
references: PLoS Med. 2005 Aug;2(8):e124
references: 16060722
references: Br J Nutr. 2011 Mar;105(6):810-5
references: 21078214
references: J Pers Soc Psychol. 1996 Aug;71(2):230-44
references: 8765481