The idea that an intervention that is new and exciting can improve motivation in the short term is not new(1) and it is believed to play an important part in testing interventions in an educational setting.
Novelty effects can also be seen as part of the Hawthorne effect. Almost all interventions introduced at the Hawthorne works between 1922 and 1934 to improve productivity worked for while only for productivity to slump back to its previous level. Perhaps the most interesting of these interventions was changes to the lighting of the factory. The improvement in productivity has been attributed to both novelty effects and the fact that performance was being measured. In fact, the Hawthorne effect may not have been observed at the Hawthorne works because most changes were made on a Monday when productivity was, in any case, greater after the weekend break. However, there is evidence from trials that it can play an important role in determining outcomes(2).
This brings me back to my exercise books. A new book with a shiny cover and fresh clean paper improved motivation and for a while at least I was able to improve my writing. Proponents of coloured overlays to treat visual stress have presented handwriting samples as evidence that their treatment works. The example below comes from Bob Hext's webinar 'Visual Stress What Everyone Should Know' prepared for the BDA. It shows changes in handwriting produced by switching to a yellow tint. Although the small improvements may be attributable to the colour used, a more plausible explanation is that they were due to the novelty effect.
Evidence of novelty effects in visual stress treatment trials
There is plenty of evidence of novelty effects in treatment trials of visual stress in dyslexia.
For example, take the key trial by Arnold Wilkins and colleagues published in 1994- A double masked placebo controlled trial of precision spectral filters in children who use overlays (3) (follow the link to see my previous post on this paper). Subjects were randomised to receive their chosen tint first or a placebo tint first. The trial was hampered by such a high rate of drop out that the results are almost meaningless. However, by far the most significant result was that 31 subjects preferred the first lens they tried and 17 the second and four did not know. Assuming equipoise was maintained and equal numbers used the chosen lens and placebo lens first this is very suggestive of novelty effects. The novelty of tinted lenses had worn off by the time they came to try the second set of lenses. This is likely to be an important confounder in the interpretation of the symptom scores. If more subjects who used the chosen lens first then it would not be surprising if results seemed to be slightly better.
Another study this time of ChromaGen contact lenses also provides intriguing evidence 'Application of ChromaGen haploscopic lenses to patients with dyslexia: a double-masked, placebo-controlled trial' (4)in fact this trial probably wasn't double masked but that's for another post. What intrigued me was that subjects who received experimental lenses before placebo showed a bigger improvement in reading rate than those who received them after the placebo lenses. If the result was purely due to tint who not expect the order of testing to make any difference.
Another 'field study' of Irlen overlays showed that in those children who used overlays for 6 months improvements in reading were only noted for the first 3 month period(5). Although the authors attributed this 'plateauing off' as subjects reaching the grade level a more plausible explanation is the novelty effect. The intervention was no longer new and interesting and it lost its motivational effect.
The high rates of attrition observed in many trials suggests novelty effects. Once the newness and excitement of the intervention had worn off the use of overlays and lenses declines sharply. For example the study published by Jeanes et al showed that although 54% of secondary school children initially chose an overlay by 3 months only 35% of the sample were still using and overlay and wished to continue and by ten months this figure had fallen to 5.1%(6).
Conclusion
Novelty effects are an important confounder in trials of educational interventions. The proponents of colour to treat visual stress in poor readers have not given sufficient thought to this problem.
1) Love A, Kavazis AN, Morse A, Mayer Jr. KC. Soccer-Specific Stadiums and Attendance in Major League Soccer: Investigating the Novelty Effect. J Appl Sport Manag Res Matters Vol 5 No 2 2013 [Internet]. 2013; Available from: http://js.sagamorepub.com/jasm/article/view/3294
2) McCarney R, Warner J, Iliffe S, van Haselen R, Griffin M, Fisher P. The Hawthorne Effect: a randomised, controlled trial. BMC Med Res Methodol. 2007;7(1):30.
3) Wilkins AJ, Evans BJ, Brown JA, Busby AE, Wingfield AE, Jeanes RJ, et al. Double-masked placebo-controlled trial of precision spectral filters in children who use coloured overlays. Ophthalmic Physiol Opt. 1994 Oct;14(4):365–70.
4) Harris D, MacRow-Hill SJ. Application of ChromaGen haploscopic lenses to patients with dyslexia: a double-masked, placebo-controlled trial. J Am Optom Assoc. 1999 Oct;70(10):629–40.
5) Noble J, Orton M, Irlen S, Robinson G. A controlled field study of the use of coloured overlays on reading achievement. Aust J Learn Disabil. 2004 Jun;9(2):14–22.
6) Jeanes R, Busby A, Martin J, Lewis E, Stevenson N, Pointon D, et al. Prolonged use of coloured overlays for classroom reading. Br J Psychol. 1997 Nov;88(4):541–8.
