Everyday Research Methods

Is "sugar high" a thing?

 

Sugar doesn't make kids hyperactive; at least not according to a null effect study and a meta-analysis. Photo: Alamy

Here's something "everybody says":  Kids will become hyperactive if they eat too much sugar. This folk belief is as much a part of North American cultural wisdom as learning styles and the catharsis hypothesis. But this column in the New York Times explains that, like learning styles and catharsis, the idea of a "sugar high" is also a myth. 

 

The physician who wrote the column traced the modern idea of sugar causing hyperactivity to 1975. But then the author describes a randomized clinical trial on this question. Here's the description: 

An extraordinarily rigorous study settled the question in 1994. Writing in the New England Journal of Medicine, a group of scientists tested normal preschoolers and children whose parents described them as being sensitive to sugar. Neither the parents, the children nor the research staff knew which of the children were getting sugary foods and which were getting a diet sweetened with aspartame and other artificial sweeteners. Urine was tested to verify compliance with the diets. Nine different measures of cognitive and behavioral performance were assessed, with measurements taken at five-second intervals.

The original study was, indeed, ambitious. The authors provided all food to the homes of the children in the study so they could completely control what sweeteners were being used. The study took place over nine weeks in a repeated-measures design--the diets were based on sucrose (sugar) one week, aspartame another week, and saccharine during another week. The researchers measured the children's cognitive performance and mood throughout the study.

The study concluded that sugar does not affect children’s behavior or cognitive function. An editorial that accompanied the study put a fine point on that conclusion, stating “there is no evidence that sugar alone can turn a child with normal attention into a hyperactive child.” 

Questions

a) What were the independent and dependent variables in the study described here? What are the levels of the IV?

b) The IV was manipulated as within subjects, using a repeated-measures design. Describe why counterbalancing would be important here, and how you could counterbalance in this study. Which of the four big validities does counterbalancing support?

c) What questions could you ask about the other three validities for this study? 

d) This study found a null effect (no impact of sucrose on children's behavior). There were only 48 children in the diet study, and this might be considered a low number--there may not have been enough kids in the study to detect a small effect of sucrose. However, the repeated measures design means this study can make a stronger case for the conclusion that sugar doesn't affect kids' behavior. Review the information in Chapter 11 to explain why the repeated measures design helps support the conclusion. 

The author of the piece mentions this, too:

One year later, an analysis that gathered data from all published studies on the subject reached the same conclusion.

e) This sentence is describing a meta-analysis. In your own words, describe what steps they would have taken to conduct this meta-analysis.

f) Why is a meta-analysis stronger evidence for a null effect of sugar on hyperactivity? 

g) Given this information, what would you say to a relative or friend who believes that sugar causes hyperactivity in their own child? 

 

A serendipitous study of long-term memory in birds

Here's a photo of a toutouwai (North Island Robin) sporting its bands for identification. Photo: Shutterstock

We don't include many animal behavior studies in ERM blog, but here's a great one about animal memory. How long do you think wild animals can remember new skills they have learned? In this report in The Scientist, we read that the North Island Robin (known in the Maori language as toutouwai) of New Zealand can apparently remember a skill up to 22 months, without any reminders in the meantime. Here's how the study worked. 

[Originally, scientist Rachel Shaw] demonstrated that wild toutouwai living in the Zealandia Wildlife Sanctuary in Wellington, New Zealand, are capable of learning a novel task. Using a rectangular box with three compartments, each covered by a lid that swivels to the side to reveal its contents, she incrementally taught the birds how to peck the lids aside and retrieve mealworms hidden inside two of the three wells.

(By the way, the story in The Scientist includes a photo of the experimental apparatus and a video of a bird using it.)

Roughly a year later, Shaw was giving a public talk at the sanctuary about conservation and her work with birds. As she explained the memory apparatus she had used in her previous research, a toutouwai appeared.

“I haven’t given this bird this task in over a year,” she recalls telling the audience, “so let’s see how he does.” As if on cue, the bird instantly flew down to the apparatus and started opening the lids. That got her wondering: how many of the other birds could repeat the memory task and how long could they remember what they were taught?

This serendipitous event prompted Dr. Shaw to design a study to find out. Before reading on, how would you study this question? 

In the new study, Shaw and her coauthor, Annette Harvey, tested 32 of the initial 64 birds that were trained in 2015 and 2016 and banded for individual identification, 30 of which performed the memory task by spontaneously pecking the lids and opening them on their first try. None of the trained birds had seen the box between the initial training and retesting, though some of the untrained control birds had encountered the apparatus in a previous research project. The time between when the birds had first learned the lid-opening behavior and subsequent testing ranged from 10 to 22 months. By contrast, the 17 untrained birds were unable to complete the task.

The article mentions several other examples of long-term memory in animals, including pigeons, tortoises, nutcrackers, and chickadees. Read more if you are interested!

Questions

a)  This study might be considered a simple observational study but it might also be classified as a quasi-experiment. What do you think?

b) What role does the untrained comparison group play in this research? 

c)  Do you think the effect size in this study would be considered small or large? Explain your answer.

d) Chapter 6 describes important construct validity considerations for observational studies, such as reactivity, observer bias, and observer effects. Which of these might be relevant in this study on toutouwai? 

Thanks to my friend Dr. Stephen Chew for sharing this story on Twitter!