Ivory Towers

Lunch has been attracting increased interest in academic circles recently. How do people decide what to eat, and do they fall asleep after eating it?

In their paper "Hedonic Responses, Variety-seeking Tendency and Expressed Variety in Sandwich Choices" (Appetite, April 1995, 139-152) Liisa Lahteenmaki and Hans van Trijp discuss the relationships between individuals' expressed preferences in sandwich-filling, their need for variety, and the sandwiches they eat at a free lunch.

The 26 students from the University of Helsinki who participated in the experiment were told that the study was conducted to evaluate sandwich combinations and questionnaires. Instead, researchers monitored their sandwich consumption, correlating it with their responses.

There were eight types of sandwich on offer. All contained margarine, lettuce and cucumber, but the primary ingredient could be any of sausage, liver wurst, edam-type cheese, boiled egg, tuna with mayonnaise, brie, vegetable salad in mayonnaise or pickled cucumber in mustard and vinegar. Each sandwich was cut into quarters.

Subjects were first asked to taste each type of sandwich (with the opportunity to cleanse their palates with water between bites) and assess how much they liked each filling. After the assessments, they were free to order as many of each type of sandwich as they wanted for lunch (with tea or coffee as required). They also filled in a questionnaire designed to measure a respondent's tendency to seek variety in food choice.

There was considerable difference in the number of sandwich quarters eaten by the subjects. Over the six sessions of the experiment, one ate as few as 11 in total, while another ate 94. (The mean was 31.) But the results showed a strong correlation between the type of filling chosen and an individual's expressed preferences. As the researchers put it: "Liking was identified as a major determinant of food-choice behaviour in this experiment". Variety-seeking had little to do with it.

The conclusions are clear: people eat more sandwiches with fillings they like, and if a Finn is coming for lunch, you would do better to prepare sausage, vegetable salad, boiled eggs and liver wurst sandwiches than tuna, brie, edam or pickled cucumber.

And will your guest fall asleep after lunch? The answer comes in a paper "Postprandial Sleep in Healthy Men" (Sleep, Vol 18, 1995, 229-231) by Gary Zammit, Alexander Kolevzon, Margaret Fauci, Richard Shindledecker and Sigurd Ackerman. They studied 21 men some of whom were given lunch and some not.

They then remained seated in recliner chairs for another three hours while the experiments monitored them to see if they fell asleep.

"The results of this study indicate that lunchtime food intake may not promote the initiation of sleep, but that it may increase the duration of the sleep episodes that occur during the postprandial period." Non- eaters slept an average of 30 minutes; eaters slept 93 minutes. Combined with the previous result, that works out at an average of 12.2 minutes per quarter sandwich.