Multitasking vs. Eating

Chelsea Bear, Heidi Bender, Calvin Delamere


We tested the duration of time since subjects had eaten and its effects on their ability to multitask. Knowing eating provides people with energy needed for mental processes, we hypothesized if people have more energy stored in their bodies right after they eat, then their ability to react to secondary stimuli will be quicker while answering questions the more recently they have eaten.

To test our hypothesis, we tested the reaction times of fifteen subjects. We recorded the amount of time since each subject had eaten, and then asked them a series of questions. Concurrently, they had to react to light by pushing whichever button lit up. Each subject was asked the same five questions and we recorded the average of their five reaction times. Since eating puts more energy in the body, we predicted subjects who had eaten more recently would react faster. To account for differences in finger speed, we asked each subject to begin each question with their finger in the same spot.

Our results indicated there is no correlation between the time since the subjects had eaten and their reaction times. We ran a linear regression and got an R² value of 0.14. This low R² value shows our line did not fit the data well, implying our data was scattered and inconsistent. The slope of our regression line was almost 0, showing as time since the subjects ate increased, there was no increase or decrease in reaction time. Our nearly flat slope and our p-value of 0.166 (greater than 0.05) tells us the time since the subjects last ate does not have a significant effect on their reaction times.

Our results are inconsistent with predictions based on our hypothesis. We had numerous potential problems, like our sample size being too small. Many subjects had eaten their last meal at about the same time, which limited the size of our data range. Additionally, the lab room was chaotic and it was unknown how much energy subjects devoted to answering questions versus reacting to light. If we did the experiment again, we would have subjects do two measurable tasks rather than one measurable and one immeasurable task. Also, we would test the same subjects at various times since they had last eaten. This would tell us whether variation was based on the people themselves or how long ago they had eaten.

The results of Kretsch et al. 1996 in the International Journal of Obesity reported women placed on a low-calorie diet over a long range of time had decreased reaction time. However, their sustained attention, motor performance, and immediate memory were not affected. This finding suggests the amount of food, rather than time since a person ate, affects reaction time. From our results and those of similar experiments, we propose as long as the body has sufficient energy stored, people can reach the same cognitive level as if they had just eaten. This suggests the time since a person has last eaten does not affect reaction time.