Does the memory of a large meal affect future hungriness? According to researchers from the University of Bristol, led by Jeffrey Brunstrom, yes, it can.
What I love most about this study is the self-filling soup bowl used by the researchers. 100 participants were shown bowls containing either 300 or 500 ml of soup. They proceeded to eat the soup. Unbeknownst to the diners, the bowls had a secret filling/emptying system that covertly changed the amount of soup in the bowls. Thus, the people who saw 300 ml in their bowls were actually eating either 300 or 500 ml of soup. In the same way, the people who were presented with 500 ml of soup actually ate either 300 or 500 ml. There were 25 people in each of these four groups.
You can see a diagram of the soup-filling apparatus below. Volunteers were instructed to stop eating when the soup reached a certain line in the bowl to ensure that they didn’t discover the filling apparatus at the bottom (the total amount of soup was adjusted to account for this).
Only six people out of hundred noticed that the volume of soup in their bowls was being manipulated. Those people were replaced with another six volunteers.
The subjects had been asked to abstain from eating for at least three hours before the test. After eating their soup, they were sent home with a buzzer to remind them to rate their level of hunger every hour for the next three hours. People who thought they had eaten 500 ml of soup but really had only consumed 300 ml reported more satiety than people who consumed 500 ml of soup but thought they had eaten 300 ml. In other words, the perception of having eaten a large meal had a great effect than the actual amount ingested.
Brunstrom JM, Burn JF, Sell NR, Collingwood JM, Rogers PJ, Wilkinson LL, Hinton EC, Maynard OM, & Ferriday D (2012). Episodic memory and appetite regulation in humans. PloS one, 7 (12) PMID: 23227200.