People were given phones with nothing but numbers on them and then asked to type in a series of digits, ostensibly as part of an ergonomics study. Instead, the authors were tracking the words that those keys might spell were they being used to punch out a quick text. Unconsciously, it seems the participants were as well. Keying in 5683, which could potentially spell "love" was viewed as a more positive experience than 75463 for "slime."