A notch or other similar opening in the tips of certain birds’ primaries that during flight helps to maintain airflow over the wings. Also known as a slot, wing gap, or notch.

A gambling machine where a player drops coins or tokens into a slot to activate one or more rotating reels marked into horizontal segments by varying symbols. In the United States, a slot machine traditionally pays off two to all the coins in the machine, depending on how and where the symbols line up when the reels come to rest. Slot machines were invented in the 1880s and became popular in saloons and other establishments that allowed gambling. By the ’20s, their popularity had grown to the point that they were a significant source of income for many casinos and other establishments. The popularity of slot machines increased as a result of their ease of operation and the ability to accept large denominations of currency. By the ’30s, however, widespread fraud and illegal operations led to increasing state-level regulation of gambling machines.

Dixon et al. (2019) reported that a measure of dark flow and another measurement of reward reactivity both correlate with positive affect during slots play. We extract the PRP and force measures from their data and use them in a multivariable regression framework to show that both factors account for unique variance in positive affect during slots play. Importantly, these measures do not correlate with problem gambling or depression scores, indicating that they are not influenced by negative aspects of the gaming context.