A slot is a thin opening or groove in something, often used for receiving or admitting something, such as a coin. There are several types of slots, including the ones found in video games and casinos. The term can also refer to a position or time period, such as the slot a program occupies on a broadcasting schedule.

In the past, slot machines were mechanical devices that spun reels with symbols. Modern machines are controlled by electronic technology, using random number generators to determine the positions of symbols on each reel. The odds of winning are determined by the symbols that line up on a payline. In some slots, the symbols can appear on multiple reels and trigger different bonus rounds.

While the rewards triggered by a big win might be enjoyable, problem gamblers also experience dark flow when playing slots. The intermittent reinforcement of attention from the visuals and sounds of the machine may allow them to engage in a state of mind that feels more like flow than usual, which might explain why they enjoy slots so much. Dixon et al. (2019) found that mindfulness problems outside gambling are associated with increased endorsement of dark flow during slots play. However, the results of their study only indicate a correlation between mindfulness and enjoyment and do not establish causality. Future research should focus on determining whether the mechanisms underlying dark flow in slots are distinct from those involved in other forms of enjoyment.