A narrow notch or opening, such as a keyway in machinery or a slit for coins in a vending machine. He dropped a coin into the slot and dialled the number.

A small slit or opening in the side of an aircraft, car, truck, etc., used for airflow or to connect with other parts such as aileron or flap.

Several experimental studies are often cited for providing evidence that near misses on slot machines have a putative conditional reinforcing function, encouraging gambling persistence. For example, Strickland and Grote found that participants who saw more winning symbols on earlier presented reels (i.e., more near misses than far misses) opted to continue playing more frequently than did participants who saw fewer such symbols on earlier presented reels.

One potential limitation of these experiments is that they relied on extinction to evaluate the function of a putative conditional reinforcer. Although extinction reliably eliminates stimulus-reward associations, it is unclear whether or not it can also remove the association between near-miss density and gambling persistence. A second possible limitation is that the stimuli used were comparatively simplistic. While conventional gambling stimuli incorporate a wide range of varied shapes, patterns, and outcomes, the present studies relied on simple, neutral shapes, patterns, and outcomes in order to limit pre-existing biases.

In addition, research shows that bringing casinos with slots to cities without working to ameliorate their harms will usually lead to an increase in the number of people with gambling problems. This is true even in states that have legalized gambling, such as Massachusetts. This is illustrated by the case of Scott Stevens, who embezzled from his employer and then committed suicide after losing a lot of money playing slots.