Cherries, bells, bars and sevens are among the most recognisable images associated with slot machines. Their familiarity can make them seem inevitable, but the visual vocabulary of the slot developed gradually, alongside changes in mechanics, manufacturing and display technology.
Some symbols originated in the earliest mechanical machines. Others appeared later and became established through repeated use. What is particularly striking is that many of them survived the transition from physical reels to digital screens.
The technology changed substantially; the visual language changed much more slowly.
The bell belongs to the earliest history of the machine
The bell is closely connected with the development of the modern slot machine.
Encyclopaedia Britannica’s history of the slot machine traces a key stage in its development to Charles Fey’s Liberty Bell machine in San Francisco at the end of the 19th century. The machine used three reels carrying a limited group of symbols, including horseshoes, playing-card suits and bells.
That restricted vocabulary reflected the physical design of the machine. Symbols had to fit onto mechanical reels, remain visually distinct and be recognisable through a relatively small display window.
The bell therefore began as part of a practical graphical system rather than simply as decoration. Through repeated use and association with early machines, it eventually became one of the visual references most strongly linked to the category.
Fruit arrived through a different route
Fruit symbols have a different history.
During the early 20th century, some machines were designed around non-cash rewards such as chewing gum. Fruit imagery became associated with flavours and products, helping cherries, lemons, oranges and similar graphics become established on reels.
Evidence of how durable that convention became can be seen in the Science Museum Group’s collection of gambling machines, which includes a mid-20th-century Merkur machine using the kind of fruit-based imagery that had by then become firmly associated with the format.
By that point, the symbols no longer needed to communicate a literal flavour. Their repeated appearance had given them a second function: they identified the machine visually.
This is an important shift in graphic design. An image introduced for one reason can remain after its original context has faded because audiences have learned to associate it with something else.
Numbers offered a compact visual language
Numbers followed a simpler logic.
They are economical graphic elements: easy to reproduce, easy to distinguish and capable of fitting into a small area. These qualities made them useful on physical reels, particularly when manufacturers needed symbols that could be recognised quickly.
Some numbers then developed stronger cultural associations than others. Seven is the obvious example. It has appeared repeatedly in slot-machine graphics and has become visually associated with ideas of luck across a much wider cultural context.
That does not give seven a universal technical significance across slot machines. Its importance is graphical and cultural rather than mechanical.
This distinction matters. A symbol can become familiar without having the same function, value or probability in every product where it appears.
Physical constraints created lasting conventions
Mechanical reels imposed strict limits on visual design.
There was only so much room available, and each symbol needed to remain distinguishable as the reel moved and stopped. Simple forms therefore had an advantage over detailed illustrations.
Bells, fruit, numbers and playing-card symbols all work well under those constraints. Their silhouettes are easy to differentiate, and each can be simplified without becoming unrecognisable.
Once those conventions had been established, later technologies inherited a ready-made graphical vocabulary.
Electronic displays could have abandoned them completely. Digital screens certainly could. Instead, designers frequently retained at least some of the imagery associated with earlier machines.
Digital slots no longer need the old symbols
The transition to online slots removed many of the physical limitations that originally shaped slot-machine graphics.
A digital interface is not restricted to symbols printed on a mechanical reel. Software can display detailed illustrations, animation, typography and visual effects that would have been impossible on early machines.
That makes the continued presence of fruit, bells or sevens particularly interesting. In a digital environment, their use is no longer dictated by mechanics.
They have become design references.
The same pattern can be found throughout digital interfaces. A familiar visual object can remain useful long after the technology that originally required it has disappeared. The graphic survives because its meaning has already been learned.
Symbols can become more abstract over time
As visual conventions become familiar, they can also become increasingly stylised.
A bell does not need to be rendered realistically to be identified as a bell. A cherry can be reduced to a pair of circles and a stem. A seven can be stretched, outlined or combined with other graphic elements while remaining immediately legible.
This gives designers considerable freedom.
The symbol can change stylistically while maintaining its basic identity. In that sense, the history of slot imagery is not simply one of preservation. It is also one of abstraction.
Mechanical limitations established the initial forms; later graphic design allowed those forms to be simplified, exaggerated or reinterpreted.
The visual language outlived the machinery
The persistence of classic slot symbols illustrates a broader principle in design history.
Technology does not always erase the visual conventions of the technology it replaces.
The mechanical reels, levers and internal components of early machines belonged to a very different technical environment from contemporary digital interfaces. Yet some of the images associated with those machines remain recognisable more than a century later.
Fruit, bells and numbers survived because they moved from being individual graphics on a physical reel to becoming part of a shared visual vocabulary.
The machinery changed. The symbols acquired a life of their own.