Engagement or manipulation? Sight and sound in online slots

Engagement or manipulation? Sight and sound in online slots - Banner
Paul Clare
by Paul Clare Last updated:

The slots market is a competitive one, and developers know they need to work every angle to get an edge. This means honing and refining each and every element of a game with the singular goal of keeping the player engaged.

To accomplish this, slots employ a variety of visual and auditory effects. Slots development this way has happened alongside advancements in psychology, with developers applying the science of the mind to find more ways to engage us.

In this article we consider the key sight and sound elements that influence slot design and play:

  • Visuals, including technology, iconography, colour
  • Sounds, including soundscapes and positive reinforcement
  • Themes
  • The balance between engagement and manipulation


There are many ways in which visuals can be harnessed for the development of the best online slots, with tech, icons and colours all playing an important role.


These days, the majority of slots are delivered to players via high-definition screens with the sort of capability that early physical slot machine makers can only have dreamt of. 

Visual technologies have facilitated some incredible advancements in slot development, with machines no longer being confined to a few reels and static imagery.

Animations are more engaging than still images, and many modern slots fans choose to play games with more elaborate visuals. One might assume this is preferable to a simple background with a block of reels imposed onto it. However, some developers continue to work with more basic methods. This suggests there’s still a market for old-school slots enthusiasts who aren’t as receptive to change.


Symbolism is at the heart of slot design, whether it’s classical fruit symbols, lucky 7s or rainbows leading to pots of gold. New online slots, however, take this to the next level. Choice imagery can be used to tap into a range of player emotions, evoking powerful feelings and enhancing gameplay.

For example, traditional symbols like bars, 7s, bells and fruit can trigger nostalgia – particularly amongst those who first encountered slots in brick-and-mortar casinos, arcades and pubs. Whisking players back in time like this can be subconsciously comforting, keeping them in something of a 'psychologically safe space' whilst they spin.

Similarly, imagery can suggest wealth, appealing to the player’s desire for big wins. Dollar symbols and gold coins are prime examples of this. Focusing players on the potential wins is one of the most effective ways to keep them spinning.


Much psychological research has been done on the powers of specific colours. A lot of this has been applied to slot design, using pre-existing associations in the mind of the player to boost gameplay. 

Building a carefully designed colour palette is a powerful way to bolster a game’s theme and give it a unique, memorable identity. Brightness too is stimulating, and encourages player engagement.

Specific colours are associated with various emotions for most people. For example, greens are used in slot design to suggest luck and nature, whereas gold is, of course, associated with wealth and luxury.


Some psychological research reveals that intelligent sound design in slot development is a highly effective method of enhancing a game.


Slot games tend to have an ambient soundbed to reinforce the theme. These can be carefully chosen to achieve a variety of things.

For instance, horror games may employ an unsettling soundtrack to chill the player and build tension, complemented by the sort of sound effects we know from horror films. Or they might aim to create a tranquil, calming soundscape, as is the case with many fishing-themed titles. 

Some games even give players a playlist to choose from, enabling them to tailor the experience to their own preferences. If carefully chosen, a soundtrack can be an excellent way to keep players engaged.

Positive reinforcement

Sounds are often used to create mental associations between playing slots and dopamine releases, encouraging us to keep going. 

Many games share similar audio effects, such as the sound of coins showering down, or bells announcing wins. The psychological effects are even shared across different slots.

Various game mechanics including changing the stake size, spinning the reels, holding reels and hitting bonuses tend to have specific sounds associated with them. Highlighting things like this makes for a richer player experience and greater player retention rates.


Different themes appeal to different players, with most slots fans having their own personal preferences. Both visuals and sound are a huge part of creating the theme and executing it effectively. 

Bright, light-hearted slots with quirky designs, such as some of those made by Hacksaw Gaming, use sound effects to keep players wondering what may be around the corner. Games based on existing IPs will generally use sounds and visuals already associated with the franchise, immersing the player in a world they already appreciate.

It's safe to assume from an operator perspective that certain themes are more successful than others – which explains why we see the same themes crop up again and again. These are then copied by secondary developers looking to emulate the success of the first – fishing-themed games being a fairly recent, and obvious, example.

A fine line

Slot designers and developers have a responsibility to create a high-quality product which engages players, keeping them entertained and spinning. However, it could be argued that going too far down this road might constitute coercion or manipulation.

It’s the UKGC’s responsibility to monitor and regulate this area, and they’ve already made some interventions regarding how sight and sound are used in slot design. 

For instance, in the past certain games would play a sound effect suggesting a win, such as the chiming of a bell, even when the win was lower than the stake. This played down the negative impact of the loss, encouraging the player to spin again.

This disguising losses as wins is no longer allowed. With so much influence built into the sights and sounds of a slot machine, and ethical aspects to consider, it’s reassuring to know that the UKGC has its finger on this particular pulse.

There's also a balance to strike in terms of avoiding the overuse of effects – which some developers utilise more effectively than others. Just as great sound effects and visuals can enhance a game, poorly chosen ones can detract from it. 

One example of divisive sound design is NoLimit’s Land of the Free, which is set in a US trailer park and features a soundtrack of stars and stripes-themed heavy metal music accompanied by some fairly offensive lyrics. Generally speaking, developers such as NoLimit, Relax Gaming and Push Gaming are appreciated for their progressive sound and visual effects.


Ultimately, keeping players engaged comes about by rewarding them, and this involves much more than cash prizes. Alongside our understanding of the human brain, the sound and visual design of slot games will continue to evolve.

The mechanisms we have discussed are used by developers for a range of effects. This could be to create a calm, safe virtual space, reinforce a horror theme with eerie tones and spooky sights or take you on a trip through ancient Egypt or the Wild West.

Our favourite slots wouldn’t be what they are without their visual and auditory effects. However, it remains important that the UKGC monitors the extent to which such psychological phenomena are employed.