How a visual works on the reader

A visual can make part of a complex message easier to perceive, leaving more mental effort for what still needs explanation. Its effect depends on what the audience already knows, what the image makes noticeable and whether its content supports the message.

Perception and prior experience

Light entering the eye is converted into electrochemical signals that pass from the retina to the brain, where prior experience and information help turn them into meaning. ¹ Perception has physiological and psychological aspects and differs between individuals, capturing some information and discarding the rest. ¹ People recognise patterns by drawing on previously acquired knowledge and experience. ¹

In a hotel-bathroom example, an automatic hand dryer beside paper towels resembled a bin, inviting used towels to be thrown towards it even though the actual bin stood about a metre to the right. ²

Mental effort and intuitive understanding

Kahneman’s fast-and-slow framework distinguishes two categories of mental processes, rather than two anatomical parts of the brain. ³ System 1 is fast and automatic, as when answering one plus one or immediately recognising a person’s mood from their face. ⁴ System 2 is slow, deliberate and effortful, as when multiplying 27 by 135 or attending consciously to gears, pedals and mirrors while learning to drive. ^{5, 6} With experience, some tasks such as driving become more automatic. ⁶ Deliberate processing can minimise errors but demands scarce mental effort, so shortcuts are often used. ^{6, 7}

Applied to visual communication, this framework treats a complex message as a body of difficulty that a reader must work through. ⁷ Presenting part of it intuitively through an image can reduce the complexity requiring deliberate thought, without removing all of it. ^{7, 8} The design goal is to make the route to the message accessible and effortless so that the communication method adds as little difficulty as possible to an already complex subject. ^{9, 10}

Visual analogies can build on a mental model the audience already holds, substituting new elements within a familiar framework. ¹¹ Common metaphors such as a seesaw or pyramid are recommended because the audience already has a framework for interpreting them. ^{12, 11}

Attention and relevance

Adding irrelevant visuals, sounds or words distracts an audience and impairs learning; visual elements enhance learning only when they are relevant. ¹³ Projected images likewise need to follow basic principles of human perception to enhance learning. ¹⁴

In an eye-tracking study of Google search results, the search-engine optimisation company Moz found that a result containing an image attracted more attention than one without an image. ¹⁵

Rapid recognition and memory

A study found that images could be identified after exposure lasting as little as 13 milliseconds. ¹⁶

Recognition tests found that people could remember more than 2,000 pictures with at least 90% accuracy after short presentation periods. ¹⁷

Pictures are generally remembered better than words, a phenomenon known as the picture superiority effect. ^{15, 18} Infographics also draw on pattern recognition and contextual comparison: showing variables against each other can make the magnitude of an effect apparent. ¹⁸

Information architecture

Information architecture uses design to structure unorganised information. ¹⁸ The Data-Information-Knowledge-Wisdom cascade describes how communicators organise information and audiences interpret it. ^{18, 19}

1. Unstructured information is organised into observations represented by numbers and words: data generation.
2. Data are structured with visual elements to reveal patterns and form meaningful content.
3. The audience relates that content to memories and experience to construct knowledge.
4. The goal is wisdom: a deep understanding that can be applied in other situations.

^{18, 19}

The cascade represents this progression as decreasing information entropy and increasing value. ¹⁹ Information architects facilitate knowledge construction, as medical writers do when making complex information accessible to a wider readership. ¹⁸ Communicating simply does not necessarily mean losing information. ¹⁸