Recently, simple and flat designs in iconography have emerged and become a trend. However, are simple icons superior to complex ones? Prof. Xiaoning Liang, Trinity Business School, Trinity College Dublin, and her fellow researchers use an EEG – an electroencephalogram– to examine the brain’s response to simple and complex icons and gain a greater understanding of users’ cognition and behaviours.

Back to the Basics: What icons do our brains prefer? By CoBS Editor Celine Sophie Lüdtke. Related research: Facing a Trend of Icon Simplicity: Evidence from Event-Related Potentials, Weilin Liu, Yaqin Cao, Xiaoning Liang, Robert W. Proctor, and Vincent G. Duffy, International Journal of Human-Computer Interaction, (2024).

Chinese languages are widely considered some of the most complex languages to learn—mainly due to the use of intonations that do not exist in most others – and also due to the script. Moreover, most languages use a phonetic script to represent speech sounds visually. The Latin alphabet and the even more simplified Hangul (Korean) script are great examples of phonetic scripts.

Chinese script, however, is based on a script of pictograms (signific script), which are single characters representing things or thoughts. This starkly contrasts the actual pronunciation of these characters, as they had to transcend different dialects across China. Through the use of pictographs, literate people across China, no matter which dialect they spoke, could understand written messages.

As found on oracle bones, a form of divination used in ancient China, the original character for “mountain” was depicted as three triangles, a simple drawing of three mountains standing next to each other. In simplified modern Chinese, the word “mountain” is drawn with three strokes: “山” –  for language learners, easily recognisable as a mountain. The limited complexity of the character intuitively makes it easier to remember and more recognisable. In comparison, the oracle bone character for “fish” was a simple drawing of a fish looking upwards with two fins and some scales. The simplified, modern Chinese character “鱼” needs a little more fantasy to recognise a fish and needs a little more practice.

But why would we care about the simplicity or complexity of Chinese characters unless we want to learn Chinese? The answer – pictographs have made a comeback in communication: Emojis are essential in informal text messages, and icons in apps aim to showcase the app’s functionality. In this light, Trinity’s Prof. Liang et al. focus on understanding how complex versus simple design styles influence user cognition and behaviour.

Simple: Is it always better?

But what are the characteristics of the visual complexity of an icon? The complexity of an icon is primarily determined by the number of components it features. In other words, as an icon contains more elements, its visual complexity increases correspondingly. And despite aiming to provide necessary details for icon cognition, complex designs may hinder the functionality and usability of icons. As such, Xiaoning Liang and her colleagues focused their research on understanding how the two design styles – simple and complex – influence users’ cognition and behaviour.  

Indeed, previous research has examined the effect of perceived complexity on cognition, revealing that reaction times were shorter for simple icons but showed no difference in error count. Furthermore, both young and old participants used complex icons more efficiently, whereas younger participants favoured simple icons aesthetically. Other research compared 2D and 3D icons for user attention and efficiency during recognition. Its findings show that 3D icons outperformed 2D icons in terms of attention distribution and attraction. However, from an ERP (event-related potentials) perspective – measuring neuronal response to external stimuli – there is little knowledge about whether or why one icon design style might be better than the other.

Exploring the world of icon design

The researchers see ERPs as a useful tool in uncovering an individual’s perception and attention in response to external stimuli, with previous studies having effectively applied the ERP technique to explore the effect of icon design on icon cognition. By conducting these studies, the researchers found that an increase in familiarity with icons also increases attention to the relevant stimuli and that app icons with anthropomorphic features were perceived as more attractive, showing an attention bias for these app icons.

Another key indicator researchers have considered is reaction time (RT), which shows that search time can affect the allocation of attention to distinguishing features of app icons. The RT includes the time for the sensory receptors to receive the information of the stimulus, the time for cognitive processing in the brain, and the time for completing the response to the stimulus. Liang et al. provide invaluable additions to this research in focusing on the effects of simple and complex icons on our thinking.

Understanding how our brains think

Human cognition and behaviours are the consequence of neural activity in the brain. “Event-Related Potentials” (ERPs) are brain responses to stimuli measured via electroencephalography (EEG).

The brain is constantly generating electrical activity, which is measured by EEG as brainwaves. These waves oscillate between positive and negative voltages around a baseline, which is the voltage level shown on the EEG before a stimulus is introduced. When a stimulus is introduced, the brain activity may change compared to the baseline. A positive-going potential indicates that the voltage difference becomes more positive relative to the baseline. Here, the term “potential” refers to any measurable voltage difference.

Against this background, ERPs represent reliable indices reflecting the different information processing stages. Each ERP is a distinct response from the brain at a specific time window following the stimulating event. P1 is the earliest at 100 – 150ms post-stimulus, followed and overlapped by P2 (180 – 200ms), P3 (which is elicited by infrequent or novel stimuli), and Late Positive Potential (LLP), typically peaking between 300 – 800ms.

During P1, thought processes involving the earliest visual processing and allocation of attention resources take place. In P2, visual processing is more complex and emotions and attention are aroused. The LPP, which in the context of Liang et al.’s research is defined as the positivity after P2, deals with higher-order cognitive functions such as the perceptual level evaluation of a stimulus.

Measuring brain activity

Prof. Liang and her fellow researchers conducted an ERP experiment to assess human cognition and behaviours when confronted with simple and complex icon designs. They selected 18 right-handed participants with no history of neurological or psychiatric illnesses and who had not consumed any alcohol or medication within 24 hours prior to the experiment for their study.

In essence, the researchers showed the participants 17 different, easily recognisable icons in a simple and complex design version. The complex design had extra details, such as gradation and highlighting, while the simple design had a monochrome background. The EEG recorded their brain’s reactions, whereby the electrodes were placed in an expanded version of the international 10-20 electrode placement system, allowing separate ERP analysis of the frontal, central and parietal sites. 

In a second, separate set of the experiment, Liang and her colleagues posed the participants’ subjective “preference and usefulness” tasks: They had to judge how much they liked a design and how the icon helped them to extract information on a 7-point scale.

Pretty vs Practical: Subjective evaluation of icons

In their experiment, the researchers did not assess any significant preferences for simple or complex designs. However, the participants rated the simple icons more useful than complex ones for extracting information.

These findings support “cognitive load theory” in which a user’s working memory has limited capacity, while their long-term memory is unlimited. This implies that when presented with an icon, the individual uses their working memory to process information and retrieve patterns from their long-term memory. Due to the limited capacity of working memory, simpler icons that require less cognitive processing are therefore easier to understand, as they reduce the cognitive load.

Simple icons – a no brainer?

Overall, the researchers found in their experiments that the icons’ design complexity does not affect deep cognitive processing (LPP) but influences early attention allocation and visual processing (P1 and P2.)

In the P1 phase, the early visual processing and attention allocation phase, the icon design significantly affected P1 amplitude – complex icons showcased a larger amplitude, suggesting that they require more initial visual processing in the brain.

When Prof. Liang and her colleagues assessed the P2 ERP, which is responsible for more complex visual processing, they found that the icon design did not significantly affect P2 amplitude. Nonetheless, the parietal region of the brain, responsible for spatial processing, showed a larger amplitude when confronted with more complex icons, suggesting a higher activity in this region. Moreover, it showed a longer P2 latency for complex icons, as it was slower to process them.

The deep cognitive processing component, concerned with higher-order cognitive processing, did not show any differences in terms of processing time or activation for complex and simple icons, though the experiment showed that the central and parietal areas of the brain were more engaged in processing the icons than the frontal area, while the higher-order processing time was faster in the parietal regions of the brain. Overall, deep cognitive processing is not affected by the icons’ design.  

“Good design is good business”

Thomas Watson Jr.’s famous quote seems to hold true: Prof. Xiaoning Liang et al.’s study shows that designers should give preference to simple icons with a limited amount of features as they require fewer attention resources and induce more positive emotions.  

Furthermore, considering the elevated cost of designing complex icons vis-à-vis simple ones, the researchers suggest that simple icons should be given priority in mobile apps.

Useful links:

• Link up with Prof. Xiaoning Liang on LinkedIn
• Read a related article: Customer referencing – turning the client into a credible source of value
• Discover Trinity Business School, Trinity College Dublin
• Apply for the Trinity MBA.

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