Tips for better science images

In this post I to discuss how to make the most of two types of figures commonly seen in scientific papers.

The first type is, of course, figures with data (Figure 1). These contain graphs and images showing the results and while not more important than the data itself, it can make a huge difference in how easy to read your data is. The less figuring out the reader has to do, the more likely they will understand the paper, the more likely they will remember, use and cite it. And if it is a reviewer reading it, the more likely they will feel positive about the content, and that’s never a bad thing!

Figure 1. Fragment of a figure from one of my papers.

• 1A. The same type of graphs within a figure should be the same size and style.

• 1B. Align axes both vertically and horizontally.

• 1C. Make sure the font size is legible. Make fonts larger than you think is necessary as usually figures are shrunk when published/inserted into the text.

• 1D. Make sure any images are high enough resolution not to be pixelated and magnified enough that what you are describing is clearly visible. Using callouts or insets is very useful here, as well as arrows.

• 1E. And, for the love of science, add scale bars to your microscopy images!

The second type is drawn illustrations, such as summary figure images, mechanism schematics or methodology summaries in grant applications. A good summary figure is likely to be used by others in presentations, reviews etc and can vastly increase the chances of your paper being cited. A clear representation of methodology can improve your chances of getting that grant application approved! There are some tricks based on how the human brain tends to interact with visuals:

Colour (Figure 2)

Figure 2. Example of a signalling pathway from one of my papers.

• 2A. Elements of the same colour will feel associated. This is a useful trick to e.g. mark elements of the same signalling pathway in one colour making it immediately easier to follow.

• 2B. Generally use colour sparingly. Elements that only provide context and are not crucial to the story can be rendered in very light (desaturated or transparent) colours or even shades of light grey not to draw they eye. Pick 2-3 colours for the rest.

• 2C. This is to a large extent dependent on the cultural context, however it seems that it is convention now to mark negative factors/harmful things/disease states in red and positive factors/healthy states/helpful medication in blue. Red and green is another possible colour combination, but it is not ideal for colour-blind readers.

• 2D. When you’re more or less done, convert your image to grayscale to check for issues with contrast. This again is helpful for people with colour-blindness or other problems with vision and ensures that if your figure is printed in black and white it is still legible.

Structure and flow of information (Figure 3, Figure 4)

Figure 3. Illustration of methodology from a grant application. If you look at the negative space (marked with light green) you will notice that it could be improved as there's a large white space to the left of the mouse.

• 3A. In English, we tend to read from left to right and from top to bottom. Therefore, it’s easiest on the brain to follow this pattern when reading the flow of information in a schematic. A circular pattern can also be useful, just make sure the first step is on the left or the top.

• 3B. Be aware of negative space. Everything should be evenly distributed in the image. Leave enough breathing room for the image not to feel too crowded. Leave some small margins on all edges. This gives the image a clean look.

• 3C. Use callouts to preserve scale between elements.

• 4A. Rounded arrows are more pleasing to the eye than sharp angles.

• 4B. You can vary arrow thickness to create hierarchies in complicated schematics.

Figure 4. On the importance of arrows.

Text elements (Figure 5)

Figure 5. Illustration of the hypothesis in a grant application .

• 5A. Add numbers to the steps of a long and complicated pathway to guide the reader’s eye.

• 5B. Create hierarchy in text or differentiate between different text elements by using different font sizes or making some text bold or italic. Use max 2-3 different styles so that it is not too chaotic.

• 5C. Again, make sure the font size is legible.

My final tip: for excellent video tutorials on science figures check out BioRender, in which all these images were created!