top of page

A Pattern of Recognition - Plaid and Visual Processing

For my first blog post on this platform, I decided to throw back to our first podcast subject, plaid (thank goodness for show notes). I’m resurrecting this particular topic not only because it’s fascinating scientifically, but also because I came across an equally fascinating article in the BBC about tartans and modern tartan design.

So how are plaid and tartan related? Tartan is a description of the pattern, alternating bands of colored threads woven as both warp (the tightly stretched lengthwise fabric) and weft (transverse threads woven between the warp threads) at right angles from each. Plaid was originally a large piece of tartan cloth worn as a type of kilt or shawl but the word has since become synonymous with the pattern, at least in the US.

The earliest evidence of tartan is from a society from Central Europe and dates between the 8th and 6th centuries BC. Additionally, mummies in northwestern China have shown similar textile patterns. The tartan as we know it today appeared in the 16th century in Scotland. Although not until the late 17th or early 18th century was it a uniform pattern. The link between clans and tartans is thought not to have been strict until the 19th century.

While the historic nature of tartans continues and there is a Scottish Registrar of Tartans, what I learned recently was that there are modern tartan designers and that this singular pattern is far from old and fussy. In an article for the BBC, Norman Miller highlights the world of modern tartan design. This is the sort of thing that I love, continuing a tradition with a modern twist.

Many of the new tartan designs get their inspiration from societal and historic issues. This includes on designed for the COP26 meeting. It was designed by Brian Wilton and the base colors tell an interesting story. A scientist named Guy Stewart Callendar is considered the first person to link carbon dioxide in the atmosphere with human activity, namely the industrial revolution. Wilton used the similarity with Callendar’s surname and the Scottish town of Callander as the starting point for his design. Callander is in an area of Scotland dominated by the MacGregor clan. Their tartan is blue, green and white so those are the starting colors for the COP26 tartan design.

To these base colors, Wilton added a weaving design that resulted in “glowing points of brightness that look like miniature suns on a new dawn”. Additionally, the tartan uses recycled wool from a textile recycling plant in Tuscany. The layering of these design elements and inspirations is part of what makes tartan so special and so appealing. There seem to be an infinite number of color and shape patterns.

It’s these color and shape combinations that scientists are interested in. As I mentioned in the podcast episode, scientists used plaid (tartan) as a test pattern when researching how we see. Specifically, plaids are used to help identify what processes are involved in spatial visual recognition. Using plaids, researchers have determined the grouping and the outputs of orientation spatial filters. These are component of the mammalian visual cortex that are involved with oriented lines and edges. So what does this mean.?

Human eyes filter out high spatial frequencies from the input they receive. They filter out spatial frequencies that would not be used by our visual processing systems and are essentially clutter. The plaid patterns have helped researchers determine that the spatial filters in human eyes are grouped and combined to achieve different visual perceptions (not just spread evenly over the whole eye, for example). Researching plaids has also led to a theory of motion detection that says motion direction and speed are processed independently in early visual processing.

Who would have thought that a relatively simple pattern could both provide some much creative inspiration and provide the basis to delve into the complex science around how we see? This is why I love science, it’s embedded in everything and helps us understand our world.


References:

2. Perception of Stationary Plaids: The Role of Spatial Filters in Edge Analysis. Georgeson MA and Meese TS. Vision Research (1997). 37(23) pp 3255-3271

3. Adaptive Filtering in Spatial Vision: Evidence from Feature Marking Plaids. Georgeson MA and Meese TS. Perception (1999). 28(6)

4. Characteristics of dynamic processing in the visual field of patients with age-related maculopathy. Eisenbarth W, et al Graefes Archive for Clinical and Experimental Ophthalmology (2008). 246(1): 27-37


bottom of page