## Gestalt principles hindered my sudoku performance

Last week, while waiting for friends, I picked up a community newspaper in hopes of finding a puzzle to help me pass the time. I found a sudoku puzzle.

A sudoku puzzle consists of nine 3×3 squares, sprinkled with a few starter numbers. The player must fill in all the blanks by referring to the numbers that are already filled. A number can only occur once in each row of 9, each column of 9, and each 3×3 square.

I regularly complete difficult sudoku puzzles, but this easy one—more starter numbers makes the puzzle easier—was taking much longer than I expected.

I soon realised that my slow performance was due to a design decision by the graphic artist!

In the original puzzle, shown at left, the graphic designer used  shading  for all the starter numbers. In my reformatted version, on the right, I used shading to separate the 3×3 squares. Both puzzles also use thicker lines to separate the 3×3 squares.

The shading for starter numbers, on the left, is unfortunate because it interferes with the player’s perception of the nine 3×3 squares. Instead, players perceive groups of numbers (in diagonals, in sets of two, and sets of five).

I assume the designer’s intention was to help identify the starter numbers. Regardless of the designer’s intention, the human brain processes the shading just as it processes all visual information: according to rules that cognitive psychologists call gestalt principles. A sudoku player’s brain—any human brain—will first perceive the shaded boxes as groups or sets.

In sudoku, the grouping on the left is actually meaningless—and counterproductive. However, since the brain applies gestalt principles rather involuntarily and at a low level, the grouping cannot easily be ignored. The player must make a deliberate cognitive effort to ignore the disruptive visual signal of the original shading. This extra effort slows the player’s time-on-task performance.

You can check your own perception by comparing how readily you see diagonals and groups in both puzzles above. On the left, are you more likely to see two diagonals, two groups of five, and many groups of two? If you are a sudoku player, you’ll recognise that these groupings in the puzzle are irrelevant to the game.

If you like, you can print the puzzles at the top, and give them to different sudoku players. Which puzzle is faster to complete?

Interested in gestalt principles? I’ve blogged about the use of gestalt principles before.

## Designing and influencing user performance

When designing the user experience of software, UX- and Development teams often focus on how the user interface supports user performance, because that’s within their locus of control. Once the product is in the wild, environmental factors may reduce user performance despite the team’s best product-design efforts. But I believe it’s possible for a UX team to also influence the environment in which their products get used. Consider two of these:

• The user’s display size.
• The soundscape.
##### Large displays < one salary

Users of all ages and genders are more effective at performing search tasks and comparison tasks (Tao Ni et al, 2006), and more effective at spatial tasks, when they use large displays. Mary Czerwinski et al, reported a 12% significant performance benefit (2003). However, when given a choice, people don’t want very large displays on their office desks; they opt for medium-sized displays instead. One study showed that older users least prefer large displays but stand to gain the most performance benefit. (This study was done before multi-monitor arrangements became common.)

A 12% improvement in performance suggests that 7 people with large displays could theoretically do the job of 8 people with medium displays. How many large displays could your office buy for one person’s salary every year? For business-to-business sales and especially for enterprise-wide software implementations, there’s a place for sales teams and proposal writers to mention the business case for larger displays.

Call it what you want—innovation, thinking outside the box, providing solutions—your UX-Design team can work with the Sales and Service/Implementation teams to ensure customers get solutions that include better hardware choices.

A half-decade of research by Dr Sabine Schlittmeier has expanded on what common sense told us: it’s harder to concentrate when others are chatting in the background. Schlittmeier found that when background speech is louder and more intelligible, it negatively affects verbal short-term memory, sustained attention, and verbal-logical reasoning. When I asked her what techniques have been shown successful, Schlittmeier told me that a masking sound, such as music or talk radio, is not objectively effective because the higher level of background sound has detrimental cognitive effects, but subjectively people feel this is effective. She added that there’s a measurable benefit to:

• Shifting high-concentration work to times when fewer people are around.
• Doing high-concentration work in single offices.

I suppose working remotely—from a quiet home—is a variation of these solutions.

I also asked, “What one thing, if handled differently, would most improve the way people experience noise at work?” Schlittmeier said it’s not about one thing. She recommended attacking problem sound from all dimensions at once: loudness, frequency characteristics, sound production, transmission, and so on.

The way I read the research results, reducing background speech to a soft, unintelligible noise could result in a 10% to 25% decrease in memory errors and logic errors, and an 18% increase in attention span. What Schlittmeier hasn’t provided is data about overall productivity improvement, without which it’s harder to make a business case for spending on office-noise abatement.

But there are other ways to mitigate the background office noise that affects your users, and you may be able to influence how your customers approach that problem.

Again: call it what you want—innovation, thinking outside the box, providing solutions—your UX-Design team can work with the Marketing team to influence the environment through traditional marketing. Imagine a business-to-consumer product that is designed to work even better with a (noise-cancelling) headset—and which is depicted in use with headsets in the marketing messages and on the packaging.