Interactive Trail Making Test (TMT) for Cognitive Control

What Is the Trail Making Test and Why Should You Care?

The Trail Making Test tests whether you can switch between different mental rules without your cognitive gears getting stuck.

This isn't just some random connect-the-dots exercise. It's one of the most widely used neuropsychological tests because it reliably reveals how well your brain handles cognitive flexibility, task-switching, and divided attention. These are the mental skills that determine whether you can smoothly adapt when situations change or if you get mentally locked into old patterns.

• Part A tests your baseline processing speed and visual scanning ability. Connect circles numbered 1 through 25 in order. Sounds simple, and it is — that's the point. This establishes how quickly you can perform basic sequencing without cognitive complexity getting in the way.
• Part B is where things get interesting (and potentially frustrating). You alternate between numbers and letters: 1→A→2→B→3→C and so on. Your brain has to constantly switch between two different sequencing rules while maintaining the overall pattern. This is cognitive multitasking at its finest.

This skill affects everything from following multi-step directions to adapting when your carefully planned day gets derailed. People with strong cognitive flexibility can switch between tasks smoothly, while those with weaker set-shifting ability tend to get stuck in mental ruts or struggle when routines get disrupted.

Some people naturally excel at mental flexibility. They can switch between different types of thinking, no problem. Others are more cognitively rigid — not necessarily less intelligent, but less adaptable when mental demands change rapidly.

How the Trail Making Test Actually Works

The Trail Making Test works by progressively loading your executive function with complexity until you can see where your cognitive flexibility starts to break down.

Part A mechanics: Connect numbered circles 1 through 25 as quickly and accurately as possible. This tests visual scanning (finding the next number among distractors), working memory (remembering what comes next), and processing speed (how quickly you execute the plan).

The circles are randomly scattered across the screen, so you can't just follow a predictable visual pattern. Your brain has to actively search, identify, and connect while maintaining the numerical sequence in working memory.

Part B complexity: Alternate between numbers (1, 2, 3...) and letters (A, B, C...) while maintaining overall sequence order. This requires cognitive set-shifting — your brain must constantly switch between two different ordering systems while tracking your position in both sequences.

The cognitive load here is substantial. You're not just connecting dots; you're managing dual task demands, inhibiting the natural tendency to continue with numbers, and maintaining mental flexibility under time pressure.

Mistakes typically fall into patterns. Continuing with numbers instead of switching to letters shows perseveration — getting stuck in one mental set. Losing track of position indicates working memory overload. Taking excessively long between connections suggests decision-making or visual scanning difficulties.

Completion time matters more than perfect accuracy. The test measures how efficiently your brain handles complexity, not whether you can eventually figure it out. Fast completion with few errors indicates strong executive function. Slow completion suggests cognitive inefficiency, even if you ultimately succeed.

What Your TMT Performance Actually Reveals

Your Trail Making Test results provide insights into several interconnected aspects of cognitive function, though it's important not to over-interpret single test performance. Now, this isn’t the official test. That’s because the real-deal TMT is done with pen and paper. 

Online/digital versions try to mimic this, but it’s difficult for an apples-to-apples comparison when you have varying screen sizes, desktop vs mobile, different contrasts and saturations, and the like. Some tests even aid the user by highlighting the next number or letter in the sequence. For me, that feels way too easy, so I refined it a bit for the user experience.

Now, for the results:

• Processing speed baseline: Part A performance shows how quickly your brain handles basic visual-motor tasks. This affects everything from reading speed to how efficiently you complete routine activities.
• Executive function capacity: Part B performance specifically targets cognitive flexibility — your ability to smoothly switch between different mental rules or task demands. This predicts adaptability in complex, changing situations.
• Attention and focus: Both parts require sustained attention and concentration. Poor performance often reflects difficulty maintaining focus rather than inability to understand the task.
• Working memory demands: Successfully completing Part B requires holding multiple pieces of information in mind simultaneously — your position in the number sequence, your position in the letter sequence, and the alternating rule itself.
• Cognitive efficiency: The ratio between Part B and Part A times reveals how much additional cognitive load affects your performance. Large ratios suggest executive function is a relative weakness compared to basic processing speed.

TMT doesn't assess intelligence, creativity, learning ability, or emotional intelligence. It's specifically measuring executive function and cognitive flexibility under time pressure.

Some people excel at Part A (fast processors) but struggle with Part B (poor set-shifting). Others show the opposite pattern. Neither indicates overall cognitive ability — they represent different mental strengths.

Strong TMT performance correlates with better multitasking ability, adaptability to changing demands, and efficiency in complex work environments. Poor performance might explain difficulties with tasks requiring mental flexibility.

Improving Your Cognitive Flexibility

While cognitive flexibility has genetic components, several strategies can help optimize your mental agility within your individual limits.

1. Practice task-switching: Deliberately switch between different types of activities throughout your day. Alternate between analytical tasks and creative ones, or switch between detail-focused and big-picture thinking. This builds mental flexibility gradually.
2. Learn new skills regularly: Learning new skills — especially those requiring different types of thinking — strengthens cognitive flexibility. Try alternating between learning a language and practicing a musical instrument, or switch between learning technical skills and creative pursuits.
3. Physical exercise matters: Cardiovascular exercise specifically improves executive function and cognitive flexibility. Regular aerobic activity increases blood flow to prefrontal regions responsible for set-shifting and task management.
4. Mindfulness and meditation: Mindfulness training improves cognitive flexibility by strengthening attention control and reducing automatic, habitual responses. Even brief daily meditation can enhance mental agility over time.
5. Challenge routine patterns: Deliberately vary your daily routines to prevent cognitive rigidity. Take different routes to work, try new problem-solving approaches, or intentionally break habitual patterns of thinking and behavior.
6. Sleep and stress management: Cognitive flexibility suffers dramatically under sleep deprivation and chronic stress. These factors particularly impair executive function, making set-shifting more difficult and error-prone.

Most "brain training" games that claim to improve cognitive flexibility don't transfer well to real-world mental agility. The improvements are usually specific to the trained task rather than general executive function enhancement.

You can probably improve your cognitive flexibility through consistent practice and healthy lifestyle choices, but dramatic changes are unlikely without addressing underlying factors like sleep, stress, or attention issues.

Test Your Mental Agility (Then Actually Use What You Learn)

The Trail Making Test isn't just about generating a score — it's about understanding how your brain handles cognitive complexity and task-switching demands.

Bookmark this page and test yourself periodically to see how factors like time of day, stress level, and mental fatigue affect your cognitive flexibility. Many people discover predictable patterns in their executive function performance.

Share this with people who struggle with multitasking, adapting to changing plans, or feeling mentally "stuck" in routines. Sometimes cognitive flexibility issues aren't personality traits — they're trainable skills that can be developed.

Want to assess other aspects of your cognitive function? Our working memory tests measure different aspects of executive function.

Your brain's ability to switch between different mental gears affects more of your daily life than you probably realize. Time to see how well your cognitive transmission actually shifts.