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A mental filter tracker for the one bad detail that discolors the whole day

One critical comment survives a day full of fine ones. Mendly logs the moment a mental filter kicks in — the single detail that gets dwelt on while everything else quietly disappears — with one tap, no gray-area exercise required. Hourly patterns later show what kinds of details tend to take over.

The research

David Burns named the mental filter, describing it with a specific image: 'a single negative detail... like the drop of ink that discolours the entire beaker of water.' The rest of the day's evidence isn't weighed against the detail — it's simply not registered. Mendly's tap-to-log exists to catch the moment the filter engages, before the rest of the day gets discolored along with it.

— David Burns, Feeling Good, 1980

Want to understand why this happens? Why do I overthink at work? The research on rumination on the job

Quiz

What's your mental-filter pattern?

Question 1 of 4

When does the filter usually engage?

“The mental filter isn't really about negativity. It's about which single data point your attention decided was representative — and that decision happens before you're aware it's being made, which is why arguing with the conclusion rarely works.”

Features

One-tap logging

One tap marks the thought — no typing, no prompts. The friction is so low it actually works mid-meeting, mid-walk, mid-spiral.

Milestone badges

16 badges that celebrate your awareness, not your perfection. First Catch, Streaks, Early Bird, Voice Found — each one earned.

Shareable cards

Daily summary cards designed for Stories. Share a win without oversharing.

Not quite your pattern? A should-statements tracker for the rule that shows up before the reasoning does might fit better

Apps like MindLift ask you to list the positive details you're filtering out as you log the thought. If you already know the concept, generating that list in the moment the filter is active is exactly the hardest time to do it. Mendly logs the moment and leaves the listing for later, if at all.

See the full comparison

Common questions

I already know this is called a mental filter. What does tracking add?
A record of which kinds of details tend to survive the filter — critical feedback, a specific person's tone, a particular type of mistake — and how often, which is more specific than the general observation that you dwell on the negative.
Is this a CBT app?
No. There's no positive-evidence worksheet or gray-area exercise. Mendly logs when the pattern occurs and shows you the timing — a complement to CBT work, not a version of it.
How is this different from the all-or-nothing thinking app?
All-or-nothing thinking collapses a situation into total success or total failure. A mental filter is narrower — it's one negative detail excluding everything else, without necessarily flipping the whole situation to 'failure.' The two often travel together but aren't identical.
What does the free trial include?
The full app, no restrictions, for 7 days. After 7 days you choose monthly ($7.99) or annual ($59.99, about $5/month). Cancel anytime via your Apple subscriptions — no emails required.
A stress thought tracker for when the event is over but the thoughts aren'tAn emotional reasoning tracker for the feeling that insists it's a factWhat is rumination? The psychology behind repetitive negative thinking

See for yourself — 7 days free.

Try Mendly on iPhone. Cancel anytime via Apple subscriptions.

Download on theApp Store