Why Your DET Score Won't Move — 5 Thinking Mistakes Keeping You Stuck

A student came to us last month after taking the DET for the third time. She'd studied more than ever — new vocabulary lists, grammar exercises, two hours a night. When her score came back five points lower than the previous attempt, she said: "What's wrong with me?"

Nothing was wrong with her English. She was making five thinking mistakes that had nothing to do with the language itself. Every one of them was about how her brain processed the exam under pressure. And she's not unusual — we see the same five mistakes in almost every student who's taken the DET more than twice without the score moving.

Here's what they are and what to do about each one.

Mistake 1: Describing What You See Instead of Interpreting What It Means

You look at the photo, describe everything in it — the woman, the coffee, the phone — and feel good about it. Grammar is fine. Sentences are clear. Then your score comes back and nothing changed.

The DET's scoring AI doesn't reward description. It evaluates content development and discourse coherence — whether you develop your ideas and connect them logically. Listing objects in a photo doesn't develop anything. It's inventory, not thinking.

The distinction matters because you already interpret photos in your first language without trying. You see a woman alone at a café staring at her phone and your brain automatically generates meaning — maybe she's waiting for someone, maybe she just got a message that upset her. That's interpretation. But when you switch to English under time pressure, your brain drops into safe mode and starts listing instead.

For a deeper look at this technique, see our guide on the storytelling method for Write About the Photo.

Mistake 2: Freezing When You Lose a Word

You know what you want to say. You start talking. Then you lose a word and your brain just stops. The timer keeps going. You're watching the clock, panicking internally, and nothing comes out.

The frustrating part is that this doesn't happen in normal conversation. You speak English well with friends, with teachers, in low-pressure situations. But the moment there's a countdown on screen, your brain shuts down.

This is a cognitive load problem, not a vocabulary problem. Research on second language performance under time pressure shows that when the demands of a task exceed your working memory capacity, performance drops — regardless of your actual language ability (Chen & Chang, 2009). The DET is designed to create time pressure on every task. If you don't have a system for what to do when your brain stalls, the pressure overwhelms your processing capacity and you freeze.

Most students try to fix this by learning more words, thinking a bigger vocabulary bank will prevent the freeze. It won't. The freeze isn't caused by missing vocabulary — it's caused by having no fallback structure when retrieval fails under pressure.

We wrote a full breakdown of why this happens and how to train through it: Why You Freeze on DET Speaking.

Mistake 3: Writing What's Correct Instead of What's Clear

You sit down for Write About the Photo and your brain says: don't make a mistake. So you write safe, short sentences. Template phrases you've memorized — "first and foremost," "there are many advantages and disadvantages." No errors. Feels solid. Score doesn't move.

The DET is not IELTS. It's not TOEFL. Those tests have specific marking criteria where formulaic language can earn points in certain categories. The DET evaluates lexical diversity and lexical sophistication — meaning it measures whether you use a range of precise words in context, not whether you've memorized impressive-sounding phrases (Duolingo English Test — Understand Scoring). Recycling the same templates across every response scores low on both of those criteria, even if every sentence is grammatically perfect.

We had a student who wrote flawless English on every DET attempt. Could not break 95. Turns out the templates were his exact problem — he was hiding behind phrases he'd seen online instead of actually responding to the prompt. When we removed the templates and had him write what he actually thought (messy grammar and all), his score jumped 15 points.

Mistake 4: Studying English Instead of Studying the Test

Your English is genuinely improving. You're reading articles, watching shows with subtitles, journaling every night. Friends notice. Teachers notice. Then you take the DET and the score hasn't moved. You're confused because you know you got better — but the test isn't reflecting it.

The DET is a computer-adaptive test. It adjusts the difficulty of each question in real time based on your previous answers — answer correctly and the next question gets harder, answer incorrectly and it gets easier (Times Higher Education — Understand the DET Score). Each task measures how comfortably you use English under specific time constraints, not how much English you know in general.

The C-test (fill in missing letters) tests prediction speed. Read Aloud tests real-time processing — how fast language goes in through your eyes and out of your mouth. Interactive Writing tests spontaneous production under a countdown. These are performance skills, not knowledge skills. Getting better at English doesn't automatically make you faster at performing under these conditions, just like getting stronger doesn't automatically make you better at boxing.

For a complete DET-specific preparation plan, see How to Prepare for the Duolingo English Test.

Mistake 5: Looking at Your Overall Score Instead of Your Subscores

You got 105. You needed 110. So you study everything. Three months later, same score.

Your overall DET score is the average of four subscores: Literacy, Comprehension, Conversation, and Production. One weak area drags everything down — but if you're only looking at the overall number, you can't see it.

If your score is stuck in the 90–100 range specifically, we broke down the three exact gaps that cause that plateau — and how to identify which one is yours: DET Score Stuck at 90–100? Here's Why.

What Connects All Five

None of these mistakes are about English ability. They're about thinking under exam conditions — describing instead of interpreting, freezing instead of continuing, playing safe instead of thinking clearly, studying generally instead of training specifically, and looking at one number instead of four.

The students who break through don't prepare for English. They prepare to think in English under time constraints. That's a different skill, and it's trainable.