Case Formulation Mistakes Psychologists Make (And How to Fix Them)
- Amanda Moses Psychology
- Apr 21
- 3 min read
Case formulation is one of the most powerful tools we have as psychologists. A strong formulation helps us understand our client’s distress, guide our interventions, and make sense of what’s working—and what isn’t. But it’s also something that many early-career psychologists struggle with.
Over the years, I’ve supervised dozens of provisionals, and the same issues come up time and time again. So, let’s talk about some common case formulation mistakes I see—and more importantly, how to fix them.
1. Jumping to Diagnosis Without Understanding the Problem
One of the biggest mistakes is prematurely anchoring to a diagnosis without understanding what’s actually happening for the client.
Let’s say a client presents with low mood, fatigue, and loss of interest in activities. It’s tempting to jump straight to “depression.” But what if the low mood is due to burnout? Or grief? Or a medical condition? Without a proper formulation, we risk treating the wrong thing.
💡 Fix it: Focus on what’s driving the distress—not just what the symptoms are. Ask: What maintains this pattern? When did the symptoms begin? What’s reinforcing it? What’s the functional role of these behaviours or feelings?
2. Missing the Precipitating and Predisposing Factors
Too often, I see formulations that jump straight to “here and now” issues—without any exploration of what led to the current presentation. This can result in a shallow understanding of the client’s context and missed therapeutic opportunities.
💡 Fix it: Always include the 5Ps (Predisposing, Presenting, Precipitating, Perpetuating, and Protective factors). These aren’t just for CBT—they’re useful in any therapeutic model. Look at early developmental experiences, family dynamics, critical incidents, and systemic factors. Understanding what led up to the problem is just as important as what’s keeping it going.
3. Overlooking Reinforcement Cycles
One of the most teachable formulation moments I see is when we forget to identify why the behaviour continues. For example, a client with social anxiety might avoid events, which temporarily reduces distress. That relief becomes reinforcing, which means the avoidance is likely to continue—even though it reinforces the long-term problem.
💡 Fix it: Identify any short-term payoffs that maintain the problem. These are often subtle, like avoidance, reassurance seeking, or people-pleasing behaviours. Once you see the pattern, you can plan interventions that gently interrupt it.
4. Treating the Symptom, Not the System
Some formulations focus only on the most visible symptom and ignore the broader system the client is operating in. For example, focusing solely on a young person’s depressive symptoms without exploring family dynamics, trauma history, neurodivergence, or peer relationships will leave huge gaps.
💡 Fix it: Step back and take a systemic view. How do relationships, culture, neurobiology, trauma, or environmental stressors play a role? Treating a symptom in isolation rarely leads to lasting change.
5. Overcomplicating It (Or Oversimplifying It)
The final trap? Either making formulations so abstract they’re unusable—or so simple they don’t offer enough clinical guidance. I often see pages of vague psychobabble or, on the flip side, a one-sentence “formulation” that doesn’t tell me much more than the presenting problem.
💡 Fix it: Good formulations are like a working theory—they’re detailed enough to guide your intervention, but not so rigid they can’t evolve. I like to use clear headings (e.g., presenting issue, maintaining factors, strengths, treatment implications) and update them as therapy progresses.
Case Formulation Is a Skill—And You Can Get Better at It
Case formulation isn’t just for CBT. It’s a foundational skill that applies across therapeutic modalities. It helps us avoid assumptions, reduce reactivity, and work in a way that’s thoughtful, tailored, and ethically sound.
It’s important to remember that a case formulation is not just an opinion—it’s a clinically-driven hypothesis. That means it should be grounded in psychological theory, consistent with the evidence base, and shaped by the information you’ve gathered through assessment.
For example, let’s say you hypothesise that a client’s perfectionism is maintained by early attachment experiences and reinforced by current performance-based validation at work. That’s not a random guess—it’s a working theory built on known patterns in schema theory, developmental psychology, and behavioural models. It’s something you’ll test, refine, and adjust as therapy progresses—not something you’re plucking out of thin air.
💡 A good formulation is clear, collaborative, and evidence-informed. It’s not static—it evolves as the client grows, new information emerges, or treatment needs change.
Want Support with Case Formulation?
If you’d like support creating stronger, more structured formulations, I’ve got you covered:
🧠 My Therapy Manual Bundle includes clear examples, editable formulation templates, and real-world illustrations you can use in your own work.
🎓 My Case Formulation & Treatment Planning Clinical Resource breaks down formulation step-by-step, and includes a customisable and editable template—perfect for early-career psychologists or anyone looking to refresh their skills.
✔ Let’s stop guessing and start formulating with purpose.
