Therapists, on average, do not improve with experience alone. Their outcomes stagnate or deteriorate. But they do not all follow the same trajectory. Some therapists do improve over time. Some deteriorate dramatically. Many stay at the same level they reached part way through their training.
Various factors contribute to this phenomenon. They can broadly be categorised as:
The nature of therapy;
The nature of therapists;
The nature of humans.
Each one is in some ways conducive to the gradual erosion of therapist performance over time. But each of these factors also offers clues as to how experience can translate into improved, rather than gradually deteriorating, outcomes. In this post I’ll lay out each of these factors and the research that supports them. In the next post, I’ll explore some possible solutions.
The nature of therapy
Therapy unfolds in a noisy environment in which the relationship between the therapist’s actions and client outcomes is hard to intuit (Tracey et al., 2014).
As such, therapy is not the sort of endeavour that is readily conducive to the acquisition of expertise, which requires timely, accurate feedback in response to one’s actions. A basketball player practicing free throws can immediately and somewhat objectively perceive the effects of an adjustment to their foot position, and know whether it is an improvement to retain. In a few hours they can gather a sample of hundreds of outcomes on which to base this, whilst holding other variables steady. For a therapist, feedback is less immediate (typically weekly at best), and any adjustment they make to their practice is one independent variable among innumerable.
So many factors influence client outcomes beyond the therapist, including client factors (age, motivation etc.) and extratherapeutic factors (events in the client’s life). Did the therapist’s particular focus on accurate empathy contribute to the client’s recovery, or did the client just feel better because they got a new job or the Strait of Hormuz reopened? Did the therapist’s implementation of the Compassion Focused Therapy skills they learned during a recent workshop make the difference for this client, or would the client have simply got better anyway, due to the natural cycle of their mood? In fact, research shows therapist factors (e.g. empathic ability and facilitative interpersonal skills) account for only ~5% of variance in client outcomes (Johns et al., 2019).
There are complex and unpredictable interactions between the therapist’s actions and the unique individual client. What works with one person may not with another. In other words, anything “learned” from working with one client may not be relevant to the next one, which makes it hard to accumulate expertise across clients, although this may occur in very specific circumstances. Leon and colleagues (2005), for example, found that, when clients on a therapist’s caseload were matched in pairs based on demographic and clinical characteristics, the second client in the pair attained better outcomes, but only if they started therapy less than 75 days after the first. This very tentatively suggests some evidence of accumulated expertise, but only between similar clients, and only when they are treated in very close temporal proximity. These conditions are often not met in clinical practice.
Indeed, “outcomes” in themselves are hard to intuit, and therapists are surprisingly poor at perceiving and predicting them from their subjective judgement alone. This may sound implausible, given therapists’ reputation for attunement, but without tracking outcomes, they often struggle to infer their client’s trajectory of change.
In one study, 49 therapists were asked to predict which of their clients (n=550) would deteriorate at the end of treatment (Hannan et al., 2005). They were told that the deterioration base rate is roughly 8%. The sample predicted that 0.1% of their clients (3/550) would deteriorate, compared with 7.2% (40/550) who did.
In another study, Østergård and colleagues (2024), asked therapists to predict, after each session, whether their clients’ CORE-10 score would improve/ deteriorate/ stay the same by the end of therapy. Before making predictions, participants were informed that 5-14% of clients typically deteriorate during treatment. The participants made 1140 predictions, out of which they made only eight (0.7%) predictions of deterioration. All of these were made for clients who actually showed no change. Not a single one of the clients who did deteriorate was predicted to do so. In predicting deterioration, the therapists performed no better than chance.
More remarkable still, after each session, therapists were asked whether they believed their client had improved/ deteriorated/ stayed the same (on the CORE-10) based on what they had seen during the session. The therapists still performed no better than chance. Clients showed deterioration in 83/1015 sessions. Therapists identified 6 (7.2%) of these accurately. They misidentified 50 (60.2%) as “no change”, and misidentified 27 (32.5%) as improved. A tipsy aardvark with limited psychotherapy training, reclining by a pool, blindfolded by cucumber slices and guessing with his tongue could have performed similarly.
Without outcome measures, therapeutic change is clearly hard to accurately infer. And if therapists can’t accurately infer change, how can they adjust suitably in response? Unhelpful adjustments may be reinforced by inaccurate inferences about their effects.
Notably, these inaccurate inferences are all one way. The studies above demonstrate a systematic overoptimism bias—an erroneous belief that barely any clients will deteriorate, and indeed that clients have not deteriorated, even when they have.
Yet despite all these challenges, all this uncertainty, and all the limitations of their intuition, therapists are often very confident about the effects of their interventions.
The nature of humans
But what’s wrong with confidence? Surely confidence reflects the gradual (and hard-earned) accumulation of competence over time? In fact, there is often a mismatch between confidence and competence. In therapy, as in medicine and driving and knowledge of firearms (Dunning et al., 2003), people exhibit a tendency to overestimate their performance. Donald Trump is a very confident man. The most confident.
Therapists, similarly to other humans, exhibit a strong bias towards overrating their effectiveness. Walfish and colleagues (2012) asked a sample of American therapists to rate their performance relative to other clinicians. Every single therapist rated themselves above average. On average, the therapists rated themselves in the top 20%. Only 8.4% of the sample rated themselves below the top 25%.
A similar study with a British sample found similar, albeit more moderate distortions, with therapists rating themselves, on average, in the top 35% (Parker et al., 2015). In a study that compared therapist self-ratings of a session recording with the ratings of an independent rater, Brosan and colleagues (2008) found that the the less competent therapists were more prone to overestimate their abilities.
Given this tendency of humans, and of therapists, to overestimate our competence, it is important to get independent feedback on one’s performance. However, this is exactly what therapists stop doing post-qualification. For example, 80.5% of a sample (n=72) of UK clinical and counselling psychologists said they rely exclusively on self-report during supervision (Nicholas & Goodyear, 2021), meaning no video or audio recordings played, meaning no direct feedback on their actual performance as therapists.
This is a huge missed opportunity, because direct feedback on one’s actual performance offers a possible pathway to improvement. Worse still, the absence of direct feedback may create the conditions in which performance can deteriorate over time. Given the pervasiveness of overconfidence and overoptimism biases, this is likely to occur beyond the limits of one’s awareness.
This overconfidence matters. Constantino and colleagues (2023), found that overestimation of one’s competence is associated with worse outcomes for one’s clients. Conversely, a more accurate self-evaluation, or an underestimation of one’s competence, was associated with better outcomes. Some research suggests professional self-doubt may be conducive to better patient outcomes in some domains (e.g. Nissen-Lie et al., 2013), although findings have been mixed (e.g. Jacobsen et al., 2026).
The longer therapists have been qualified, the better they rate themselves relative to other therapists (Parker et al., 2015). This would make sense if therapist outcomes improved with experience. But they don’t. As such, it could be hypothesised from this that therapists’ increasingly overrate themselves relative to others as they gain more experience.
Very few longitudinal studies have looked at the relationship between experience and self-evaluation. Gonsalvez and colleagues (2023) examined the difference between trainee clinical psychologists’ self-evaluation of their performance, and their supervisors’ evaluations at three points in the training journey. Initially, trainees substantially underestimated their performance relative to their supervisors’ evaluations. However, this discrepancy diminished at the second stage and reversed into an overestimation at the final stage, just before graduation. Would this shift towards overestimating one’s clinical skills continue to become more pronounced post-qualification? Given studies that have recruited qualified therapists show substantial overestimation of skills, this seems possible.
The nature of therapists and drifty drift
One possible link between experience, confidence and gradually deteriorating outcomes is “therapist drift”.
This is the tendency to drift away from the evidence based practices one was trained in. It is a phenomenon that has been noted across multiple contexts and modalities (e.g. Borntrager et al., 2013; Speers et al., 2022). There has been debate about how to define drift. One simple definition characterises it as deviation from evidence based protocols. However, research increasingly suggests that personalisation of treatment improves outcomes (e.g. Nye et al., 2023). As such, this narrow definition of drift has been reframed by some authors as a reflection of “good clinical judgment and a commitment to personalized patient care” (Yonatan-Leus & Tishby, 2025). But therapy can be personalised and remain evidence based (e.g. Moskow et al., 2023).
As such, I’m going to refer here to “drifty drift”, which I’ll define as deviation from evidence-based principles, not protocols. Examples of “drifty drift” would be a psychodynamic psychotherapist avoiding the exploration of transference patterns, or a CBT therapist not implementing exposure for anxiety-related problems, due to beliefs that it will be uncomfortable for clients (Scheveneels et al., 2025), or that one can simply rely on intuition to come up with something better (Gaudiano et al., 2011).
There is some, albeit limited, evidence that therapist experience is linked with drift (Speers et al., 2022). For example, the recency of one’s degree was associated with greater use of evidence-based treatment in youth mental healthcare in the US (Cho et al., 2019), and across a range of psychologists in Australia (Hamill & Wiener, 2018). Waller and colleagues (2012) found that older, and more experienced therapists were less adherent to evidence based practice in CBT for eating disorders. A meta-analysis found that older therapists are less likely to utilise exposure therapy (Langthorne et al., 2023). The authors hypothesised that this could be related to older therapists being more confident and more reliant on clinical judgement than on the evidence base.
Several studies have suggested that experienced therapists are slower to learn new approaches. For example, Beidas and colleagues (2014) found that more experienced clinicians showed poorer fidelity to CBT for youth anxiety after training in the approach. Years of experience (and age) have also been associated with requiring extra training to reach necessary standards in motivational interviewing (Martino et al., 2011).
But a link between greater experience and slower learning of new approaches does not necessarily explain why therapists don’t improve with experience. An experienced therapist could, in theory, continue to improve in their original modality, even if it takes them longer to learn new approaches.
Another possibility is that, as time elapses after one’s training, knowledge fades. This is borne out by a study that found experienced therapists (10 years of clinical experience or more) performed significantly worse than trainees on tests of knowledge, case conceptualisation and treatment planning (Vollmer et al., 2013).
Taking this a step further, is it possible that, as one undertakes more CPD, and picks up new models throughout one’s career, this new knowledge inhibits the retrieval of the old knowledge and training. For example, could it be that my head is so full of recent CFT and DBT and EFT and CAT trainings that it does not consistently and comprehensively, across treatment, retrieve and deploy exposure, for example, in its full and glorious simplicity? Maybe I can’t see the wood for all the -Ts. Maybe I am so intent on making my garden look great that I spend all my time and effort accumulating fancy new gnomes at the expense of attending to the plants that made it a garden in the first place.
Conclusion
Improving therapeutic outcomes is hard. Therapists who wish to do so face many challenges. To summarise…
It is difficult to infer outcomes. In the absence of measures, therapists are overoptimistic about change, both prospectively and retrospectively. They tend to be overconfident about their effectiveness, and this overconfidence potentially grows with experience. Overconfidence can lead to drifty drifting away from evidence based principles, towards watered down, less effective interventions. These issues can gradually erode therapist performance over time. But this doesn’t have to be the case.
Although much remains to be understood about why therapists don’t improve with experience, much is already understood about how they can improve with experience. That will be the topic of the next post.
Did I miss anything?? Share your thoughts in the comments!
Maybe I can’t see the wood for all the -Ts
That is a funny line! Interesting article, I'm curious where you're going with it!