Originally posted 2018-11-05 06:10:44.

The Dunning-Kruger Effect and Scuba Diver Over-Confidence

As a scuba instructor, one of my biggest qualms is certifying individuals with an over-confident mindset.  Confidence is good… for scuba diving, it is an important factor in countering apprehension and potential panic.  However, confidence must be based on a realistic appreciation of one’s abilities.  Lack of experience prevents scuba divers from making that realistic assessment and can lead to divers undertaking dives that are beyond their capabilities – an unsafe situation.

This tendency is explained in psychology as the ‘Dunning-Kruger Effect’ – a concept proposed in 1999, by Cornell Psychologists David Dunning and Justin Kruger, in their paper “Unskilled and Unaware of It: How Difficulties in Recognizing One’s Own Incompetence Lead to Inflated Self-Assessments“.  That paper won them the  2000 satirical Ig Nobel Prize in Psychology.

The “Dunning-Kruger Effect” is described as

“…a cognitive bias (a mental prejudice that affects ones judgement) which leads unskilled individuals to feel much more confident and certain about their skills or knowledge of a given subject than they should. This usually leads the afflicted to unjustifiably rate their own abilities much higher than average and to be blind to their own mistakes”.  Wikipedia

Not Knowing What You Do Not Know

In short, there is a tendency for less experienced divers to ‘not know, what they don’t know‘.  From my experience, it is primarily observed amongst divers making a significant step-up in training level;  entry-level Open Water qualification, graduation as a Divemaster and initial Technical Diver certification.

Knowing What You Do Not Know

Ironically, it is more typical for the diver to re-evaluate their competency as they gain experience at the new level.  This process may involve the opportunity to further compare themselves against a more appropriate peer group at their new level, and/or through the eventual revelation that considerably more knowledge and capability exist beyond their latest step of progression. It is normal for divers conducting such a re-evaluation to lower their perceived abilities accordingly.

In studies, these more experienced people tend to rate their abilities lower than a novice would.  Expert divers also tend to have lower confidence levels than novices, although higher than intermediately experienced divers, they are acutely aware that they still have much to learn.  This subsequent transition might be described as a process of  “knowing that you do not know“.  Some divers, however, do not experience that revelation.

Scuba Diver Confidence and Self-Assessment

Graph illustrating the Dunning-Kruger Effect

The Impact of Dunning-Kruger Effect on Scuba Divers

Based on their studies and trials, Dunning and Kruger proposed that, for a given capability, incompetent people have a tendency to:

  1. overestimate their own level of competency;
  2. fail to recognize genuine competency in others;
  3. fail to recognize the extremity of their inadequacy;
  4. recognize and acknowledge their own previous lack of skill, if they are exposed to training for that skill.
Let’s examine these in more detail, from a scuba diving perspective:

Over-Estimating Personal Competency


Failing to Recognize Competency in Others


Failing to Recognize Extremity of Inadequacy


Training Leading to Recognition and Acknowledgement of Previous Skill Deficit


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