Biases – Gotta Know Them to Overcome Them!

Excerpt from: Manual Muscle Testing – Art and Science: An Exploration of its History, Physics.Mechanics, and Utility in Practice. Muscle System Consortia, 2016 (Dunn K., McMillin C., Mack G.)

One must strive to acknowledge and manage the effects of bias that lead to the misunderstanding of the relationships between events.

bias (n). Prejudice in favor of or against one thing, person, or group compared with another, usually in a way considered to be unfair: there was evidence of bias against foreign applicants; the bias toward younger people in recruitment | [in sing.] a systematic bias in favor of the powerful- [in sing.] a concentration on or interest in one particular area or subject: he worked on a variety of Greek topics, with a discernible bias toward philosophy. – [STATISTICS] a systematic distortion of a statistical result due to a factor not allowed for in its derivation. (40)

“To know the true reality of yourself, you must be aware not only of your conscious thoughts, but also of your unconscious prejudices, biases and habits.” (50)

The following represent key biases that need acknowledged and managed when; setting up, making observations during, taking measurements of, and interpreting the results from, the exercise assessment and testing:

  1. The Identity Narrative Bias
  2. Confirmation Bias
  3. Association Bias
  4. Availability Bias
  5. Representative Bias

Individual Identity is a Narrative Construct:

THE MISCONCEPTION: One makes sense of life through rational contemplation.

THE TRUTH: One makes sense of life through narrative.


If your professional life narrative holds the perspective that everything surrounding the body’s ability to move and maintain positions via its control over joints comes only from skeletal muscle then your only conclusion when you see a problem with motion or position be due to muscle. What could be wrong with the muscle?

Anecdotes as the ground level experiences that lead to and reinforce a particular narrative.

The Narrative is protected and sustained through the following list of cognitive biases (2 – 5 above):

Confirmation Bias:

THE MISCONCEPTION: Your opinions are the result of years of rational, objective analysis.

THE TRUTH: Your opinions are the result of years of paying attention to information that confirmed what you believed, while ignoring information that challenged your preconceived notions. See narrative bias.


Supine Hip Flexion Limited due to __________so_________the _________. This bias leads the practitioner to skipping something, or going right into doing something without checking, or manipulating something to get the answer they want.

Association Bias:

A cognitive bias that results from an external stimulation that triggers a memory that is then reconciled with the stimulus but that may have no valid connection to the stimulus.A cognitive process that isreflexive in nature andnon-conceived resulting in a superficial conclusion between the two or more items being associated that their correlation creates equivalence between some property and characteristic. A.k.a. linking or correlation bias.


When you see supine hip flexion limited you remember that a previous client(s) that had that limit you did such and such and that worked so that will work today with this client and you do it without considering other options.

Availability Bias:

A cognitive bias where individuals make inaccurate predictions regarding the frequency of an event within a population based largely on limited experiences. This errant estimation as to the probabilities of events is then excessively weighted in resulting judgments.


Exercise professional observations of supine hip flexion are typically limited to a population who are supposed to be apparently healthy individuals. They would not attribute the limit to other reasons other than what they would expect from their previous observations of apparently healthy people from within their own practice experience.

Representative Bias:

A cognitive bias where individuals make potentially inaccurate categorizations based on too few observed characteristics.

Example: A practitioner observes a small number of limited supine hip flexions and categorizes all observed limitations in supine hip flexion as _____________.