The Law of Primacy -

The Law of Primacy

Article by Mark Powell

Introduction

The law of primacy is one of Edward Thorndike’s laws of learning. All of his laws are relevant in some way to teaching scuba diving but in this article, I am going to focus on just this one law.

The law of primacy says that what you learn first sticks with you. This means that as instructors it is essential that we are teaching best practice right from the start.

Edward Thorndike and His Laws of Learning

Edward Thorndike was an American psychologist and pioneer in the field of educational psychology during the late 19th and early 20th centuries. He is widely recognized for his groundbreaking research on the learning process. Although there are some criticisms of his methods and conclusions, most educators recognize that his laws of learning still hold considerable value when considering why students learn.

Thorndike’s Three Primary Laws

The law of readiness – The student must be ready to learn.
The law of exercise – You need to practice in order to make anything stick.
The law of effect – Seeing your efforts giving the right result helps learning.

Three Additional Laws

The law of primacy – What you learn first sticks with you.
The law of intensity – Some pressure or realism is important but not too much.
The law of recency – We have stronger recall for the last thing that was mentioned.

All of these laws have an impact on how people learn and, by implication, on how we should structure our lessons. However, in this article, I am going to focus on the law of primacy.

The Law of Primacy: Key Principles

Things learned first create a strong impression.
What is taught must be right the first time.
“Unteaching” wrong first impressions is harder than teaching them right the first time.
What the student learns must be procedurally correct and applied the very first time.

Practical Implications of the Law of Primacy

If we look at realistic implications of these points we can see the truth of these principles. You remember what you learn first. If you learn something in a number of different ways then there is a good chance that under pressure you will revert to the one you learned first.

If you learn to dive with an agency or an instructor that teaches things one way and then switch to an agency or instructor that teaches a different technique then there is a good chance that you will feel more comfortable with the original technique and under pressure will fall back on that original technique. The interesting thing is that even if intellectually you know the second technique is better, your instincts will often prompt you to use the first technique.

Real-World Example: CPR Ratios

A real-world example of how this has an impact on me is the correct ratio of compressions to ventilations while doing CPR. Ever since 2005, the ratio of compressions to ventilation while doing adult CPR as a first aider has been 30:2. Despite doing and teaching this for 20 years I still have a momentary hesitation when I am teaching this as the previous ratio pops uninvited into my head. I know it is going to happen and I always manage to give the right ratio but I know the original ratio, the one I originally learned, is still there in my head.

Why Teaching Things Right the First Time Matters

The implications for this as training agencies and individual instructors is that it is essential we teach things right the first time. If we teach an incorrect or even just a less-than-ideal technique there is a good chance that the student will stick with that for the rest of their diving career.

This is summed up in the concept:
“It’s harder to break a habit than make a habit.”

Research has shown that habits can have a powerful influence on behaviour, often shaping our daily actions without our conscious awareness. Moreover, habits can become deeply ingrained in our neural pathways, making them difficult to modify or break. In his book, The Power of Habit, Charles Duhigg discusses the science behind habit formation and how it can impact behavioural change. This book is worth reading for any instructors that want to create positive habits in their students.

How Bad Practices Resurface in the Scuba Industry

The concept of primacy also explains why bad practices are continually creeping back into the scuba industry. We think we have eliminated a particular bad practice from the industry then, all of a sudden, we see that bad habit pop up in newly trained divers.

Where did they pick that up?

The answer is that a diver picked up that habit many years ago during their initial training. That particular diver has kept doing that habit despite the fact that most other people have stopped doing it. They progress through the ranks and eventually become an instructor themselves. Now they start teaching that same practice to their students and all of a sudden there is an outbreak of that same bad habit.

Example: The Quarter Turn Back on Tank Valves

A very common example of this is the quarter turn back when opening cylinders. Despite the fact that none of the major agencies teach this it is still very common and new instructors regularly teach it.

The articles below lay out the reason why we no longer teach it but I think it is interesting that the DAN article is titled “Old Habits Die Hard”.

🔗 Old Habits Die Hard – DAN
🔗 Tank Valve Etiquette – TDI/SDI

How Instructors Can Accidentally Reinforce Bad Habits

Instructors can inadvertently create bad habits in the way they build up teaching skills. It can be a challenge to get a diver to perform the whole of a new skill the first time and so the instructor naturally splits the skill into several parts. However, the instructor must be careful that by doing this they are not introducing errors or delays into the whole skill.

Common Teaching Pitfalls

Students removing a regulator from their mouth and giving a “look I am blowing bubbles” signal because that’s how they were taught.
Instructors telling students during a rescue course to shout “PIZZA” instead of “HELP” to avoid alarming others—only for a real-life rescue situation where a diver actually shouted “PIZZA”.

The Problem of Teaching Skills While Kneeling

Some instructors will teach mask clearing and regulator remove and replace while kneeling on the bottom. They do this for what they believe are good reasons.

However, this creates two major problems:

Conditioning Divers to Kneel Instead of Hover
- Under stress, they may instinctively try to kneel—even when there is no bottom to kneel on.
Skills Function Differently When Neutrally Buoyant
- A regulator in a kneeling position falls behind the hip.
- A regulator in a horizontal position falls in front of the chest.

If we start by teaching our students buoyancy and then move on to doing skills neutrally buoyant, we are using primacy to our advantage rather than trying to fight it.

Conclusion

I don’t care if you know how many laws of learning there are or if you remember the name or the nationality of the person who first wrote them down.

My intention in this article is to make it clear how important it is that we teach the right skills, in the right way, right from the beginning of our students’ training.

3 replies

Andrea Caronti says:
March 25, 2025 at 9:44 am

Another great contribution from Mark Powell. It is incredible how this article approaches from a 360° angle all major teaching pitfalls from many instructors!

I would like to stress out what I always said to my students: never do something just because your instructor says so! Learn from so many instructors as possible and then choose the teachings that make more sense from every of them!

As a student and diver, flexibility, adaptability and ability to think with your head are major advantages in your evolution path!
Reply
James says:
April 2, 2025 at 10:11 am

My issue is that SDI is still putting out materials recommending the quarter turn back, which as we know today can lead to incidents. This is still recommended on page 325 of the “SDI Open Water Scuba Diver Instructor Manual” still in use at least as far back as September when I took my IDC. Perhaps it is understandable that this would still be common in material published in 2009, but that begs the question – why new editions of material published every few years to reflect important new information and to remove outdated information. For instance the NOAA Diving Manual was on its 5th edition in 2013 and today that is considered old literature with the publication of the latest 6th edition published in 2017.
Reply
- Krymson-sky Elvir says:
  April 9, 2025 at 11:37 am
  
  Thank you for taking the time to bring this to our attention. You’re absolutely right to highlight the safety implications tied to the outdated “quarter turn back” practice, and we appreciate your dedication to ensuring the highest standards of diver training.
  
  We can confirm that SDI has already taken steps to address this. The recommendation for the quarter turn back has been removed from our newly released Dive Master (DM) materials, and it will also be absent in the upcoming release of the Open Water Scuba Instructor (OWSI) manual. We are actively rewriting and updating our instructional materials to reflect current best practices and eliminate legacy content that no longer aligns with today’s standards.
  
  It’s an ongoing priority for us to ensure our curriculum evolves alongside the industry and scientific understanding—much like the updates seen in resources such as the NOAA Diving Manual. While legacy content can sometimes linger in older documents still in circulation, we are committed to thoroughly reviewing and revising our materials to eliminate such discrepancies.
  
  We truly value feedback from dedicated professionals like yourself. Your insight helps us stay accountable and aligned with our core values of safety, education, and progress.
  Reply