PERSONAL PSYCHOLOGICAL SCIENCE:
A PRACTICAL INTRODUCTION

When I tell people I’m a psychologist, they often assume I’m a clinical psychologist. They think I spend my time listening to people’s mental health problems and helping them overcome them.

But that’s not what I do. I’m a researcher who studies human behaviour from a scientific perspective.

When I explain that I run experiments, teach statistics, or study things such as social status and how people learn from others, people often seem surprised. It’s as if there is a disconnect between psychology as a science and psychology as a way of helping people in their everyday lives.

Of course, psychological research already informs many practical psychological interventions, from mental health treatment to education and public policy. But I think psychological science could be useful in another way: we could use it ourselves to investigate our own lives.

This is the idea behind what I call personal psychological science.

Personal psychological science

The basic principle of personal psychological science is simple. Rather than relying exclusively on general advice about how to live better, we can use psychological knowledge and scientific methods to learn about ourselves and discover what works for us.

After all, psychological research often aims to understand how people behave in general. But people also differ in important ways. Our personalities, experiences, circumstances, and goals are not the same. What works well for one person may not work equally well for another.

Personal psychological science takes these differences seriously. It involves learning from existing research, critically evaluating advice, observing our own behaviour, and sometimes conducting simple personal studies to test ideas in our everyday lives.

The aim is not to replace psychological research with personal experience, but to draw on different sources of evidence. General research can tell us what tends to happen across groups of people and under particular circumstances, while personal investigation can help us explore what happens in our own particular circumstances.

In this way, we can become more than consumers of psychological knowledge. We can become active investigators of our own behaviour, using science to make better-informed decisions about our lives.

Different questions require different sources of evidence. Sometimes the best starting point is psychological research. Sometimes it’s your own history. Sometimes it’s other people’s experiences. Often, it’s a combination.

Let’s look at how this might work in practice through three examples:

1. Does expressing gratitude make me happier?
2. How can I make new friends?
3. What is damaging my sleep?

Example 1: Does expressing gratitude make you happier?

I would like you to try the following three-step exercise.

Step 1: How do you feel right now?

Answer the following questions using a scale from 1 (not at all) to 7 (very much).

1.- Right now, how positive do you feel? _____

2.- Right now, how grateful do you feel? _____

3.- Right now, how connected do you feel to other people? _____

4.- Right now, how meaningful does your life feel? _____

5.- Right now, how optimistic do you feel about the future? _____

Step 2: Express gratitude

Think of someone who has positively influenced your life. Write a short note on a piece of paper describing what they did and why it mattered to you.

Step 3: Measure again

Now answer the same questions again, using the same scale from 1 (not at all) to 7 (very much).

1.- Right now, how positive do you feel? _____

2.- Right now, how grateful do you feel? _____

3.- Right now, how connected do you feel to other people? _____

4.- Right now, how meaningful does your life feel? _____

5.- Right now, how optimistic do you feel about the future? _____

What happened?

Now it’s time to look at your results.

A good place to start is with the big picture. Calculate your average score at the two time points. To do this, add your five answers and divide the total by five.

What happened? Did your average score go up, go down, or remain roughly the same?

Next, look at the individual measures. Some scores may have gone up, others down, and some may have stayed the same. What happened in your case?

Once you have looked at the numbers, it’s time to think about possible explanations. Why do you think your results changed—or didn’t change?

Importantly, this simple exercise cannot tell you with certainty that writing the gratitude note caused any changes you observed. Your feelings could have changed for many reasons. But it gives you an observation and, perhaps, a hypothesis worth investigating further.

And if your scores did not improve, that’s interesting too. Psychological interventions do not necessarily work for everybody, all the time, or in every situation.

For example, I have always found that being in contact with nature—such as sitting and contemplating the sea—improves my well-being. However, during the COVID-19 pandemic, I sometimes found it impossible to relax by doing exactly that. At the time, I was extremely stressed because I had lacked direct contact with close friends and family for several months.

The same activity can therefore have different effects depending on what else is happening in our lives.

Practical tip: If you found—or think—that the gratitude exercise was useful for you, at least in some situations, you might add it to your toolkit of strategies for improving your well-being. Then you can investigate the conditions under which it works best for you. Does it help when you’re in a low mood? Does doing it in the morning affect how you feel during the day?

Example 2: How can I make new friends?

Personal psychological science does not necessarily mean running self-experiments. Sometimes an experiment isn’t the best way to tackle a particular personal question.

Imagine that you have been struggling to make new friends for a while. You might ask yourself: What can I do to make new friends?

A good place to start is by looking at how you made friends in the past. You could look back over your own life and ask questions such as:

• Where did I meet my current and previous friends?

• How often did we initially see one another?

• What were we doing?

• What did we have in common?

• Who initiated contact?

• What happened between being acquaintances and becoming friends?

If I look at my own personal history, for example, many of the friends I had during adolescence attended the same school. I saw—or could potentially see—them very frequently, perhaps five days a week. We shared common interests, such as similar tastes in music, and we met through structured activities such as classes or through mutual friends and acquaintances.

Looking at this example, several conditions stand out: proximity, regular contact, shared interests, and structured activities.

My personal case study tells me something about the conditions under which friendships have developed for me in the past. Of course, I’m not a teenager anymore, and I can’t simply recreate the circumstances of my adolescence. But I can gather another kind of information.

For example, I could ask other people who have recently made a close friend the same kinds of questions that I asked myself about my previous friendships. Ideally, I would ask people whose circumstances are similar to mine in relevant ways—for example, people with a similar relationship status, similar age, or who live in the same city—because their experiences may be more directly relevant to my situation.

Once I have both types of information, I can look for patterns across my own experience and the experiences of other people, while also considering my current circumstances and interests.

For example, one woman told me she made friends through photography classes, while one man made friends by regularly playing football with the same group of people. Although these activities are quite different, they share several features: a structured activity + repeated contact with the same group of people + a shared interest. Importantly, they also recreate, to some extent, the conditions in which I made friends in the past.

So, if I enjoy photography or football, these might be promising ways to meet people while doing something I already like.

But if I’m not particularly interested in photography or football, simply copying what these people did would make little sense. Instead, I can look at the underlying pattern and ask how I could recreate similar conditions around something I’m interested in.

In my case, I’m passionate about music. I could join a band or attend regular dance classes. The specific activity changes, but some of the potentially important conditions remain: a shared interest, repeated contact, and opportunities to interact with the same people over time.

Of course, this doesn’t guarantee that I’ll make new close friends. But I now have a hypothesis based on evidence from my own life and the experiences of other people—and, importantly, something concrete I can try.

There is also no rule saying that these two methods—looking at your past experience and asking other people—must always be combined. Which sources of information are useful depends on the question.

For example, imagine that you’re choosing a university for the first time. You don’t have previous personal experience of choosing and attending a university to examine. In that situation, it may make more sense to learn from people who do have relevant experience.

But you still shouldn’t simply copy what worked for them. You can first identify what matters to you in a university—perhaps the quality of a particular programme, opportunities to meet people, cost, location, or teaching style—and then evaluate other people’s experiences in relation to those priorities.

This illustrates a broader principle of personal psychological science: don’t just ask what worked for someone else. Ask how relevant their experience is to you.

Practical tip: You might initially think that you don’t have enough people to ask these kinds of questions. The conversations don’t need to be formal interviews. You can bring up these topics naturally in social situations. I’ve talked about them with people at Meetup events and with people I meet for language exchanges. I’ve even asked people I didn’t previously know questions about my interests through Facebook, email, or LinkedIn.

Example 3: What is damaging my sleep?

Imagine that you haven’t been sleeping particularly well. You often struggle to fall asleep and sometimes wake up feeling that you haven’t rested enough. What could be causing it?

You search online and find all kinds of advice: avoid caffeine late in the day, stop looking at screens before bed, exercise more, keep your bedroom cool, go to bed at the same time every night, and so on.

The problem is that changing everything at once won’t tell you which changes actually matter for you.

In this situation, it may be better to try different pieces of advice and test them separately. In this example, we’ll look at caffeine and screen use.

Research indicates that caffeine can interfere with subsequent sleep, and its effects depend partly on how much caffeine we consume and how close to bedtime we consume it. One meta-analysis estimated that a typical cup of coffee should be consumed around nine hours before bedtime to avoid reductions in total sleep time.

Research and public-health recommendations also provide reasons to reduce screen and electronic-device use before bedtime, although there is less certainty about exactly how long before bed people should stop using them.

So now we have two scientifically plausible things to try. The question is: which, if either, matters for us personally?

Phase	What you do
A: Baseline	Normal routine for 7 days
B: Caffeine restriction	No caffeine ~9 hours before bed for 7 days
A: Return to baseline	Normal caffeine habits for 7 days
C: Screen restriction	No screens for 1 hour before bed for 7 days

Step 1: Establish your normal sleep

The first thing you will need is to establish a baseline: an idea of what your sleep normally looks like before you deliberately change anything.

To do this, you should not deliberately change anything for several nights—for example, seven days. During this time, continue your normal routine and, every morning, record your sleep quality by answering this question:

How well did I sleep last night?

Very badly 1 — 2 — 3 — 4 — 5 — 6 — 7 Very well

You could track additional measures, such as hours of sleep, perhaps using a sleep tracker. But to keep this example simple, we’ll just rate sleep quality.

Step 2: Change one thing

If you think caffeine might be contributing to your poor sleep, it makes sense to start there. For the next seven days, stop consuming caffeine around nine hours before your usual bedtime. During this time, keep recording your sleep quality.

At the end of the period, calculate your average sleep quality for each week. Simply add your seven ratings and divide the total by seven. You can then compare your average sleep quality during your normal routine with your average during the caffeine-restriction period.

Has your average sleep quality changed? If your average sleep-quality score increased, this provides some initial evidence that restricting caffeine may have improved your sleep.

If your sleep quality stayed roughly the same, that’s useful information too. So far, you haven’t found evidence that this particular change in your caffeine consumption improves your sleep.

Either way, we shouldn’t draw a strong conclusion from a single comparison. Something else could have changed between the two weeks.

Step 3: Return to your normal routine

Next, return to your normal caffeine habits for another seven days while continuing to record your sleep.

Why go backwards? Imagine that your average sleep quality was 4.0 during your normal routine and increased to 5.2 when you restricted caffeine.

That’s interesting, but the improvement may have had nothing to do with caffeine. Maybe the second week was simply less stressful.

Now imagine that when you return to your normal caffeine habits, your average sleep quality falls to 4.1.

The pattern is becoming more interesting:

• Normal caffeine → 4.0

• Restricted caffeine → 5.2

• Normal caffeine → 4.1

Your sleep improved when you changed your caffeine consumption and worsened when you changed it back.

This still doesn’t prove that caffeine caused the difference. Other things could have changed at the same time. But the pattern gives us more reason to suspect that caffeine might be contributing to your poor sleep.

Step 4: Try something else

Now you could test another recommendation.

For example, return to your usual caffeine intake but avoid screens—such as your phone, tablet, computer, or television—for a set period before bed. You might decide to test one hour without screens before bedtime for seven days.

The one-hour period is simply the condition we have chosen to test. Don’t interpret it as a scientifically established cutoff that works for everyone.

During this period, continue recording your sleep quality every morning.

At the end of the seven days, calculate your average again and compare the different periods. Did your sleep seem to improve during the caffeine restriction? During the screen restriction? During both? Or during neither?

You have now moved beyond simply asking, What does the research say I should do to sleep better? Instead, you have started with scientifically plausible recommendations and gathered evidence about how they appear to work for you.

Whatever the result, you now have information that can guide your next step. You might decide to keep using a practice that appears to work well for you. Or, if neither intervention seems helpful, you could use the same approach to investigate other possible influences on your sleep.

Practical tip: If you want greater confidence in your findings, repeat a condition that appeared to work. For example, if restricting caffeine was followed by better sleep, you could introduce another seven-day period in which you restrict caffeine again. If your sleep improves again, you now have the same pattern occurring twice. Repeatedly seeing your sleep improve when you introduce a change—and worsen when you remove it—provides stronger evidence than observing the change only once.

Conclusion: Living with Curiosity

In this article, I’ve introduced what I call personal psychological science: a way for individuals to generate knowledge about themselves and discover what works for them by asking questions, gathering evidence, looking for patterns, considering alternative explanations, and testing ideas.

The point of personal psychological science is not to turn everyday life into a permanent laboratory in which everything must be measured. It’s a tool we can use when we need it.

For example, we can use it when we want to find ways to improve our well-being and connection with others (Example 1), identify circumstances that may favour the development of close friendships (Example 2), or investigate a recurring problem such as poor sleep (Example 3).

Perhaps most importantly, personal psychological science encourages us to approach our lives with curiosity. Instead of searching for a magic formula that will tell us how to get what we want, we can use advice, findings from psychological research, and our own experiences to generate hypotheses about what might work for us—and then investigate them.

If you’d like to learn more about personal psychological science and how you can use it in your own life, subscribe to my newsletter. You’ll get new articles, practical tools, tutorials, live talks, and other resources by email.

References

Centers for Disease Control and Prevention. (n.d.). About sleep. https://www.cdc.gov/sleep/about

Dang, A. V., Coles, N. A., Oishi, S., & McCullough, M. E. (2026). The efficacy of seven gratitude interventions for promoting subjective wellbeing. The Journal of Positive Psychology, 21(3), 517–535. https://doi.org/10.1080/17439760.2025.2502483

Gardiner, C., Weakley, J., Burke, L. M., Roach, G. D., Sargent, C., Maniar, N., Townshend, A., & Halson, S. L. (2023). The effect of caffeine on subsequent sleep: A systematic review and meta-analysis. Sleep Medicine Reviews, 69, 101764. https://doi.org/10.1016/j.smrv.2023.101764

Shechter, A., Quispe, K. A., Mizhquiri Barbecho, J. S., Slater, C., & Falzon, L. (2020). Interventions to reduce short-wavelength (“blue”) light exposure at night and their effects on sleep: A systematic review and meta-analysis. Sleep Advances, 1(1), zpaa002. https://doi.org/10.1093/sleepadvances/zpaa002