Maybe set up something on your phone that pings you a few times each day at random times to track your mood across the day. Whenever you get a ping, write down the time, and then for example what you were doing, your subjective mood, subjective energy level and how spaced out or focused you're feeling.

Heart Rate Varience Biofeedback is a good meditation target if you want to meditate in a quantifieable way.

If you want to go a less direct way http://www.quantified-mind.com/experiment/meditation is an existing program to measure effects of meditation by Quantified Self people.

Mostly I think measuring things is besides the point of meditating, but I'm not going to stop you, only warn you that it's creating a feedback loop that encourages you to identify with meditation attainment that may eventually leave you stuck in a local maximum.

Meditation acutely improves psychomotor vigilance, and may decrease sleep need:

• https://behavioralandbrainfunctions.biomedcentral.com/articles/10.1186/1744-9081-6-47

The data (currently unpublished) I spoke of regarding the 45min mark is part of a larger ongoing effort to characterize changes that occur to the "mind" as people shift to a different way of experiencing their reality.

• http://nonsymbolic.org/publications/

In my own experience as well the 40-45 min phase change is often blurred to the point of being unnoticeable. I'm still not 100% convinced it isn't a priming effect though I think it has decent theoretical support. My simplified explanation is the brain cannot switch modes too rapidly. For example it's easy to get HR up to 180 bpm in the blink of an eye if you think a tiger is leaping at you but takes considerably longer for it to go back to normal when you realize it was just the shadow of a harmless bush).

Regarding the tally counter: what you consider mind-wandering can/should change over time. Initially only click for completely losing attention and as improvement occurs you can include more and more subtle attentional deviations. Like any other tool it has a limited range where its use is appropriate. I'm not sure it helps too much with learning meditation; its more of a very simple way to vaguely-objectively track your progress over time.

A key principle to keep in mind is that not every meditation style is right for everyone all the time. TMI is heavily focused on anapanasati but there are a multitude of other styles. You may find your mind is more "in tune" with body scanning (e.g. Goenka) or something a little more wacky like Headless Way:

• http://www.headless.org/experiments.htm

The research I linked to above found that people progressed much more rapidly if they were practicing a technique that was right for them. This is not an excuse to flail around randomly. At least one week of bona fide dedicated practice should be attempted before trying something else but months/years of painstaking effort with little gain is almost always a needless waste of time. That being said there is a fine line between the right amount of dogged persevering and dogmatic perseveration.

Big 5. Use the same test each time. Ideally you'd also have an external assessor complete a questionnaire about you (someone who interacts with you closely) and compare the 4 results.

I've used TMI as a meditation guide off and on for some time. One thing you might consider tracking is "generalized motivation", or "energy level", or something like that. You might have to measure this subjectively, by rating how motivated you feel, or you could keep track of your ability to objectively get things done. I find that too much* meditation results in an undesirable degree of affective flattening and a reduction in motivation and energy level. For these reasons, I actually don't meditate currently.

*"Too much" may vary, but I think 20 minutes per day is a low enough level to avoid the negative side effects. Of course, at 20 minutes a day, you're also not going to achieve the desirable outcomes.

Firstly, I would like to say TMI is a great book and the "interludes" match up well with my subjective experience.

Secondly, the concerns moridinamael mentions are typically not an issue for beginning meditators. Motivation issues usually don't manifest until one has accumulated a number of "insights" which often requires hundreds or thousands of hours meditating. Flat affect can be mitigated by interleaving metta style meditation into the follow-breath-at-nose routine. Anecdotally from some meditation lineages - and from examining self report data from roughly 200 meditation practitioners - there seems to be a bump in meditation quality that happens after 40 to 45 minutes of sitting on the cushion so I would recommend you aim for 1 hour/day.

As justinpombrio said (for certain types of focused meditation training) attentional blink was shown to decrease:

• https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.0050138

Another task is the psychomotor vigilance (PVT) task which has a long history in sleep deprivation research:

• https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.0050138

A simple technique to "objectively" measure focused attention style meditation progress is to use a hand tally counter. During a meditation session whenever you catch yourself mind wandering you simple click the counter. At first remembering to click is hard but after a week or two of daily practice it becomes second nature. For me after a while it became so second nature that I would sometimes have enough awareness to click to register the mind wandering but not enough awareness to actually return to the breath. An upgrade would be to hook up to some sort of arduino and timestamp each click looking for trends (e.g. does your mind quiet down earlier in a session as your cumulative practice time increases).

A step up is to track physiological data (e.g. heart rate variability) and EEG (e.g. using the MUSE)

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5838011/

OTOH it is likely you will experience changes to well-being before anything more quantifiable shows up:

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5464416/

This sounds cool, and I am interested in what you discover.

A problem I can see with doing this as a single-person experiment is that tests like Dual N-Back also function to improve your attention and working memory as you practice them, so improvement over time would be expected whether you were meditating or not.

It's seems difficult in a first place to measure... But why not. Validity and sensitivity won't be that big of a problem if you decide to use standardized tests. I'm more concern about fidelity.

It will most likely contain some error. Your test can give you some result that you might interpret when in reality it can only show random fluctuation. Understand here : There are standardized tests, so they won't show you random fluctuations but they're designed to measure a criteria IN GENERAL and not the part of this measure which is due to your meditation. Here there is kind of a blurring between sensitivity and fidelity...

Fidelity : I'm concern about consistency, there is so much things that can interfere with this especially when you're trying to measure stress (Stroop), attention and time reaction : tiredness, motivation etc.. And each of these factors are altered by your meditation routine ! It's kind of a mess. (Maybe Alpha Cronbach ?)

You would need a large amount of try to get some usable data out of it. You would also need to control general tiredness and motivation, who can have a large impact on your result (would be the first thing i'd measure in fact)... Well it seems difficult and I won't be the person who's going to stat this up !

I suggest you use standardized test used for meditation if it exists in pseudo clean condition (the cleaner you can)

Good luck