klibertp,

> another thought on the study: does it control for presence or absence of widely known conventions?

I am very happy to encounter other critical thinkers - your question is a really good one :) You are right, the study is not capable of explaining this effect (that is, how commonplace / conventional some abbreviations are), but it was considered in the design. I am sure that this plays an effect but I wouldn't dare to give a definitive answer based on the data from my study.

For example, config or cfg are arguably so common that there they don't hurt comprehension. Similar for single letter variables. Point.x and point.y are easily identifyable as coordinates. Or the variable name i in a for loop may not be problematic, as it becomes almost meta-syntactic (much like foo and bar). However, i,j,k,l index names may really hurt comprehension, when you have a complicated looping strucutre with many lines in between, as they are likely to strain your working memory. As for the point.x example: I would explain this as a priming effect. The name of x is fine, because point already preactivates the right direction. X in isolation might be worse, and if you encounter new MessageBrokerInstance().X() you might as well read your code in base64... Thus, based on my experiment, I can talk about variables in isolation, but usually, code is mixed and here, other effects might be relevant.

In the longer versions of my experiment, I considered the effect of common abbreviations as well. Psychology lists several word frequency effects. Common words can be immediately accessed *(from the so called mental lexicon, a mind-dictionary if you will), but uncommon words have to be synthesized on the fly though their phonetics (see, for example the dual route cascade model, coltheart 2001, http://www.cogsci.mq.edu.au/~ssaunder/files/DRC-PsychReview2...). Thus, high-frequency words (=often occuring, common words or strings) are quickly read and their meaning is understood, whereas uncommon words or strings do not have a representation in the mental lexicon and you have to synthesize their meaning first, thus slowing down comprehension.

My argument is simple: It is always possible to understand code, no matter how mangeled or obfuscated it is (after all, reverse engineers are doing amazingly hard work). The question is how easyly the code can be comprehended. Abbreviations that are common to some (e.g. experts), may not be common to others (e.g. novices in their first job). Of course, the newbies will get there eventually, but abbreviations have a higher learning curve, thus new people will be unproductive for a longer time.

Think about yourself, you surely know this effect:

1. Write code.
2. Problem solved
3. don't touch it for 4 months
4. Changes needed, need to fix bug, add feature
5. How does this work?
6. Wtf, what was I thinking?

For the sake of all newbies, your company, or even your own, I encourage the use of identifiers that can be read, because you can READ and know LANGUAGE, and not because of arbitrary conventions. There are many conventions (e.g. x:xs, for i=0;i<10;i++, point.x) that can surely be considered domain language and don't impede comprehension, but still might hinder comprehension for novices, or yourself in 4 months.

> how relevant/applicable you think the studies you linked to are in the general case?

This is really hard to say. Many processes take place when programming, and many programmers have theories about why it is hard and how to make it easier (as the entry article citing cognitive load, which is a good methaphor, imho). So far, I know of many such scientists who are trying to isolate the different effects. For example, I am focused on identifier names, as I find them to be impactful. Their meaning can't be analyzed automatically (even with sound nlp techniques which are relatively limited), and the programmer is totally free to name their variable names what ever the hell they want. I am sure that in comprehension of programs, identifier names play a big role, but when I encounter "clever code", with weird recursions, counterintuitive measures, or plain magic (https://en.wikipedia.org/wiki/Fast_inverse_square_root) the value of identifiers are limited, or, in other words, there are other things going on that impact my comprehension BESIDES identifiers. How they interact, I cannot say for sure, but if complex code has no clear identifiers, it becomes complicated.

I believe that each of the effects in isolation is relevant, but I am not sure which one is the most dominant, or, for that matter, whether there is ONE thing that will solve all problems.