The Shape of Code

What is the connection between a software developer’s risk attitude and the faults they insert in code they write or fail to detect in code they review? This is a very complicated question and in an experiment performed at the 2011 ACCU conference I investigated one particular instance; the connection between risk attitude and recall of previously seen information.

The experiment consisted of a series of problems having the same format (the identifiers used varied between problems). Each problem involved remembering information on four assignment statements of the form:

p = 6 ;
b = 4 ;
r = 9 ;
k = 8 ;

performing some other unrelated task for a short time (hopefully long enough for them to forget some of the information they had previously seen) and then having to recognize the variables they had previously seen within a list containing five identifiers and recall the numeric value assigned to each variable.

When reading code developers have the option of referring back to previously read code and this option was provided to subject. Next to each identifier listed in the recall part of the problem was space to write the numeric value previously seen and a “would refer back” box. Subjects were told to tick the “would refer back” box if, in real life” they would refer back to the previously seen assignment statements rather than rely on their memory.

As originally conceived this experimental format is investigating the impact of human short term memory on recall of previously seen code. Every time I ran this kind of experiment there was a small number of subjects who gave a much higher percentage of “would refer back” answers than the other subjects. One explanation was that these subjects had a smaller short term memory capacity than other subjects (STM capacity does vary between people), another explanation is that these subjects are much more risk averse than the other subjects.

The 2011 ACCU experiment was designed to test the hypothesis that there was a correlation between a subject’s risk attitude and the percentage of “would refer back” answers they gave. The Domain-Specific Risk-Taking (DOSPERT) questionnaire was used to measure subject’s risk attitude. This questionnaire and the experimental findings behind it have been published and are freely available for others to use. DOSPERT measures risk attitude in six domains: social, recreation, gambling, investing health and ethical.

The following scatter plot shows each (of 30) subject’s risk attitude in the six domains (x-axis) plotted against percentage of “would refer back” answers (y-axis).

A Spearman rank correlation test confirms what is visibly apparent, there is no correlation between the two quantities. Scatter plots using percentage of correct answers and total number of questions answers show a similar lack of correlation.

The results suggest that risk attitude (at least as measured by DOSPERT) is not a measurable factor in subject recall performance. Perhaps the subjects that originally caught my attention (there were three in 2011) really do have a smaller STM capacity compared to other subjects. The organization of the experiment (one hour during a one lunchtime of the conference) does not allow for a more extensive testing of subject cognitive characteristics.