I am doing some research on the topic of learnability within usability. I am currently struggling to find out who was the first one to use it in this context?
Any help would be really appreciated.
The earliest reference I could find was from the seminal 1983 book "The psychology of human-computer interaction" by Stuart K. Card, Thomas P. Moran and Allen Newell.
"Designing to improve performance on one dimension does not necessarily help performance on other dimensions. For example, optimizing the performance time of a system does not improve its learnability..."
I don't have a copy of the full text, but perhaps your library does.
I know its referenced in ISO/IEC 9126. As far as who introduced it, I believe it was Jacob Nielsen. I was unable to find a concrete source, but several secondary sources reference him when discussing the topic. It could have also been Professor Ben Shneiderman:
The first use of learnability describes the ability of an interface to allow users to accomplish tasks on the first attempt.
We often refer to this as usability for first time use. Nielsen also defines learnability as easy first time use but lists learnability as a sub component of the construct of usability.
The second definition is described as:
... learnability is usability over time. Basically, task performance, which is also measured using the classic usability metrics, improves after repeated "trials." More practice results in less time needed to complete tasks. Typically, the improvement isn't linear, but logarithmic.
ISO 9126 also references "learnability", via Wikipedia:
In software testing learnability, according to ISO/IEC 9126, is the capability of a software product to enable the user to learn how to use it. Learnability may be considered as an aspect of usability, and is of major concern in the design of complex software applications.
This seems to fall more in line with the second definition from the Measuring Usability article.
For how and who it was first introduced into the lexicon, you will need to pick which definition you want to use (also, there may be other definitions that I didn't find).
In the case of the first definition, you'd probably be safe to assume Nielsen introduced it himself. That's an assumption though; he doesn't site where he may have heard it before though.
In the case of the second definition, it falls back to the basic definition of "learn". From The Free Dictionary definition:
v. learned also learnt (lûrnt), learn·ing, learns
- To gain knowledge, comprehension, or mastery of through experience or study.
... so when did "learn" first enter the language. If we go down this path, Online Etymology gives us a few clues. It only mentions the origins of "learn" back to old English (i.e., really long ago), but does list the appearance of "learnable" as somewhere in the 1620's:
learnable (adj.) Look up learnable at Dictionary.com
1620s, from learn + -able.
But as to who first uttered the word "learnability" while speaking about usability, I am unaware. I'd argue it is simply a natural use of the word in the context of a practice in the case of the second definition.
In my research I have found a reference to Learnabity from 1976. It apperaed in the following article:
J. C. R. Licklider. 1976. User-oriented interactive computer graphics. In Proceedings of the ACM/SIGGRAPH Workshop on User-oriented Design of Interactive Graphics Systems (UODIGS '76). ACM, New York, NY, USA, 89-96. DOI=10.1145/1024273.1024284 http://doi.acm.org/10.1145/1024273.1024284
Because graphics opens wide new horizons to designers and users of interactive graphic systems, interactive graphics systems tend to be both novel and complex. Typically, the user has to do a lot of learning in order to become pro- ficient."
The article "A Survey of Software Learnability: Metrics, Methodologies and Guidelines" by Tovi Grossman also suggests that this might be the oldest reference to learnability within HCI.