Just over a year ago the Ergonomics Society changed its name to the Institute of Ergonomics and Human Factors, in recognition (among other things) of the discrepancy between the growing range of interests within the organisation and the somewhat narrower perception of the term “ergonomics” to the world outside. There are many people who feel passionately about such terminology, and will argue quite strongly that it is perceptions that we should be changing, rather than our own identity. On the other hand, there are those who think that it is quite right that organisations should evolve to reflect the changing world, and that names and labels should not be thought of as sacrosanct.
But the purpose of this post is not to enter that debate. Instead, it is to test some of the assumptions about the usage of these terms, and see if they really hold true. This task is made somewhat easier by the recent launch of the Google Books Ngram Viewer, which gives us a unique insight into the usage of terminology across a range of publications, time periods and corpora (i.e. geographically-based collections). Google Books claims to have scanned over 10% of all books ever published, providing data on the occurrence of phrases up to five words in length from 1400 through to the present day.
For example, I had assumed (wrongly, as it turns out) that the term ergonomics was more prevalent this side of the Atlantic, and conversely that human factors was the dominant term on the other. This is a crucial point, as it underpinned the notion (in my mind, at least) that by adopting the term human factors we would better articulate our identity and mission to a global audience. (Indeed, by changing the name that outcome may still hold true, but evidently not for the reasons I’d assumed.)
So let’s look at the data. First, let’s see how often the terms “ergonomics”, “human factors” and “user experience” appear in all the English books indexed by Google, from 1950 to date. I have included the third term partially as it reflects my own personal interests (being by far the dominant term in the development of digital interactive products, e.g. web, software, mobile, and so on), and partially as a reflection of its growing acceptance in wider UCD circles (such as official standards documentation).
As I expected, user experience took off in the late 1990’s and continues on an upward trend. But what I didn’t anticipate is that ergonomics continues on an upward trend too, whilst usage of the term human factors actually appears to be declining from about 1990 onwards. This was certainly unexpected. So let’s check whether a geographic effect is at play: is this true of books published on both sides of the Atlantic? If we look at just those published in GB, then we see that user experience continues to rise, as expected, but both ergonomics and human factors start to fall from around 2000 onwards (with ergonomics entering a particularly steep decline):
Conversely, if we look at just books published in the US, then all 3 show a strong upward trend, and contrary to my own expectations, ergonomics is actually the dominant term over the last decade and a half:
The contrast between the US & GB trends is puzzling – why are ergonomics and human factors in such steep decline in GB when they are rising in the US? There must be further factors at play. Unfortunately, Google Books does not allow us to formulate queries such as “show me occurrences of these terms in all corpora except this one” (i.e. to see what the global trend is outside of either US or GB). Note also that the y-axis shows only percentages, so it is not possible to establish a baseline by which we can compare the absolute figures for different corpora.
So let’s try a different analysis. If Google Books represents the “supply” side, i.e. content creation, what is the corresponding picture from the “demand” side, i.e. the content consumption? For this we can use Google Trends, which allows us to see how often certain topics have been searched for on Google over time (and also how frequently these topics have appeared in Google News stories). Applying the same query to Google Trends produces the following result, with the y-axis showing the average worldwide traffic for all three terms normalised by the dominant term (ergonomics), and the x-axis showing the time period for which data is available:
Evidently, ergonomics is still the dominant term, but both this and human factors are in decline throughout the time period (note also the seasonal spikes at the end of each calendar year). User experience appears stable and dominates the Google News content, but it is hard to conclude more without being able to magnify the scale or probe further.
As a final datum, we should of course consider how frequently the various terms appear in the Google index itself (i.e. across the Internet). Would the patterns from Google Books be reflected across the web in general? Querying Google with each term in turn returns the following results:
- Ergonomics 6,110,000 results
- “Human factors” 2,350,000 results
- “User experience” 14,900,000 results
So, what can we conclude from all this? My personal feeling is that these investigations present many more questions than answers at this stage, so any conclusions we can draw thus far should be tentative at best. That said, the data would appear to suggest the following:
- The assumption that human factors is the dominant term in the US no longer appears to be true (at least, not for the last decade and a half)
- Usage of human factors appears to be declining globally, while both ergonomics and user experience continue to rise
- Both ergonomics and human factors have risen in the US over the last decade, but fallen in GB
- From a “demand” perspective, both ergonomics and human factors appear to have steadily declined over the time period for which data is available
- User experience is by far the dominant term across the Internet in general
Over the next few days I’ll be thinking about further ways to explore or validate the above observations. In the meantime, if you want to suggest any extensions or observations of your own, just drop me a line either here by email.
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Human Factors and Ergonomics are both well defined disciplines both academically and vocationally. I’m not sure “user experience” is well defined and if there is agreement upon the discipline, lending for overuse and possibly misuse.
Tim: Thanks for stopping by. I agree that UX is a newer term so inevitably there will be more latitude over its usage (both intentionally and otherwise). But definitions do exist and are converging within the community, notably:
http://uxmatters.com/glossary/
I think the fact that ISO have adopted it is also a significant milestone. But let’s see what the evidence says – I hope to investigate patterns of usage (including your assertion that Erg & HF are both well defined) in a follow up post.
Interesting insight!
I think the self explanatory nature of the term “user experience” may have an impact on its increasing popularity compared to erg & HF.
A certain amount of prior knowledge about the discipline is required to fully understand the terms “ergonomics” and especially “human factors”, whereas “user experience” does exactly what it says on the tin! This could have an influence on news reference due to the unknown prior knowledge of the readers.
It’ll be interesting to see the context in which these terms are used, with “ergonomic” and “user experience” possibly used more in areas such as marketing (although maybe not always correctly!).
Tony
Interesting. I get Google Alerts each day on both ergonomics and human factors. The content of what is appearing on Google each day related to these terms would suggest to the me that the term ergonomics is growing because of its strong relationship with the world of office products, furniture, consumer products, etc. I feel that this area has totally hijacked the word and therefore increased its prevelance.
Perhaps now the Human Factors term is left as something closer to that which the professionals in this area would use in terms of the integration of the physical and cognitive etc – what we used to call ergonomics!
David: I think you make a good point here. I have often wondered why we have a discrete “Cognitive Ergonomics” conference and community, but there seems to be no “Physical Ergonomics” equivalent (presumably because the base term alone has evolved to subsume this sense by default?)
I have a doctorate in ergonomics from the UK but have worked for 30 years in Canada (arguably a mid-Atlantic country from its use of English, spelling and use of certain terms). I have always been challenged by the uses of the terms human factors and ergonomics so the term user experience only adds to the definition problems. Human factors can be used for the field, of study or application OR for the things we work on, user factors (such as anthropometrics, fatigue, knowledge) environmental factors (such as light levels, cold, humidity), work situation (time pressures, complexity, boredom) and equipment factors (such as display size, control resistance).
Ergonomics has often been used to refer to the physical factors, and especially office workstation design but Europeans usually us the term more broadly, including cognitive issues, displays and controls, for example. Without knowing the contents of these publications I cannot understand the possible reasons for the trends in use rates. I ust need an elevator speech (of 20 seconds) to explain what I do to others at parties.
Thanks for a really interesting post. In my view user-experience encompasses both ergonomics and human factors – ux design should harness the same user-centred and scientific approaches that are central to ergonomics and HF, but also includes the aspects of design and development that make interaction with a device fun.
However… in my experience the term ux is often used by web designers and developers rather than industry specialists / academics. I think I agree with Tim M that human factors and ergonomics are well defined terms with recognised industrial and academic meanings; one would typically expect a human factors or ergonomics practitioner to be a highly qualified and experienced professional, whose specialism is rooted in science, whereas a “ux middleweight” might simply be a web designer with a fondness for buzzwords.
I suspect that the term is being perpetuated by the growing number of self-styled technocrats who attend endless unconferences, blog constantly about the latest development in collaborative hub love and think the Nielson Norman Group is a band their parents listened to in the 70s.
Of course, I could be mistaken :-).
Hi Tony, enjoyed this article in The Ergonomist this month.
I worked with Xerox in the late 70’s early 80’s in the department called ID/HF (Industrial Design & Human Factors). In about 1983 the HF department in the UK spawned the IU Group consisting of one industrial designer, myself, who also produced the on screen graphics, (we did our testing with a BBC Micro, see my website for some pictures) and 3 or 4 HF engineers. Interestingly they were termed ‘engineers’. The whole HF team plus the UI Team was lead by Richard Blyth who until a couple of years ago headed the Human Factors team at BT Labs.
Your article just made me wonder when the terms User Interface and User Interaction came into being. They tended to evolve as we changed from a control panel (Man Machine Interface) to an interactive visual display, in those days a CRT.
Thanks for the good read
Ron
Hi Ron
Thanks for stopping by. Did you catch the follow up post (Changing terms for changing times: Usability, HCI, UCD & more)? It discusses a few of the terms you mention, and looks at some of the wider issues around that.
FWIW I tried the terms you suggest here: http://ngrams.googlelabs.com/graph?content=user+interface%2Cman+machine+interface&year_start=1950&year_end=2008&corpus=0&smoothing=3
MMI is clearly a non-starter (mainly due to the inherent sexism and ‘noise’ issues I suspect). The drop off in UI is intriguing tho … I suspect the focus over the last decade has widened to look at the user experience more holisticallly with the UI considered as just one element of that (and hence no longer the primary focus of research and scholarly publication).
[…] interesting data-based review of the changing terms over time see Tony Russell-Rose’s blog post here.) It can be argued that these terms refer to similar yet different aspects or perspectives of the […]
I’m currently a second-year MS student an Engineering Psychology program, and read this article with interest.
I’m starting to look ahead towards the job market, and have been wondering about the connotations of the terms HF and UX. Your article is among the most recent to discuss this distinction (and not many do, at all).
As an experienced professional in the field, what do you think each term connotes?
I’m interested in research-based work, as it’s applicable to higher-risk domains, like healthcare, defense and transportation.
My sense is that Human Factors connotes jobs that require human factors psychology and engineering degrees, in those domains, while UX connotes jobs that are concerned more with online and mobile user interfaces, and the design of tech products.
But when I look up jobs, I definitely see many more jobs for UX, and there is definitely more non-academic writing and advice on UX careers.
And maybe UX has overtaken the term HF, so that human factors is becoming obsolete. Do you think the fields are in fact distinct? If so, what skill sets are unique to each?
Should I be positioning myself towards one or the other, or do people tend to go back and forth?
If you have the time, I’d be very interested in your thoughts.
@Limor I think we all have different interpretations for these terms based on our subjective experience (which, without being too meta, is a typical UX reponse 🙂
That’s not to say that terms can’t be legally defined – e.g. you can only call your self a ‘doctor’ if certain provable conditions are met – but even then it means things in differen countries (e.g. in US they’d be called a physician).
So arguing about labels is ultimately a bit pointless, and trying to ‘own’ them to the extent that you can tell someone else how they should be used is even more so.
For me, HF = systems & safety critical workplaces, structured approaches etc.
UX = digital, mixed use (consumer + workplace), holistic approaches
But your mileage may vary! Language is constantly changing anyway, both on a lexical and structural level, and today’s connotations won’t be the same as tomorrow’s.
I get Google News alerts on “human factors,” and sometimes the phrase pulls in stories not related to the field as far as I can tell, as I’m not in the field but am monitoring HF/E news on behalf of the Human Factors and Ergonomics Society. Did you try to filter those types of alerts out of your data?
@Lois what we see above is the simple string searching that is supported by the 2 APIs (Google ngram viewer and Google Trends). So I think the quick answer to your question is no, we didn’t do any advanced filtering that could differentiate between the various senses of a phrase (e.g. human factors as in ergonomics vs, human factors as in the generic/colloquial expression).
What tool are you using to monitor these instances, just Google News or anything in addition?