Re: [SystemSafety] Fwd: Re: power plant user interfaces

From: Smith, Brian E. (ARC-TH) < >
Date: Wed, 15 Jul 2015 16:51:05 +0000

Very much agree, Steve, it¡¯s not possible to find a metaphor for every system.

The point I was trying make is that in, say the flight deck of an airplane, certain things like how the horizon moves in an ADI and how the landing gear lever is designed (some with little wheels on the end to remind pilots what system the lever controls without having to look) and how it moves positionally - up or down - serve as an intuitive HMI metaphors for the real world outside or the associated airborne system.

See: Why the wheel on landing gear levers?

I would argue that arrows and altitude/airspeed speed tapes on cockpit PFDs are possibly at the same level as the landing-gear lever design.

Metaphors can exist at multiple levels. At each level, they should as you say, create a situation where people don't even realize a difference.

Clear as mud?


>The whole point of a metaphor is to take something that the person is
>already familiar with--like how a railroad switching yard works--and use
>that to help them understand something they don't know about--like how a
>network router works. In fact, network routers and railroad switching
>yards are entire different under the covers, but it's much easier for the
>person to understand routers in terms of switching yards.
>Effective HMI metaphors would be unlikely to be at the level of arrows,
>needles, etc. The metaphor should be at a much higher level.'s
>"shopping cart" metaphor is a perfect example of proper use of a metaphor
>in UI. There's no such thing as a shopping cart in the client-server code
>running when you shop at But you're already familiar with
>them, so it helps you deal with using the system: add to cart, remove from
>cart, proceed to check out, ¡¦ It's such an effective metaphor that most
>people don't even realize a difference.
>Note, however, the shopping cart metaphor would be entirely useless for a
>user who was only familiar with the "bazaar" style of shopping: go to one
>vendor for this, another vendor for that, haggle over prices, ¡¦
>When there is an effective metaphor, it can be amazingly effective. It's
>just not always possible to find such a metaphor for every system.
>-- steve
>-----Original Message-----
>From: <systemsafety-bounces_at_xxxxxx >Date: Wednesday, July 15, 2015 8:19 AM
>To: Peter Bernard Ladkin <ladkin_at_xxxxxx >List <systemsafety_at_xxxxxx >Subject: Re: [SystemSafety] Fwd: Re: power plant user interfaces
>It seems to me that HMI "metaphors" can take the form of arrows, needles,
>and/or moving tapes pointing in an intuitive directions (that one might
>expect in other real-world situations) and auditory cues that come from
>the right direction. Also the order in which information is provided to
>the operator can ©ømetaphorically©÷ represent the operator©ös cognitive model
>of how pipes are arranged or valves are located in a processing plant for
>Brian Smith
>>Hash: SHA256
>>On 2015-07-15 03:12 , Les Chambers wrote:
>>> So my point is: the key to a good HMI is excellent metaphor design.
>>That does not fit in any way what I and colleagues have done or have been
>>doing in HMI for the
>>last couple of decades (and for some of them longer). There is a fair
>>amount of math and logic
>>involved. No metaphors.
>>Key to good HMI is rigorous formal analysis. There are other key
>>Prof. Peter Bernard Ladkin, Faculty of Technology, University of
>>Bielefeld, 33594 Bielefeld, Germany
>>Je suis Charlie
>>Tel+msg +49 (0)521 880 7319
>>The System Safety Mailing List
>The System Safety Mailing List
>systemsafety_at_xxxxxx >

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systemsafety_at_xxxxxx Received on Wed Jul 15 2015 - 18:51:18 CEST

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