From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Eric S. Raymond" Newsgroups: gmane.emacs.devel Subject: Ergonomics and neurology for interface designers Date: Tue, 25 Nov 2014 08:22:11 -0500 Organization: Eric Conspiracy Secret Labs Message-ID: <20141125132210.GA10466@thyrsus.com> References: <20141124083310.GA29913@thyrsus.com> <87zjbh3r98.fsf@fencepost.gnu.org> <20141124094929.GA32148@thyrsus.com> <87k32k51ka.fsf@fencepost.gnu.org> <20141124104616.GA1744@thyrsus.com> <87fvd8steg.fsf@gmx.de> <20141124130355.GA5432@thyrsus.com> <87bnnwqtfi.fsf@gmx.de> <20141125025054.GA20793@thyrsus.com> <877fyj4w45.fsf@fencepost.gnu.org> Reply-To: esr@thyrsus.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1416921776 8299 80.91.229.3 (25 Nov 2014 13:22:56 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 25 Nov 2014 13:22:56 +0000 (UTC) Cc: Michael Albinus , emacs-devel@gnu.org To: David Kastrup Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Nov 25 14:22:50 2014 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XtG4v-0002AS-W4 for ged-emacs-devel@m.gmane.org; Tue, 25 Nov 2014 14:22:50 +0100 Original-Received: from localhost ([::1]:57140 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XtG4v-00011L-HH for ged-emacs-devel@m.gmane.org; Tue, 25 Nov 2014 08:22:49 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:36809) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XtG4T-0000vz-VL for emacs-devel@gnu.org; Tue, 25 Nov 2014 08:22:26 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XtG4P-0002QP-Km for emacs-devel@gnu.org; Tue, 25 Nov 2014 08:22:21 -0500 Original-Received: from static-71-162-243-5.phlapa.fios.verizon.net ([71.162.243.5]:44747 helo=snark.thyrsus.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XtG4K-0002N9-P1; Tue, 25 Nov 2014 08:22:12 -0500 Original-Received: by snark.thyrsus.com (Postfix, from userid 1000) id 089A5384126; Tue, 25 Nov 2014 08:22:11 -0500 (EST) Content-Disposition: inline In-Reply-To: <877fyj4w45.fsf@fencepost.gnu.org> X-Eric-Conspiracy: There is no conspiracy User-Agent: Mutt/1.5.21 (2010-09-15) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 71.162.243.5 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:178235 Archived-At: David Kastrup : > I don't think that the numbers you throw in here carry a lot of meaning. > As a musician, I certainly have to be able to produce and recognize runs > with individual notes shorter than 0.17 seconds. > > The speed typing record is at 216 words per minute. That's words, not > letters. > > So whether or not those kinds of delay turn out relevant in practice > very much depends on which tasks with what kind of interactivity they > appear in. Blanket musings about some "speed of thought" are > meaningless. As you say, context matters a lot. The 0.17sec ergonomic latency threshold is specific to human-computer interfaces; it was discovered by Jef Raskin during the early design studies that led to the Macintosh interface, and has been experimentally confirmed pretty solidly. I'm a musician too, and music does indeed have time granularity finer than the reflex-arc time. This is possible (as is speed typing and pitching baseballs) because humans have the ability to compose action sequences with finer time granularity and ship them to a limb for execution. In effect, we do downloadable motion subroutines. (By the way, other animals - even higher primates - are not very good at this. There is an interesting and plausible theory that the ability developed in early hominids as an adaptation for throwing rocks at small game, well before we became tool-using cursorial hunters of large game. And that the same action-buffering circuitry was later recruited for pattern recognition in language, music, and mathematics - getting good at throwing, in effect, pre-adapted us for abstract intelligence.) Music fools us. The ear can hear with finer time resolution than spinal-reflex-arc time, so we think musical patterns like 1/32 drumbeats are being generated by an action/reaction process that loops faster than humans are actually capable of. In reality, a skilled musician is not controlling every motion through an action/reaction loop - he or she is shipping those precomposed sequences. What humans cannot do is take sensory input, process, and then *react* faster than spinal-reflex-arc time! Raskin's basic discovery was that if you throw a mockup of your application start controls on the display, you have a minimum of 0.17 seconds to finish initializing the real controls before a human is capable of noticing and then trying to do something. -- Eric S. Raymond