[xemacs-hg @ 2002-05-28 08:44:22 by ben] merge my stderr-proc ws make-docfile.c: Fix places where we forget to check for EOF. code-init.el: Don't use CRLF conversion by default on process output. CMD.EXE and friends work both ways but Cygwin programs don't like the CRs. code-process.el, multicast.el, process.el: Removed. Improvements to call-process-internal: -- allows a buffer to be specified for input and stderr output -- use it on all systems -- implement C-g as documented -- clean up and comment call-process-region uses new call-process facilities; no temp file. remove duplicate funs in process.el. comment exactly how coding systems work and fix various problems. open-multicast-group now does similar coding-system frobbing to open-network-stream. dumped-lisp.el, faces.el, msw-faces.el: Fix some hidden errors due to code not being defined at the right time. xemacs.mak: Add -DSTRICT. ================================================================ ALLOW SEPARATION OF STDOUT AND STDERR IN PROCESSES ================================================================ Standard output and standard error can be processed separately in a process. Each can have its own buffer, its own mark in that buffer, and its filter function. You can specify a separate buffer for stderr in `start-process' to get things started, or use the new primitives: set-process-stderr-buffer process-stderr-buffer process-stderr-mark set-process-stderr-filter process-stderr-filter Also, process-send-region takes a 4th optional arg, a buffer. Currently always uses a pipe() under Unix to read the error output. (#### Would a PTY be better?) sysdep.h, sysproc.h, unexfreebsd.c, unexsunos4.c, nt.c, emacs.c, callproc.c, symsinit.h, sysdep.c, Makefile.in.in, process-unix.c: Delete callproc.c. Move child_setup() to process-unix.c. wait_for_termination() now only needed on a few really old systems. console-msw.h, event-Xt.c, event-msw.c, event-stream.c, event-tty.c, event-unixoid.c, events.h, process-nt.c, process-unix.c, process.c, process.h, procimpl.h: Rewrite the process methods to handle a separate channel for error input. Create Lstreams for reading in the error channel. Many process methods need change. In general the changes are fairly clear as they involve duplicating what's used for reading the normal stdout and changing for stderr -- although tedious, as such changes are required throughout the entire process code. Rewrote the code that reads process output to do two loops, one for stdout and one for stderr. gpmevent.c, tooltalk.c: set_process_filter takes an argument for stderr. ================================================================ NEW ERROR-TRAPPING MECHANISM ================================================================ Totally rewrite error trapping code to be unified and support more features. Basic function is call_trapping_problems(), which lets you specify, by means of flags, what sorts of problems you want trapped. these can include -- quit -- errors -- throws past the function -- creation of "display objects" (e.g. buffers) -- deletion of already-existing "display objects" (e.g. buffers) -- modification of already-existing buffers -- entering the debugger -- gc -- errors->warnings (ala suspended errors) etc. All other error funs rewritten in terms of this one. Various older mechanisms removed or rewritten. window.c, insdel.c, console.c, buffer.c, device.c, frame.c: When creating a display object, added call to note_object_created(), for use with trapping_problems mechanism. When deleting, call check_allowed_operation() and note_object deleted(). The trapping-problems code records the objects created since the call-trapping-problems began. Those objects can be deleted, but none others (i.e. previously existing ones). bytecode.c, cmdloop.c: internal_catch takes another arg. eval.c: Add long comments describing the "five lists" used to maintain state (backtrace, gcpro, specbind, etc.) in the Lisp engine. backtrace.h, eval.c: Implement trapping-problems mechanism, eliminate old mechanisms or redo in terms of new one. frame.c, gutter.c: Flush out the concept of "critical display section", defined by the in_display() var. Use an internal_bind() to get it reset, rather than just doing it at end, because there may be a non-local exit. event-msw.c, event-stream.c, console-msw.h, device.c, dialog-msw.c, frame.c, frame.h, intl.c, toolbar.c, menubar-msw.c, redisplay.c, alloc.c, menubar-x.c: Make use of new trapping-errors stuff and rewrite code based on old mechanisms. glyphs-widget.c, redisplay.h: Protect calling Lisp in redisplay. insdel.c: Protect hooks against deleting existing buffers. frame-msw.c: Use EQ, not EQUAL in hash tables whose keys are just numbers. Otherwise we run into stickiness in redisplay because internal_equal() can QUIT. ================================================================ SIGNAL, C-G CHANGES ================================================================ Here we change the way that C-g interacts with event reading. The idea is that a C-g occurring while we're reading a user event should be read as C-g, but elsewhere should be a QUIT. The former code did all sorts of bizarreness -- requiring that no QUIT occurs anywhere in event-reading code (impossible to enforce given the stuff called or Lisp code invoked), and having some weird system involving enqueue/dequeue of a C-g and interaction with Vquit_flag -- and it didn't work. Now, we simply enclose all code where we want C-g read as an event with {begin/end}_dont_check_for_quit(). This completely turns off the mechanism that checks (and may remove or alter) C-g in the read-ahead queues, so we just get the C-g normal. Signal.c documents this very carefully. cmdloop.c: Correct use of dont_check_for_quit to new scheme, remove old out-of-date comments. event-stream.c: Fix C-g handling to actually work. device-x.c: Disable quit checking when err out. signal.c: Cleanup. Add large descriptive comment. process-unix.c, process-nt.c, sysdep.c: Use QUIT instead of REALLY_QUIT. It's not necessary to use REALLY_QUIT and just confuses the issue. lisp.h: Comment quit handlers. ================================================================ CONS CHANGES ================================================================ free_cons() now takes a Lisp_Object not the result of XCONS(). car and cdr have been renamed so that they don't get used directly; go through XCAR(), XCDR() instead. alloc.c, dired.c, editfns.c, emodules.c, fns.c, glyphs-msw.c, glyphs-x.c, glyphs.c, keymap.c, minibuf.c, search.c, eval.c, lread.c, lisp.h: Correct free_cons calling convention: now takes Lisp_Object, not Lisp_Cons chartab.c: Eliminate direct use of ->car, ->cdr, should be black box. callint.c: Rewrote using EXTERNAL_LIST_LOOP to avoid use of Lisp_Cons. ================================================================ USE INTERNAL-BIND-* ================================================================ eval.c: Cleanups of these funs. alloc.c, fileio.c, undo.c, specifier.c, text.c, profile.c, lread.c, redisplay.c, menubar-x.c, macros.c: Rewrote to use internal_bind_int() and internal_bind_lisp_object() in place of whatever varied and cumbersome mechanisms were formerly there. ================================================================ SPECBIND SANITY ================================================================ backtrace.h: - Improved comments backtrace.h, bytecode.c, eval.c: Add new mechanism check_specbind_stack_sanity() for sanity checking code each time the catchlist or specbind stack change. Removed older prototype of same mechanism. ================================================================ MISC ================================================================ lisp.h, insdel.c, window.c, device.c, console.c, buffer.c: Fleshed out authorship. device-msw.c: Correct bad Unicode-ization. print.c: Be more careful when not initialized or in fatal error handling. search.c: Eliminate running_asynch_code, an FSF holdover. alloc.c: Added comments about gc-cons-threshold. dialog-x.c: Use begin_gc_forbidden() around code to build up a widget value tree, like in menubar-x.c. gui.c: Use Qunbound not Qnil as the default for gethash. lisp-disunion.h, lisp-union.h: Added warnings on use of VOID_TO_LISP(). lisp.h: Use ERROR_CHECK_STRUCTURES to turn on ERROR_CHECK_TRAPPING_PROBLEMS and ERROR_CHECK_TYPECHECK lisp.h: Add assert_with_message. lisp.h: Add macros for gcproing entire arrays. (You could do this before but it required manual twiddling the gcpro structure.) lisp.h: Add prototypes for new functions defined elsewhere.

STUDIES FIND REWARD OFTEN NO MOTIVATOR

Creativity and intrinsic interest diminish if task is done for gain

By Alfie Kohn
Special to the Boston Globe
[reprinted with permission of the author
 from the Monday 19 January 1987 Boston Globe]

In the laboratory, rats get Rice Krispies.  In the classroom the top
students get A's, and in the factory or office the best workers get
raises.  It's an article of faith for most of us that rewards promote
better performance.

But a growing body of research suggests that this law is not nearly as
ironclad as was once thought.  Psychologists have been finding that
rewards can lower performance levels, especially when the performance
involves creativity.

A related series of studies shows that intrinsic interest in a task -
the sense that something is worth doing for its own sake - typically
declines when someone is rewarded for doing it.

If a reward - money, awards, praise, or winning a contest - comes to
be seen as the reason one is engaging in an activity, that activity
will be viewed as less enjoyable in its own right.

With the exception of some behaviorists who doubt the very existence
of intrinsic motivation, these conclusions are now widely accepted
among psychologists.  Taken together, they suggest we may unwittingly
be squelching interest and discouraging innovation among workers,
students and artists.

The recognition that rewards can have counter-productive effects is
based on a variety of studies, which have come up with such findings
as these: Young children who are rewarded for drawing are less likely
to draw on their own that are children who draw just for the fun of
it.  Teenagers offered rewards for playing word games enjoy the games
less and do not do as well as those who play with no rewards.
Employees who are praised for meeting a manager's expectations suffer
a drop in motivation.

Much of the research on creativity and motivation has been performed
by Theresa Amabile, associate professor of psychology at Brandeis
University.  In a paper published early last year on her most recent
study, she reported on experiments involving elementary school and
college students.  Both groups were asked to make "silly" collages.
The young children were also asked to invent stories.

The least-creative projects, as rated by several teachers, were done
by those students who had contracted for rewards.  "It may be that
commissioned work will, in general, be less creative than work that is
done out of pure interest," Amabile said.

In 1985, Amabile asked 72 creative writers at Brandeis and at Boston
University to write poetry.  Some students then were given a list of
extrinsic (external) reasons for writing, such as impressing teachers,
making money and getting into graduate school, and were asked to think
about their own writing with respect to these reasons.  Others were
given a list of intrinsic reasons:  the enjoyment of playing with
words, satisfaction from self-expression, and so forth.  A third group
was not given any list.  All were then asked to do more writing.

The results were clear.  Students given the extrinsic reasons not only
wrote less creatively than the others, as judged by 12 independent
poets, but the quality of their work dropped significantly.  Rewards,
Amabile says, have this destructive effect primarily with creative
tasks, including higher-level problem-solving.  "The more complex the
activity, the more it's hurt by extrinsic reward," she said.

But other research shows that artists are by no means the only ones
affected.

In one study, girls in the fifth and sixth grades tutored younger
children much less effectively if they were promised free movie
tickets for teaching well.  The study, by James Gabarino, now
president of Chicago's Erikson Institute for Advanced Studies in Child
Development, showed that tutors working for the reward took longer to
communicate ideas, got frustrated more easily, and did a poorer job in
the end than those who were not rewarded.

Such findings call into question the widespread belief that money is
an effective and even necessary way to motivate people.  They also
challenge the behaviorist assumption that any activity is more likely
to occur if it is rewarded.  Amabile says her research "definitely
refutes the notion that creativity can be operantly conditioned."

But Kenneth McGraw, associate professor of psychology at the
University of Mississippi, cautions that this does not mean
behaviorism itself has been invalidated.  "The basic principles of
reinforcement and rewards certainly work, but in a restricted context"
- restricted, that is, to tasks that are not especially interesting.

Researchers offer several explanations for their surprising findings
about rewards and performance.

First, rewards encourage people to focus narrowly on a task, to do it
as quickly as possible and to take few risks.  "If they feel that
'this is something I have to get through to get the prize,' they're
going to be less creative," Amabile said.

Second, people come to see themselves as being controlled by the
reward.  They feel less autonomous, and this may interfere with
performance.  "To the extent one's experience of being
self-determined is limited," said Richard Ryan, associate psychology
professor at the University of Rochester, "one's creativity will be
reduced as well."

Finally, extrinsic rewards can erode intrinsic interest.  People who
see themselves as working for money, approval or competitive success
find their tasks less pleasurable, and therefore do not do them as
well.

The last explanation reflects 15 years of work by Ryan's mentor at the
University of Rochester, Edward Deci.  In 1971, Deci showed that
"money may work to buy off one's intrinsic motivation for an activity"
on a long-term basis.  Ten years later, Deci and his colleagues
demonstrated that trying to best others has the same effect.  Students
who competed to solve a puzzle quickly were less likely than those who
were not competing to keep working at it once the experiment was over.

Control plays role

There is general agreement, however, that not all rewards have the
same effect.  Offering a flat fee for participating in an experiment -
similar to an hourly wage in the workplace - usually does not reduce
intrinsic motivation.  It is only when the rewards are based on
performing a given task or doing a good job at it - analogous to
piece-rate payment and bonuses, respectively - that the problem
develops.

The key, then, lies in how a reward is experienced.  If we come to
view ourselves as working to get something, we will no longer find
that activity worth doing in its own right.

There is an old joke that nicely illustrates the principle.  An
elderly man, harassed by the taunts of neighborhood children, finally
devises a scheme.  He offered to pay each child a dollar if they would
all return Tuesday and yell their insults again.  They did so eagerly
and received the money, but he told them he could only pay 25 cents on
Wednesday.  When they returned, insulted him again and collected their
quarters, he informed them that Thursday's rate would be just a penny.
"Forget it," they said - and never taunted him again.

Means to and end

In a 1982 study, Stanford psychologist Mark L. Lepper showed that any
task, no matter how enjoyable it once seemed, would be devalued if it
were presented as a means rather than an end.  He told a group of
preschoolers they could not engage in one activity they liked until
they first took part in another.  Although they had enjoyed both
activities equally, the children came to dislike the task that was a
prerequisite for the other.

It should not be surprising that when verbal feedback is experienced
as controlling, the effect on motivation can be similar to that of
payment.  In a study of corporate employees, Ryan found that those who
were told, "Good, you're doing as you /should/" were "significantly
less intrinsically motivated than those who received feedback
informationally."

There's a difference, Ryan says, between saying, "I'm giving you this
reward because I recognize the value of your work" and "You're getting
this reward because you've lived up to my standards."

A different but related set of problems exists in the case of
creativity.  Artists must make a living, of course, but Amabile
emphasizes that "the negative impact on creativity of working for
rewards can be minimized" by playing down the significance of these
rewards and trying not to use them in a controlling way.  Creative
work, the research suggests, cannot be forced, but only allowed to
happen.

/Alfie Kohn, a Cambridge, MA writer, is the author of "No Contest: The
Case Against Competition," recently published by Houghton Mifflin Co.,
Boston, MA.  ISBN 0-395-39387-6. /