[From Bill Powers (2008.11.27.1115 MST)]
Hi, all. My son sent me this, noting that the explanation is the usual computer-output stuff.
http://www.youtube.com/watch?v=_dPlkFPowCc
Best,
Bill P.
[from Gary Cziko 2008/11/27 12:47 CST]
···
On Thu, Nov 27, 2008 at 12:16 PM, Bill Powers powers_w@frontier.net wrote:
[From Bill Powers (2008.11.27.1115 MST)]
Hi, all. My son sent me this, noting that the explanation is the usual computer-output stuff.
Well, there has to be some limits to this “keep your head in the same spot” control system or walking and flying would be very messy!
Bill, I’m guessing you would say that the chicken doesn’t have to have any idea of where it’s body is. All it has to know is where its head is (with visual and/or vestibular feedback) and have the means to keep it there, right?
'Twould be interesting to try this with a hooded or otherwise visually impaired hen. I’ve got friends here in Urbana with chickens, but I don’t think I want to bother them today as they probably have other fowl on their minds.
Rick will probably want to know if chickens can catch fly balls.
Happy Turkey to those CSGnetters in the USA (belated Thanksgiving to our Canadian friends)!
–Gary
[From Bruce Nevin (2008.11.27.1433 EST)]
They evidently are stabilizing the visual image.
This underlies what we perceive as head bobbing as birds walk. There’s not enough mass in the head for it to be the avian correlary of our swinging our arms, and anyway that would suggest some side to side movement of the head with the alternating leg movements. Put a bird on a treadmill and they walk without bobbing their heads.
http://www.loc.gov/rr/scitech/mysteries/pigeon.html
···
From: Control Systems Group Network (CSGnet) [mailto:CSGNET@LISTSERV.ILLINOIS.EDU] On Behalf Of Gary Cziko
Sent: Thursday, November 27, 2008 1:54 PM
To:
CSGNET@LISTSERV.ILLINOIS.EDU
Subject: Re: Chicken control system
[from Gary Cziko 2008/11/27 12:47 CST]
On Thu, Nov 27, 2008 at 12:16 PM, Bill Powers powers_w@frontier.net > wrote:
[From Bill Powers (2008.11.27.1115 MST)] Hi, all. My son sent me this, noting that the explanation is the usual computer-output stuff.Well, there has to be some limits to this “keep your head in the same spot” control system or walking and flying would be very messy!
Bill, I’m guessing you would say that the chicken doesn’t have to have any idea of where it’s body is. All it has to know is where its head is (with visual and/or vestibular feedback) and have the means to keep it there, right?
'Twould be interesting to try this with a hooded or otherwise visually impaired hen. I’ve got friends here in Urbana with chickens, but I don’t think I want to bother them today as they probably have other fowl on their minds.
Rick will probably want to know if chickens can catch fly balls.
Happy Turkey to those CSGnetters in the USA (belated Thanksgiving to our Canadian friends)!
–Gary
[From Bill Powers (2008.11.27.1216 MST)]
Yes, happy Thanksgiving for them as celebrates it.
Gary Cziko 2008/11/27 12:47 CST]
Bill, I'm guessing you would say that the chicken doesn't have to have any idea of where it's body is. All it has to know is where its head is (with visual and/or vestibular feedback) and have the means to keep it there, right?
I'd say the chicken keeps its perception of visual relationships in the room from changing by moving its head relative to its body. Try it. Line up a corner of a near object with some feature of a far object and keep the two objects aligned (shut one eye). You can twist your body sideways while your direction of gaze remains constant both left-right and up-down. We don't have telescoping necks like a chicken, but you can do some compensating for sideways body movements over a limited range.
You can also, standing up, look "straight ahead" and turn your feet and body to the left or right by close to 90 degrees. It feels like moving your body without moving your head. Then you can turn your head to align with the direction your feet are pointing. That feels like turning your head. Or you can do it in the opposite sequence: turn head, then turn body to align with it. When you turn your head, you can think of it as turning your head to one side, or you can redefine "straight ahead" so your head now feels as if it's turned, then turn your head so it is pointing in the new straight ahead direction.
You can also turn your feet to one side keeping your body still, then turn your hips to align with your feet while keeping your shoulders from turning, then turn your shoulders keeping your head still, then turn your head keeping your eyes still -- and finally turn your eyes. At any time you can redefine "straight ahead" to be the way your feet (or any other segments) are pointed.
There's a vaudville dance step in which the tap-dancer bends forward, looking at the audience with the head fairly erect, with the arms swinging sideways alternately and the legs doing a forward running step but without moving (the feet slide on the floor). Everything moves but the head.
PCT Yoga?
Best,
Bill P.
[From Ted Cloak
(2008.11.27.1241 MST)]
OK, what happens if the bird is on a stable perch but is surrounded by
a picture simulating the movement of its surroundings?
[From
Bruce Nevin (2008.11.27.1433 EST)]
They
evidently are stabilizing the visual image.
This
underlies what we perceive as head bobbing as birds walk. There’s not
enough mass in the head for it to be the avian correlary of our swinging our
arms, and anyway that would suggest some side to side movement of the head with
the alternating leg movements. Put a bird on a treadmill and they walk without
bobbing their heads.
http://www.loc.gov/rr/scitech/mysteries/pigeon.html
···
[from Gary Cziko
2008/11/27 12:47 CST]
On Thu, Nov 27, 2008 at 12:16 PM, Bill Powers powers_w@frontier.net wrote:
[From Bill Powers (2008.11.27.1115 MST)]
Hi, all. My son sent me this, noting that the explanation is the usual
computer-output stuff.
Well, there has to be some limits to this “keep your head in the
same spot” control system or walking and flying would be very messy!Bill, I’m guessing you would say that the chicken doesn’t have to have any idea
of where it’s body is. All it has to know is where its head is (with visual
and/or vestibular feedback) and have the means to keep it there, right?'Twould be interesting to try this with a hooded or otherwise visually impaired
hen. I’ve got friends here in Urbana
with chickens, but I don’t think I want to bother them today as they probably
have other fowl on their minds.Rick will probably want to know if chickens can catch fly balls.
Happy Turkey to those
CSGnetters in the USA
(belated Thanksgiving to our Canadian friends)!–Gary
[From Bruce Nevin (2008.11.27.1449
EST)]
Judging from my cockateal, the bird looks around, moves around, does not stay still on the perch, and is more or less disturbed by the motion. More formal experimentation would be required to confirm.
/B
···
From: Control Systems Group Network (CSGnet) [mailto:CSGNET@LISTSERV.ILLINOIS.EDU] On Behalf Of Ted Cloak
Sent: Thursday, November 27, 2008 2:43 PM
To:
CSGNET@LISTSERV.ILLINOIS.EDU
Subject: Re: Chicken control system
[From Ted Cloak (2008.11.27.1241 MST)]
OK, what happens if the bird is on a stable perch but is surrounded by a picture simulating the movement of its surroundings?
[From Bruce Nevin (2008.11.27.1433 EST)]
They evidently are stabilizing the visual image.
This underlies what we perceive as head bobbing as birds walk. There’s not enough mass in the head for it to be the avian correlary of our swinging our arms, and anyway that would suggest some side to side movement of the head with the alternating leg movements. Put a bird on a treadmill and they walk without bobbing their heads.
[from Gary Cziko 2008/11/27 12:47 CST]
On Thu, Nov 27, 2008 at 12:16 PM, Bill Powers <powers_w@frontier.net > wrote:
[From Bill Powers (2008.11.27.1115 MST)]
Hi, all. My son sent me this, noting that the explanation is the usual computer-output stuff.
Well, there has to be some limits to this "keep your head in the same spot" control system or walking and flying would be very messy! Bill, I'm guessing you would say that the chicken doesn't have to have any idea of where it's body is. All it has to know is where its head is (with visual and/or vestibular feedback) and have the means to keep it there, right? 'Twould be interesting to try this with a hooded or otherwise visually impaired hen. I've got friends here in Urbana with chickens, but I don't think I want to bother them today as they probably have other fowl on their minds. Rick will probably want to know if chickens can catch fly balls.Happy Turkey to those CSGnetters in the USA (belated Thanksgiving to our Canadian friends)!
–Gary
OK, what happens if the bird is on a stable perch but is surrounded by a
picture simulating the movement of its
surroundings?
[From Bill Powers (2008.11.27.1252 MST)]
Ted Cloak (2008.11.27.1241 MST)
···
–
Probably something like what happens when you’re on a train and the train
next to you starts moving. Or when you’re at a stop-light and the car
next you moves backward a little while you’re looking at it (I stomp on
the brake).
An excellent way to find out whether it’s the visual image or the
vestibular feedback that’s being controlled.
Best,
Bill P.
Most interesting.
A walking chicken's body is moving "continuously", while its head is
moving "discretely". If you know what I mean. Its view would be
steady->quick jump->steady->quick jump and so forth.
Instead of just moving its body a bit, like what they did in the
video, what about moving its body a little longer? Like holding a
chicken walk from one end of the room to the other. I would like to
see whether it still get the head jump like what it does in walking.
While keeping steady is controlled, this jump probably has something
to do with its walking pattern generator.
Best regards,
Bo
···
2008/11/28 Bill Powers <powers_w@frontier.net>:
[From Bill Powers (2008.11.27.1115 MST)]
Hi, all. My son sent me this, noting that the explanation is the usual
computer-output stuff.http://www.youtube.com/watch?v=_dPlkFPowCc
Best,
Bill P.
[From Bill Powers (2008.12.01 1116 MST)]
A walking chicken's body is moving "continuously", while its head is
moving "discretely". If you know what I mean. Its view would be
steady->quick jump->steady->quick jump and so forth.
I think a chicken's eyes are fixed in its head. That would mean that we are seeing "head-saccades" like the eye-jumps in human vision. Human vision blanks out during the saccades; maybe the chicken's does, too.
Instead of just moving its body a bit, like what they did in the
video, what about moving its body a little longer? Like holding a
chicken walk from one end of the room to the other. I would like to
see whether it still get the head jump like what it does in walking.
While keeping steady is controlled, this jump probably has something
to do with its walking pattern generator.
Maybe, maybe not. I once developed a model of human eye movements in which the normal state of the eye was "locked on to visual scene," and the jumps occurred when the fixation control system was momentarily shut off, allowing a jump to a new position. The new position was set when attention was moved to a new place in the visual field while the eye was kept from moving by the control system that stabilized the visual field.
1. Eye is locked to visual scene by fast high-gain fixation control system.
2. Attention shifts off foveal position to new position away from center, setting reference eye position to new setting. Eye does not move due to fixation control system.
3. Fixation control system is turned off and visual signals to higher systems are disabled.
4. Eye automatically slews to new position.
5. Fixation control system turned back on. Go to step 1.
This would imply that in the chicken, the head-saccades would occur even if the chicken was being carried across the room. I'm guessing that the visual system is independent of the walking system. However, there would be a relationship between the individual steps and the saccades, because whenever a step resulted in reaching a limit of movement of the head relative to the body, a higher system would select a new reference position for locking on to the visual scene.
far far far far
near near near near
>--- 1 step-->--- 1 step-->-- 1 step-->
Hey, don't they have any chickens in Shanghai?
Best,
Bill P.
Hey, don't they have any chickens in Shanghai?
Hard to find an alive one around~
I did a quick search and found this phenomenon is called "head-bobbing":
···
====
Visual control of head movements during avian locomotion
MARK B. FRIEDMAN
THE impression that pigeons, chickens, and many other common birds bob
their heads backward and forward as they walk is compelling but
illusory. In reality, the walking bird thrusts its head forward, then
holds it nearly stationary while the neck retracts and the body
catches up. The head moves backward and forward with respect to the
body, but moves only forward in the environment. Although this was
demonstrated on film more than 40 years ago1, theorists concerned with
the evolution of visual systems2e$B!]e(B4 continue to suggest that a back and
forth oscillation of the head is important in avian vision.
Going through the related articles on Google Scholar, I found another
interesting publication
====
The Optokinetic Basis of Head-bobbing in the Pigeon
B. J. FROST 1
1 Department of Psychology, Queen's University, Kingston, Ontario, Canada
1. Head-bobbing of pigeons during walking and landing was studied
using high-speed motion photography.
2. The analysis of film records indicated that head-bobbing whilst
walking consists of two phases: one where the head is 'locked' in
space but moves backward relative to its forward moving body; and
another where it is thrust rapidly forward to a new position.
3. The fact that head-bobbing is abolished when pigeons walk on a
treadmill suggests it is primarily a visual response rather than an
equilibratory response.
4. Data are presented which show that stabilization during the 'lock'
phase allows a small degree of slippage which is the probable source
of error signals for compensatory head movements.
5. The head-bobbing that appears to occur during landing is shown to
be illusory.
Submitted on September 19, 1977
I attached two pages of it for your evaluation. It said "When pigeons
were placed on the treadmill, and walking induced, the normal hold and
thrust type of head-bobbing described above was abolished. If the
bird's walking velocity matched the belt velocity then no head-bobbing
movements were produced. Normally, however, there were minor momentary
discrepancies between walking speed and belt speed, resulting in small
forward and backward oscillations of the body which in turn
occasionally precipitated a slight adjustment in head position."
"Some time later we attempted to film this behaviour but with limited
success, possibly because the treadmill no longer operated reliably
and smoothly at very slow speeds. Nevertheless, data similar to that
presented in Fig. 4 were obtained, where it can be seen that at
relatively slow speeds where no walking is induced, head stabilization
occurs but is less than perfect. Slippage of approximately 3-6 mm/s
occurs and results in small forward head thrusts. However, a gradual
change in head position relative to body position, similar to that
reported above, can be seen in this figure."
From these experiments, walking might be a factor but not a major
factor in "head-bobbing" of pigeons. As this is published 30 years
ago, more precise experiments must have been done.
Best,
Bo
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[From Bill Powers (2008.12.02.0854 MST)]
> [Bill]: Hey, don't they have any chickens in Shanghai?
Hard to find an alive one around~
I did a quick search and found this phenomenon is called "head-bobbing":
Well done. It looks as if the "bobbing" of the head is simply the attempt to stabilize the visual image to keep it from moving on the retina. This is needed, of course for visual acuity, so reorganization (individual or species) is probably the underlying explanation.
Best,
Bill P.
P.S. I filled in another recommendation form, this one for the University of Maryland.
···
At 09:12 PM 12/2/2008 +0800, Wang Bo wrote: