# Language; Kadri

**URL:** <http://discourse.iapct.org/t/language-kadri/6204>\
**Category:** CSG1993\
**Created:** [May 20, 1993, 4:18pm UTC](http://discourse.iapct.org/t/language-kadri/6204 "1993-05-20T16:18:23Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![William\_T\_Powers2](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/w/c67d28/32.png) [@William\_T\_Powers2](http://discourse.iapct.org/u/William_T_Powers2)\
**Post date:** [May 20, 1993, 4:18pm UTC](http://discourse.iapct.org/t/language-kadri/6204/1 "1993-05-20T16:18:23Z")

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[From Bill Powers (930520.0830 MDT)]

Rick Marken (930519.1400) --

Rick, I think you're coming closer to elucidating an insight  
about language.

talking to Bruce Nevin:

> I presume you are using the term "reference perception" to  
> refer to reference signals or to the reference state of a  
> controlled perception. In either case, these are not set "based  
> upon experience of trial and error";

Right, reference perceptions are VARIED, not SET. This seems to  
be in conflict with the idea that when we want to indicate a  
certain kind of fruit, we say "apple." That sounds like a fixed  
means of indicating a particular thing -- what has been described  
as a fixed reference signal.

I think that there is some confusion (spread around) about when  
to speak of signals and when to speak of functions. What is  
learned is not a signal, but a function. If, when you look at a  
certain arrangement of plastic and glass in front of you, you  
think "computer," it is not the signal "computer" (a perception)  
that you have learned, but the perceptual function that  
translates a set of perceptions of one kind (visual images) into  
a set of perceptions of another kind (words). This function can  
convert many different input arrangements into the same output  
signal; that's the nature of a function.

Whether we imagine the mechanism to involve memory association or  
any other principle is irrelevant. What matters is that  
reorganization has brought into being a DEVICE, a physical hookup  
of neurons, which, when presented with a set of inputs, produces  
signals as outputs. If the input signals vary in a particular  
way, the output signal will vary. If they vary in an orthogonal  
way, the output signal will remain constant.

In our one-signal-one-perception model, this notion causes some  
problems, because at a high enough level, signals seem to  
indicate categories that are either present or not present. How  
does a control system vary a signal that can be only on or off?  
This bring to mind something that Marc Olsen brought up some  
months ago -- place-coded perceptions. If there are categorical  
perceptions associated with distinct words, the only way to vary  
such a perception is to vary \_which perceptual function\_ is  
involved. If the higher-order task is to name something, the only  
way to vary the name is to scan through different systems of  
lower order, each of which is specialized to produce a perception  
of a particular name. So instead of varying the \_amplitude\_ of an  
output signal that is sent to a fixed subset of lower-order  
comparators, the output function varies the \_destination\_ of the  
output signal.

This implies an output function with a specific property. As the  
scalar error signal varies in amplitude, the output function  
converts the amplitude not into an amplitude of a fixed output  
signal, but into activation of one output signal in an array of  
possible output signals. That is, if the error signal is between  
e0 and e1, output A is produced; if between e1 and e2, output B  
is produced, and so forth: a different output signal for each  
subrange of the error signal.

The way in which this conversion takes place creates an ordering  
of the output signals; as the error signals rise and fall, the  
outputs are selected in a specific order that always remains the  
same. Consider selecting a phrase from the set "none, a little,  
some, pretty much, a lot, an abundance." This set is ordered in a  
way that goes with an analogue amount. If the analogue amount  
increases, we move to the right in the list; if it decreases, we  
move to the left. Moving right or left corresponds to selecting  
different control systems for producing these different phrases  
in perception.

We haven't tried to model any control systems that work this way.  
But some day I think we'll have to try. One reason is the way the  
visual systems seem to be organized. There is preservation of the  
mapping of the retina through many layers in the visual system.  
Because of this mapping, a variable like position (on the retina)  
is represented not by a single signal of variable magnitude, but  
by the movement of a locus of activation across the neural maps  
of the retina. Retinal position, at least at the level of the  
midbrain, is simply preserved as a position in a network. It may  
well be that position is being preserved until a level is reached  
where it can be converted into a single signal of variable  
magnitude. But in visual tracking, which appears to be a rather  
low-level process, setting a position reference signal may well  
amount to sending a reference signal to a specific place in the  
network, with the tracking action then moving the locus of  
retinal activation (filtered through an object-recognizer?) to  
that place. The error signal is derived from the distance between  
two points in the map.

On the other hand, the mapped position could easily be translated  
into a single signal if a neuron received inputs from locations  
spaced across the map, with the weights increasing with distance  
across the map. I don't think we're in a position yet to guess  
how it's really done. Our canonical model is at least  
functionally equivalent, because it does predict the overall  
result properly.

My point is that the functions that are learned may be  
accomplished in ways that we haven't discussed much, and that may  
have an application to problems of modeling language. But the  
fact remains that signals are VARIABLES, and what is learned, as  
Rick is pointing out, is not a signal, but a function that  
creates relationships between signals.

We have to distinguish between the form of a function that  
creates a perceptual signal dependent on other perceptions, and  
the value that the signal happens to have at a given time.

> **···**
>
> -------------------------------------------------------------  
> Cliff Joslyn (930519) --
> 
> Cliff, your dateline is confusing. What I'm used to is an opening  
> line that says [From \<name of the originator of this post\>], with  
> subsequent subheads that say \<originator of the post, with date-  
> time stamp, whose comments I am commenting upon\>.
> 
> If you think it's worthwhile trying to get any more sense out of  
> Faisal Kadri, he's your baby. Right now, I don't feel much  
> motivation to see any more than you reported.  
> -------------------------------------------------------------  
> Best to all,
> 
> Bill P.