10: French & Weaver
According to French the fixed features are untenable strawmen. However
schyns believes fixed features to be an influential approach.
French & Weaver believe that is is unlikely that we are born with all
the features we need to have throughout life, features are therefore
learned. However, there is no evidence for this. It is therefore a
widespread working assumption.
Schyns believes that this working assumption is not valid.
Schyns demonstrates which French & Weaver acknowledge:
> that there is a aquisition of new features during catagory learning.
French & Weaver do not follow that the aquisition of new features is a
typical part of catagory learning. French & Weaver argue that the
widespread assumption of fixed feature catagory learning experiment is
supported in the general case of adult category learning.
Schyns states that:
> almost any feature is composed of lower level features.
However, French & Weaver believe :
> that this makes the distinction between primitive and functional
> features difficult, if not impossible to maintain.
> This contradiction between primitive and structures maybe resolved
> by thinking that they are both rationally organized as building
> blocks from which new catagories and concepts maybe constructed.
French & Weaver suggest that it is was wrong of Schyns to:
> demonstrate new feature learning where it is most difficult to
>observe, namely with readily perceived, concrete objects.
French & Weaver argue that working assumption is reasonable because
> if you look at the evolving constraints and
> universally shared experiences with objects
> in the world this suggests that by the time
> of adulthood, most of the primitives
> humans need to handle concrete categories will already have been
> learned which is why we argue that fixed feature approach for the
> learning of concrete categories is a reasonable working assumption.
They finish by concluding that working assumption of fixed categories
in learning is justified. However, there needs to be far more work
done in this area.
Feature based theoriesd of concept formation have two dilemmas.
(1) for many natural concepts it is hard to see how the concept of the
features could be developmentally more basic.
(2) the concept formation must be guided by abstraction heuriotics.
Schyns theory argues that the concepts of the features need not be
developmentally more basic. They don't explain how novel features might
Yet all agree that on one thing :
> a theory of conceptual development has
> to explain how children learn to apply
> category words to roughly the same sort
> of things as others who have learned language.
No two peoples abstracts general concepts form exactly the same class
of instances. Yet people agree on categories. These categories, it is
being argues, maybe innate or shared principles of abstraction.
Grossberg uses adaptive resonance theory ( ART ) to illustrate some
> ART works to bind together features of the group via a bottom up
> adaptive filter that activates a category which represents this new
> combination of features.
i.e. a prototype.
Prototypes are used to match other objects. If the matched object is
good enough the system learns to incorporate a novel boundary of
groupings into learned categories.
There are two levels.
> the lower level deals with new features
> that contribute to the larger categories.
> This higher category level can selectively bind together or fuse
> certain combinations of new features in one contexed and different
> combinations in another.
This process generates large categories and conserves memory
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