Topics

   
 


1.  The blind mention aspects of perspectives frequently,
    notably the observer's vantage point.

2.  Vision's use of perspective has some "tolerance" or
    "laxity".  We use the angle subtneded by an object.  But
    a picture of a 3-D object subtending 15o may be observed
    at less than 1o or more than 36o and still look quite good.

    Curiosly, pictures of 3-D objects subtending 0o (parallel
    perspective) or 36o (wide-angle views) cannot be 
    observed over 0-36o and still look acceptable.  Only 
    "middling subtenses" such as 15o have very wide
    tolerance.  They are "robust".

3.  Touch may use some aspects of perspective, including 
    what faces the vantage point, the angle made by large 
    objects at the vantage point, and foreshortening.  Indeed,
    vision and touch may share a common spatial sense.

4.  Evidence:  BOOST adults were asked to draw 3-D
    objects (blocks with L, T and Y shapes).  They used
    many devices to show the depth or thickness of the
    object, notably "extra lines" besides outlining the L, T &
    Y shapes, and foldout.  Some used obliques and lines 
    getting thinner when sked to show the object's
    orientation.

5.  What the BOOST audlts were missing was the role of the
    orientation of the pictures's surface.

6.  Evidence:  Pointing tasks:  Perspective depends on
    direction.  Blind people succeed at using convergence to 
    show objects receding and changing direction.  (Loomis;
    Landau and Gleitman; Kennedy, Girard, Campbell).

7.  Evidence:  Judgement tasks:  Kennedy & Gabias. 
    Drawins of tables can be made in different ways,
    depending on the system of perspective employed.

    Blind subjects assign ages to the systems appropriately
    and match drawins of different objects aptly.

8.  Evidence:  Perspective - taking tasks:  Heller & Kennedy.
    In Piaget's "three-mountains" tasks, blind subjects 
    appreciate how to draw 3 objects from different vantage 
    points.

9.  Evidence:  Klatzky et al show early and late blind 
    subjects do equally well on "short-cut" walking tasks,
    completing a triangular route.

10. Evidence:  Millar finds (like Dodds et al) blind children
    draw comlex routes as straight line, with "landmarks".
    But she finds the child can draw the route's shape, if 
    asked.

11. Assignment:  We can "code" space in various ways - but 
    also we can paraphrase it.  Also, a "similar" system (e.g.
    clockface) can be employed - because it is spatial.

12. Evidence:  Kerr finds blind act like sighted subjects on a
    mental spatial imagery task, but are a bit slower.  (Hollins
    find the blind are more 3-D in their imagery, the longer
    they have been blind).

13. Summary:  Perspective is a principle of SPACE.
    Therefore, perspective is also a principle of TOUCH.

        
 

This page was designed and is maintained by William Barek, CITD - Bladen Library.
E-mail: barek@macpost.scar.utoronto.ca