Movement-produced Stimulation in the Development

of Visually Guided Behavior

Richard Held & Alan Hein

1963

Bell Ringer

• After viewing the clip by the famous, Zimbardo, briefly explain the difference between sensation and perception.

• Sensation and Perception

Background

• Sensation is the process of bringing information from the outside world into the body and to the brain.

– Process of sensing our environment through touch, taste, sight, sound, and smell. Requires sensory receptors.

– This information is sent to our brains in raw form where perception comes into play.

Background

• Perception can be defined as the process of selecting, organizing, and interpreting the information brought to the brain by the senses.

• We are concerned with the development of perception

Background

• Restricting the visual experience of newbornanimals affects the development of spatial perception and co-ordination – Reisen (1961).

• Case studies of people who have recovered their sight after being blind for many years (Gregory & Wallace, 1963), suggest that adult human perception is malleable.

• Adult human perception also displays some plasticity as people can adapt to new perceptual information. Held (1955) demonstrated this adaptation experimentally with auditory information (sound) and Held & Hein (1958) with visual information.

Background

• The debate between nature and nurture is the basis of most research into the development of perception.

• There are five ways in which psychologists have attempted to study this debate:

– by studying human babies, or neonates

– by studying cataract patients

– by studying animals

– by studying different cultures

– by studying adaptation

Background

• Those who support the nature view point believe that humans are born with all their perceptual functions ready to be used

– Bottom up theories of processing: also known as "small chunk" processing, suggests that we perceive our environment by starting with the smaller, more fine details then building upward until we have a solid representation of it in our minds

Background

• Those who support the nurture view believe that perceptual abilities have to be learned and adapted to

– Top down theories of processing: also known as "large chunk" processing, states that we form perceptions of our environment by starting with the larger concepts and then working our way down to the finer details of that concept

Reflective

• So which is it? Bottom up or top down? The debate continues. Within your groups, pick a side. Do you believe we process the world from the bottom up or from the top down? Provide an argument showing which way your group believes we see the world. You must provide rationale with at least three solid examples!

Bell Ringer

• Put a pair of distortion glasses on and throw a tennis ball to each other.

• How many times does it take you to throw the ball until you can successful catch the ball?

• Did you find this activity to be difficult or did your perception adapt quickly?

AIM

• To test whether being moved around and seeing the environment change was sufficient to develop visually guided behaviour, such as depth perception, or whether the individual needed to experience self-generated movement in order to learn.

• Whether the individual needed to move themselves around at the same time as experiencing visual changes in order to acquire perceptual skills.

HYPOTHESIS

• Self-produced movement and concurrent visual feedback are essential for the development of visually-guided behaviour.

PROCEDURE

• SubjectsTen pairs of kittens, each pair from a different litter – reared in similar conditions. In each pair, one was ‘active’ (A) and one was ‘passive’ (P).

Eight pairs (Group X) were reared in darkness until 8-12 weeks. They were then exposed to the apparatus for 3 hours daily.

Two pairs (Group Y) were exposed 3 hours per day from 2-10 weeks of age, to the patterned interior of the laboratory while restrained –could move head but not body.

When not exposed all subjects were kept in dark cages together with their mothers and litter mates.

IV – condition in which they were placed - Active or PassiveDP - response

PROCEDURE

• During exposure to the visual environment, the kitten pair was attached to a freely-moving ‘roundabout’ which was propelled by the movements of kitten A because its body was firmly but flexibly attached to the apparatus. This animal could:

PROCEDURE

• This animal could:– rotate clockwise or anticlockwise around the center– go towards or away from the centre (i.e. out to the edge or back

in)– move up or down (e.g. stretch up or crouch down) turn left or

right

Kitten P was firmly attached to the roundabout but it was carried in a basket so could not control its own movement. Through a mechanical system, kitten P was moved in exactly the same way as kitten A. So if kitten A walked clockwise, moved to the edge, then back to the centre, then moved upwards and dropped down again, so did kitten P. Kitten P’s legs stuck through the bottom of the basket so, although he could not move them, they could slide along the floor as he moved.

PROCEDURE

• Neither kitten could see their own limbs although both could move their heads freely.The apparatus was housed in a cylinder with black, white and metal-coloured vertical strips on the walls inside. The center of the roundabout, which was also striped, prevented the kittens from seeing each other.

The pairs spent 3 hours per day in the experimental apparatus, beginning when the active kitten was big enough to move the ‘roundabout’ and continuing for six weeks.

PROCEDURE

• The kittens’ perceptual abilities were tested in an illuminated laboratory. There were three tests of visually guided behaviour:

– Visually-guided paw placement

– Avoidance of a visual cliff

– Blink to an approaching object

Bell Ringer

• Ted Talk- The Power of Perception

PROCEDURE

• visually-guided paw placement: the kitten was held by the experimenter with its head and forelegs free and was carried down to the edge of the table. A kitten with normal visual experience extends its paws ready to make contact with the surface – six repetitions were performed after each daily exposure for all subjects, on the first day one of each pair, (A), displayed visual paw placing.

• avoidance of a visual cliff: the kitten is placed on the central ‘bridge’ from which it can stay still or walk onto either the ‘shallow’ or ‘deep’ side. A kitten with normal visual experience avoids the ‘deep’ side . This was repeated six times – after which (P) was placed in an illuminated room for 48 hours – after which subjects were tested for visual placing and cliff. Testing differed for pairs of (P) – from day two P was not placed on the cliff , but instead the passive exposure was continued for 3 hours daily for a total of 126 hours. The paw placing and visual cliffs tests were then administered to P

• blink to an approaching object: the kitten was held still in a standing position and the experimenter brought his hand quickly towards the kitten’s face (stopping just in front of it). A kitten with normal visual experience blinks in response.

PROCEDURE

• In addition, three tests of visual receptors and their responses were conducted:–visual pursuit of a moving object: the kitten was

shown the experimenter’s hand moving slowly in front of it. The movement of the kitten’s eyes was recorded. A kitten with normal visual experience follows the movement with its eyes.

–pupillary reflex to light: a flashlight was moved across the eye and the change in pupil size was noted. The pupil of a kitten with normal visual experience shrinks in response.

–tactual placing response: the kitten was held as in the paw placement test but its front paws were put against the vertical surface of the table. A kitten with normal visual experience responds by moving its paws to the horizontal surface.

RESULTS• After periods of exposure – A successfully demonstrated visually

guided paw placement while every P mate failed to display the response.

• Observations suggest the placing response developed in the livelier of the A subjects with fewer hours of exposure than the quieter ones

• The blink response developed at the same time as the placing response.

• On the same day as each kitten A demonstrated the visually-guided paw placement response, the pair was tested on the visual cliff (and the next day). The results of these tests are shown in Table 1. They show that all of the active kittens had normal responses to depth but the passive kittens were crossing to the shallow or deep side at random. This suggests that they were unable to discriminate between the deep and shallow drops.

• Observations of the P group, after their prolonged passive exposure, showed they failed to perform visual paw placement.

• After the 48 hours in the illuminated room, P were retested and displayed normal visually-guided paw-placements and performed all descents to the shallow side of the cliff.

RESULTS

• The findings support the hypothesis that self-produced movement and concurrent visual feedback are essential for the development of visually-guided behaviour.

• According to Held and Hein, only the self-moving kitten developed the normal visual perception. The other one, which was deprived of self-actuated movement, could not develop the depth perception.

Results

• One of the main findings of the study is all of the active kittens developed a normal visually-guided paw placement response when they had spent 3 hours or less in the apparatus. No passive kitten had acquired a visually-guided paw placement. Also, all of the active kittens had normal blink responses and normal responses to the visual cliff (though the passive kittens were crossing to the shallow or deep side at random. Overall, the findings fit the idea that self-produced movement and concurrent visual feedback are better for the development of visually-guided behavior.

Discussion / Evaluation

• Held & Hein observe that there are possible alternative explanations for their findings. One is that the deprivation could have led to some anatomical or physiological loss (atrophy) which was causing the passive kitten’s perceptual deficits. This is unlikely, however, as they showed normal physiological responses (in the three additional tests). Furthermore, it would be unlikely that such a minimal recovery time for the sub-group of passive kittens could overcome any such damage. They also discount the possibility that the problems are purely physical or behavioural – since the kittens could perform the tactual placing response normally.

• Another criticism suggests that the differences could have been due to emotional responses caused by the release from deprivation during testing. However, Held & Hein suggest that this cannot be the case because the restriction of the P and A kittens was so similar. Furthermore, there was no apparent difference between the P and A kittens in terms of their fear or excitement in response to the novel situations.

Questions for Consideration

Consider this experiment in terms of ethical guidelines for the use of animals in research. Identify two ways in which the animals experienced conditions which raise ethical issues and two ways in which the animals were well cared for.

Reflective

• AICE Roulette! You know the drill