Basic Psychology- Perception Flashcards
When perceiving an object it needs to be differentiated from its background. Determinants of figure vs.
ground differentiation are?
4
- Contour –surroundedness
- Size
- Orientation
- Symmetry
This is also influenced by perceptual set
What does rubins vase illusion demonstrate?
What is the implication of this?
Reversal of figure-ground perception frequently occurs so that sometimes, the ground is perceived as
figure and vice versa e.g. try googling for images of Rubin’s vase illusion. This indicates that same stimuli
can produce more than one perception.
What 2 cues does depth perception depend on?
Pictorial and non-pictorial.
Non pictorial cues for depth perception.
Tend to be binocular.
a. Retinal image disparity
b. Stereopsis
c. Accommodation (monocular)
d. Convergence
Pictoral Cues for depth perception.
Pictorial cues (secondary) include largely monocular elements such as
a. Size
b. Brightness
c. Superimposition
d. Texture
e. Linear perspective (rails converge at distance, wide apart when closer)
f. Aerial perspective (colour – blue mountains means a distant sight)
g. Motion parallax (closer it is faster it seems)
At what age to children perceive depth?
What is the experiment called?
Visual cliff is an apparatus used to test an infant’s perception of depth. A pane of thick glass covers a
shallow drop and a deep drop. The underlying surfaces of both deep and shallow sides are covered with
the same chequered pattern. Children of six months and older will not venture to the ‘deep side’ and this
is taken as an indication that the child can perceive depth.
Perceptual constancy is defined as the ability to perceive objects to be the same and unchanging in
character despite varied inputs. It consists of:
4
- Size constancy
- Shape constancy e.g. a door is always a door no matter which angle it is showing to the viewer
- Location constancy – movement of the head gets nullified somehow so we do not perceive
objects around us getting relocated as we move our head! - Brightness, hue and colour constancy
Autokinesis- what phenomenon could this explain?
Phi phenomenon- what illusion is this?
Autokinesis refers to the phenomenon that if light is shown from a small, dim, and fixed light source for
an extended period of time in a dark room, it will appear as if the light source is moving. This visual
illusion can explain UFO sightings and can also affect pilots.
The phi phenomenon is a perceptual illusion described by Wertheimer. This refers to the phenomenon in
which a false perception of motion is produced by a succession of still images shown with fixed time
interval rapidly
Bottom Up theory of perception
Bottom-up theory: Gestalt is an example of a bottom-up theory. According to bottom up theories,
perception is purely data driven and directly starts with the optic array. Piecing together of basic elements
of the data gives rise to more complex systems. This makes the original elements sub-systems of the
‘emergent system’. But perception is not just seeing, it is ‘seeing as’.
Top down theory of perception
Top-down theory: Gregory’s constructivist theory is an example of a top-down theory. According to this
theory, retinal images are sketchy and cannot explain the complex and fully formed perceptions that we
experience. Perception is best defined as a process of using information known already to formulate and
test a hypothesis. It is driven from the ‘top down’ – i.e. from higher cortical areas. Illusions such as Muller
Lyer (i.e. when you compare >—-< and , despite the horizontal line being of same length in both
instances, the first one may appear to be longer) support top-down processing.
Perceptual set
A perceptual set is defined as the readiness to perceive selected features as an object. This is related to the
level of motivation e.g. hunger, emotional state, values, beliefs, context and expectations (e.g. UFOs are
sighted only by those who believes in them and ‘expects’ them)
Illusions
Hallucinations
Illusions and hallucinations
Illusion is defined as any perceptual situation in which a physical object is perceived but appears different
from what it really is e.g. a white wall appears yellow if a yellow light is shone on it.
A hallucination is an experience in which an object (e.g. sound or light) is perceived in the absence of any
corresponding object in the real world. A hallucination is often indistinguishable from genuine perception.
At what age can we discriminate brightness and carry out eye tracking?
From birth we have the ability to discriminate brightness and carry out eye tracking, visual acuity is
significantly impaired and focusing is fixed at 20cm.
What perception do we develop at 2-4 months?
Depth (visual cliff)
At what age to we develop accomodation and which visual skill?
By 4 months – accommodation and colour vision seems to be
present in most children.
