Perception
PERTEMUAN 2
2.1 The biological bases of
perception
• The process of perception
– Perception is the process by which we make
sense of our surroundings by interpreting the
information from our sense organs.
• The visual system
• Damage to the visual pathway
• Primary visual processing
– orientation columns
Spatial frequency analysis
• Spatial frequency refers to the alternation
of patterns of light and dark in a visual
stimulus.
2.2 Psychological approaches to
visual perception
• The Gestalt approach
• Top-down and bottom-up processing
• Perceptual constancy
– our perceptions of the world remain
reasonably stable despite a continuously
changing stimulus environment.
The Gestalt approach
Top-down and bottom-up
processing
• Bottom-up
– automatic, fast, rigid
– e.g. template and distinctive feature models
• Top-down
– slower, flexible, influenced by experience and
expectations (set, schemas)
– e.g. ambiguous figures, scene perception
– context effects
Depth perception
2.3 Visual illusions
• Theoretical explanations of illusions
• Top-down, bottom-up, side-ways rules
or physiological fatigue?
– Gregory (1996) suggests that visual illusions
usually fall into one of four main categories
(a) Muller-Lyer illusion;
(b) Ponzo illusion
2.4 Marr’s theory
• The primal sketch
• The two-and-a-half-dimensional
representation and the threedimensional model
Ellis and Young’s (1996) adaptation of the stages
in Marr’s model for application to disorders of
perception or attention
2.5 Object recognition processes
• Templates
– the recognition of an object involves the
matching of a pattern of stimulation to a
stored representation of that object
• Prototypes
– averaging over the family of instances of the
object that has been actually encountered and
from which a certain amount of deviation is
possible
Feature analysis
• Neisser (1964, 1967), visual search
experiments.
– investigate the considerable variation in the
ease with which we can identify a given object
amongst a field of distractors.
Pandemonium
2.6 Sound Perception
• pitch perception
• loudnes perception
• sound localization