Cognition DISCUSSION 3
Introduction To Perception
Learning objectives: By the end of this presentation you will be able to…
describe the role of bottom-up (sensation) and top-down processes in perception; explain how “perception makes sense of sensory information.”
identify problems that perception must overcome and give examples; recognize these as part of the more general problems of cognition.
By describing top-down processes that make sense of bottom-up (sensory) information, explain the perception of 1) objects, 2) speech and 3) pain
I. Bottom-Up (Sensory) & Top-Down Processes in Perception
EXPERIENCE
PERCEPTION
SENSATION
Bottom-up process whereby
sensory receptors receive
stimulus energy, convert
that energy into neural impulses, and deliver that information to higher levels of mental processing for integration
Top-down process whereby higher-level mental processes
organize and interpret sensory
information; the “mental glue”
that “makes sense” of sensory
information.
Introduction To Perception
Introduction To Perception
II. Problems For Perception
the problems for perception are the problems for cognition generally, that the environment is ambiguous.
example 1: inverse projection problem…
inverse projection problem -problem (faced by the mind) of working backwards from the retinal image to determine the shape of the originating object.
Introduction To Perception
II. Problems For Perception
the problems for perception are the problems for cognition generally, that the environment is ambiguous.
example 1: inverse projection problem…
example 2: incomplete information…
Whose face is this?
Can’t tell? Try looking obliquely; try squinting.
Why would squinting improve recognition? Squinting reduces sensory information.
Reducing sensory information allows perception to play a greater role making sense of sensory information.
Introduction To Perception
II. Problems For Perception
the problems for perception are the problems for cognition generally, that the environment is ambiguous.
example 1: inverse projection problem…
example 2: incomplete information…
Introduction To Perception
III. Examples of Perception At Work
note: look for how top-down processes make sense of bottom-up (sensory) information
A. Object Perception
Can you identify the objects in the following photgraphs?
Caption: “Multiple personalities of a blob.” What we expect to see in different contexts influences our interpretation of the identity of the “blob” inside the circles.
Introduction To Perception
III. Examples of Perception At Work
note: look for how top-down processes make sense of bottom-up (sensory) information
A. Object Perception
B. Speech Perception
Introduction To Perception
speech segmentation- ability to tell where one word ends and another begins even when there is no physical segmentation in the sound energy, as in…
segmentation is dependent on “top-down” interpretation of language (we cannot segment speech in a foreign language)
Introduction To Perception
III. Examples of Perception At Work
note: look for how top-down processes make sense of bottom-up (sensory) information
A. Object Perception
B. Speech Perception
C. Perception of Pain
placebo effect- the decrease in pain from a substance that has no pharmaceutical effect. Due to expectation that the substance will reduce pain.
pain resides in the brain; so does the placebo effect…
Introduction To Perception
Review: For each, what is the top-down process that makes sense of bottom-up (sensory) information?
A. Object Perception: Personalities of a Blob?
context influenced the interpretation of a blob
B. Speech Perception: Speech Segmentation
language enabled speech segmentation
C. Perception of Pain: Placebo effect
expectations of relief caused placebo effect