Introduction to Psychology - Perception and attention

What is sensation?

Receiving, translating, and transmitting message from the outside world to the brain

...like seeing flashes of light and dark on screen!

What is perception?

Organizing and interpreting information that is received from the outside world

...like reading and making sense of the words on the screen!

Sensation versus Perception

Sensation: info received by your brain

Perception: info organized and interpreted by your brain

2 types of perceptual processing

bottom-up; top-down

Bottom-up processes

driven by sensory information and general knowledge

No expectations

Top-down processes

- driven by knowledge, experience, and expectations

Expectations influence perception

Bottom-up versus Top-down processing

Bottom-up: guided by sensory input and general knowledge to make sense of things

Top-down: expectations influence perception

Cocktail Party Effect

You are at a party deeply engaged in conversation with a friend - lots of people around you and lots of noise that you are oblivious to

Over the noise, you suddenly hear someone behind you say your name. You had no idea what anyone else was saying, how did you notice your name??

Selection!

Early Selection Model

Assess physical characteristics to select what info to process (tone-deeper or higher pitched, direction-left or right ear)

Problems with early selection

Cocktail party effect - can hear your own name even though conversation is unattended

Shadowing task (listen to one message while ignoring other) - ppl can do the task successfully even when both messages came from the same voice in the same ear

Late selection model

Selection based on meaning

Selection happens at short-term memory stage

Problems with late selection

predicts that we should be able to make simple response about unattended info, but we cannot

Dichotic listening results

People can detect VERY LITTLE from unattended message

can tell - if voice or noise, if man or woman

cannot tell - if foreign language or not, if repeat just few words over and over

Attenuation Model

information in unattended channel is weakened early, but not completely filtered out

- can attend as much as one needs to select
-Sensitive to experience and goals

Multimodal Model

filter applied early OR late depending on the task and circumstances

Early - easier, less effort

Late-more effort

Divided attention

2 sources of info, want to respond to both at the same time (video game and conversation)

Performance on task declines (slower, more errors) when we divide our attention between tasks (like driving while talking on the phone)

Dual Task Paradigm Study

Present two tasks and compare the speed and accuracy of dual performance vs doing each task alone

Results: slows reaction!

Capacity Theory

tasks require mental effort or cognitive resources
- harder tasks require more cognitive resources
- resources are limited, you control allocation of resources

If tasks require more resources than available, you will see a cost in performance

Stroop Effect

difficult to focus attention on color and suppress reading