Sensation and PerceptionThe Basics of Signal Perception

Vision

http://youtube.com/v/0cVlTeIATBs

1. Sensory Reception

2. Sensory Transduction

3. Action Potentials4. Brain Processing

Sensory Reception

Sensory Transduction

StimulusReceptors

TranslationCell Body

Ah Hah!

Resulting Action Potentials

Transduced signals are sent to the brain

Brain Processing

The minimum stimulus needed for the receptor to detect 50% of the time

Absolute Threshold

This is different for each individual

Absolute Threshold

Which helps explain things like pain tolerance

Absolute Threshold

Difference Threshold

The minimum difference in stimulus intensity required for us to feel a difference.

Difference Threshold

As the stimulus increases, so does the DT

Signal Detection Theory

The fly in the ointment

We judge stimulus in order to decide whether to attend or not

We need to filter out all the craziness to focus

http://youtube.com/v/cAwUUgnBhCU

The Rods and Cones are the Transducers

Cones:

Bright VisionMany more

Packed in the center of the fovea

Rods

Dark VisionFar fewer

Night visionShades of gray

Poor detail

Night Driving:

Mostly Rods

Reflectives activate the Cones

Color Perception

Color = Wavelengths

Brightness = Amplitude

Visual Perception

Figure and Ground

Grouping

Closure and

Contours

Grouping

Proximity

Bottom-Up Processing

From sensory input to processing:

We judge what we see based on processing AFTER input

Top-Down Processing

Our pre-judgements affect what we really see

Some optical illusions

http://www.buzzfeed.com/jessicamisener/crazy-optical-illusions#2cpkulg