Psychology 001Introduction to Psychology

Christopher Gade, PhDOffice: 621 Heafey

Office hours: F 3-6 and by apt. Email: gadecj@gmail.com

Class WF 7:00-8:30 Heafey 650

Sensation and Perception Sensation: the conversion of energy from

the environment into a pattern of responses by that nervous system.

Perception: the interpretation of that information.

In order to understand our perception of information, we first need to understand how we are sensing that information.

What Exactly Do We See? Light is composed of

pulses of electromagnetic energy that vary in both wavelength and amplitude.

The amplitude of the electromagnetic wave is what determines the intensity (brightness) of the light.

What Exactly Do We See (cont.)?

The wavelength (i.e. frequency) of the light pulse is what determines the hue (color) of the light wave.

• Humans are able to see light on a range of 400 to 700 nanometers (nm). Other animals have sensitivity at different wavelength ranges.

The Path of Vision (After the Eye)

And… The fact that many of our areas are

arranged very intricately• Layering and columns (related to brain

structures and the paths to those structures)• Specialization of

function Location receptors Orientation receptors Ocular information

receptors Color receptors

Color SensationThe Young-Helmholtz/trichromatic theory.

• Proposes that our receptors respond to three primary colors: blue, green and red.

• “Color vision depends on the relative rate of response by the three types of cones.”, I.e. the combination of different levels of firing in each type of cone gives rise to the broad spectrum of colors perceived.

Visual SensationColor: • What about yellow, white, and black?• What about negative afterimages?

“ON” “OFF”red greengreen red blue yellow yellow blue black whitewhite black

The Opponent Process Theory:• We sense color not in terms of

separate categories but rather in a system of paired opposites: red vs. green, blue vs. yellow and black vs. white.

The Interpretation of Colors and Patterns The Brightness Contrast

• Method of determining the colors of objects (going beyond just the frequency of the electromagnetic waves).

• The brightness of surrounding objects influences our perception of the color and brightness of an object.

Visual SensationThe Retinex Theory:

• The Cerebral Cortex also plays a role in how we experience color, I.e. color constancy, by comparing different patterns of light from different areas of the retina.

Perception and Gestalt Psychology Knowing the visual

system is great if we want to know about the basics of vision.

But what about interpretation? How do we make sense of ambiguous stimuli?

Gestalt and perception psychology address this problem.

Gestalt Psychology (cont.) Gestalt psychology is

a field that focuses on our ability to perceive overall patterns.

“The whole is different (and often greater) than the sum of its parts”.

Our perception is based on our attempts to create semblance out of the mess of stimuli that we are presented with.

Tricks to Determining Distance/Depth

Binocular Cues (two eyes)

• Retinal disparity: the position of an object is determined by the different signals received by the two eyes.

• Convergence: the distance of an object is determined by the amount of eye movement required to focus on an object.

Monocular Cues (two eyes are not required)

Object size (relative size): nearer objects look bigger.

Accommodation: Our brains can detect how much the lens of the eye needed to shift in order to focus on an object.

Detail (relative clarity): more detail signifies a closer object.

Visual Illusions So we interpret stimuli in our world

to make sense of it… great. Is there any situations where this comes at a cost?

Most of the time, this translation of information is very useful for our interaction with the real world.

But sometimes, there are situations that trick the mind.

The Muller-Lyer Illusion

Depth Perception Illusions

The Ponso Illusion

The Moon

Illusion

The Ames Room