Sense and Perc Exam One

Perception

The means by which we gain knowledge about what is in the world around us; information gets from the world to the perceiver.

Prospective control

The fundamental/primary purpose of perception; using information about the environment to control future actions.

Prospective

Relating to or affecting the future.

Fundamental problem of perception

How information crosses the gap between an object in the world and the animal perceiving it.

Action at a distance

The idea that one object affects another without physically contacting it; perception theories cannot rely on this explanation.

Animal

In Aristotle's theory, the organism doing the perceiving.

Object

In Aristotle's theory, the thing being perceived.

Medium

In Aristotle's theory, something between the animal and object that conveys information.

Principle of representation

The idea that perception involves copies or representations of things in the head.

Intromission

The idea that copies/information travel from the world into the perceiver, such as light entering the eye.

Emanation

The idea that perceptual energy originates from the perceiver and travels outward.

Pointillistic theory of emanation

An early medieval concept of visual perception was proposed by the Arab philosopher and scientist Al-Kindi (Alkindi) around 850 AD. It represents a crucial stepping stone in the history of optics, bridging ancient Greek philosophy with modern theories of vision

Alhazan

An early thinker who treated the eye as an optical instrument and explained vision using light energy rather than spiritual energy.

Structured light

Light that carries information about the environment because surfaces selectively absorb, reflect, and scatter it.

Pointillism

The idea that pencils/rays of light create a mosaic of points in the eye.

Kepler

A thinker who explained how a lens focuses light into an image on the retina and emphasized destructive mapping.

Retina

The sensitive part of the eye upon which images are formed.

Camera obscura

An optical system demonstrating how an image of the outside world can be formed, similar to how the eye works.

Destructive mapping

The mapping from the world to the sensory system in which important information is lost.

Distal stimulus

The actual object or event in the world being perceived.

Proximal stimulus

The image/information that reaches the sensory system from the distal stimulus.

Example of destructive mapping

A real leaf is the distal stimulus; the inverted, distorted 2D retinal image is the proximal stimulus.

Why is the proximal stimulus ambiguous?

The same distal object can produce many different proximal stimuli, and different distal objects can produce the same proximal stimulus.

Enrichment

The idea that something must be added to sensation in order to form perception.

Sensation

Raw information coming into the sensory system.

Perception vs. sensation

Sensation is raw sensory information; perception is the representation created after mental processing/enrichment.

2D

to

Bottom

up processing

Top

down processing

Ontology

Theories about what exists.

Materialism

A monist view that only the physical world exists and humans are physical machines.

Mind

matter dualism

Epistemology

Theories about how things can be known.

Nativism

The idea that knowledge is inherited from one generation to the next; nature.

Empiricism

The idea that knowledge is learned through observation and experience; nurture.

Rationalism

The idea that knowledge comes through reason and that we create knowledge about the world through reasoning.

Rene Descartes

A thinker associated with mind

Mind

body dualism

Indirect perception

The idea that perception of the outside world is indirect because we are aware of sensory/nervous system states rather than directly experiencing objects themselves.

Johannes Muller

A thinker associated with the theory of specific nerve energies.

Theory of specific nerve energies

The quality of a sensation depends on which particular nerves are stimulated.

Specific nerve energies example

Stimulating visual nerves can produce an experience of light even without actual light entering the eye.

John Locke

An empiricist who argued that people are born without ideas and gain knowledge through experience.

Primary qualities

Qualities that exist in the world independently of a perceiver.

Secondary qualities

Qualities imposed by the perceiver and existing only in the head.

George Berkeley

An empiricist who argued that perceivers cannot reliably distinguish primary and secondary qualities.

Cue

A clue used to construct a representation of the world; cues can acquire meaning through associations.

Historical legacy of perception theories

Dualism, representation/copies, destructive mapping, enrichment, cue theory, and indirect perception.

Light

Electromagnetic energy used for vision and photosynthesis.

Amplitude of light

Determines light intensity/brightness; greater amplitude means brighter light.

Wavelength of light

Related to the color of light; short wavelengths are associated with blue and long wavelengths with red.

Radiant light

Direct light from a light source; relatively unstructured and carries little information about objects.

Ambient light

Light after it has interacted with surfaces; structured light that carries information about the environment.

Why is light useful for vision?

It travels in straight lines, is selectively absorbed/reflected, can be refracted/focused, and reaches the eye almost instantly.

Pupil

The opening in the eye that allows light to enter.

Depth of field

The range of distances over which an image is focused.

Small pupil effect

A small pupil allows less light in but produces a greater depth of field, so more distances are in focus.

Large pupil effect

A large pupil allows more light in but produces a smaller depth of field.

Accommodation

Changing the shape of the lens to change the amount of refraction and focus an image.

Emmetropia

Normal vision.

Myopia

Near

Hyperopia

Far

Astigmatism

A vision problem associated with an irregular/football

Sensory transduction

The transformation of energy in the environment into energy in the nervous system.

General transduction pathway

Environmental stimulus → receptor → electrical signal → nerve fiber/axon → synapse → nervous system.

Photoreceptor

A retinal receptor containing photopigment that absorbs light and helps transform it into neural energy.

Photopigment

A light

Rods

Photoreceptors specialized for dim light; highly sensitive and involved in motion detection.

Cones

Photoreceptors specialized for bright light, color, and sharp visual detail.

Fovea

The central retinal region where cones are concentrated; provides high visual acuity/detail.

Blind spot

A region of the retina with no photoreceptors, located about 20 degrees to the side of the fovea.

Rods/cones → bipolar cells → ganglion cells → brain.

Retinal pathway

Bipolar cells

Retinal cells that provide an intermediate pathway between photoreceptors and ganglion cells.

Ganglion cells

Retinal cells whose axons carry visual information toward the brain.

Neural convergence

The process in which many receptors send signals to fewer ganglion cells.

Rod convergence

Rods have greater neural convergence, allowing weak signals to be combined and increasing sensitivity but reducing detail.

Cone convergence

Cones have less convergence, allowing more individual information and greater visual resolution.

Visual sensitivity

Rods provide greater sensitivity, especially in dim light.

Visual acuity

Ability to resolve fine detail; cones provide greater acuity.

Adaptation

A change in sensory sensitivity over time, often involving a decrease in sensitivity or calibration.

Dark adaptation

An increase in sensitivity when entering darkness.

Dark adaptation relationship

As sensitivity increases, the sensory threshold decreases.

Threshold

The level of stimulation needed for a sensory system to detect a stimulus.

Calibration

The process of keeping sensory, perceptual, and motor systems accurate.

Prism adaptation

An example of calibration in which feedback allows the perceptual and motor system to adjust to distorted visual input.

Sensory coding

The way information is represented through patterns of neural firing.

Intensity coding

Intensity is coded by the frequency of neural firing.

Quality coding

Quality is coded by which nerves/receptors are active.

Taste

The sensory system that helps motivate organisms to eat useful substances and avoid harmful ones.

Sweet taste

Associated with energy and generally perceived as pleasant.

Salty taste

Associated with necessary minerals and generally perceived as pleasant.

Sour taste

Associated with possible food decay and generally perceived as unpleasant.

Bitter taste

Associated with possible toxins and generally perceived as unpleasant.

Umami taste

Associated with nutrition and generally perceived as pleasant.

Qualitative coding for taste

The active receptor/nerve provides information about the quality of the taste.

Smell

The sensory system that detects chemical information through the nose.

Flavor

The combination of taste and smell.

Why does food taste different when you cannot smell?

Flavor depends on both taste and smell, so reducing smell information changes the overall flavor experience.

Newton's color experiment

Newton used prisms to separate light into individual colors and found that a second prism did not split the colors further.

Color circle

A representation showing how the brain processes colors in a circular relationship rather than simply as a linear physical continuum.