Sensation and Perception Chapter 3

In the early stages of _______, peripheral rod receptors are destroyed leading to poorer peripheral vision.

retinitis pigmentosa

Our perception of the environment depends on

both the properties of the environmental objects and properties of the electrical signals in the nervous system.

Converging circuits with excitation and inhibition are associated most closely with which step of the perceptual process?

neural processing

The visual pigment molecules are contained in the

outer segments of the visual receptors.

The isomerization of a single pigment molecule triggers what is best described as a

chain reaction

Jan tries to focus on the tip of her pencil as she brings it closer to her. She feels the strain on her eye as she does this. What she is feeling in her eye is due to the process called

Accommodation

Nina does a demonstration of "seeing" the blind spot, in which a grid pattern surrounds the black dot that disappears when it falls on the blind spot. What does Nina most likely see in the area where the dot disappears?

a continuation of the grid pattern

To isolate the rod portion of the dark adaptation curve, researchers

use rod monochromats as the participants

Light can be described in terms of wavelength, or as consisting of small packets of energy called

Photons

Acuity develops to almost 20/20 vision by the time the infant is

One year old

Convergence results in _________ sensitivity and _______ acuity.

increased; decreased

Purkinje shift

is when reds appear brighter than blues in well-lit conditions, but blues appear brighter than reds in dim conditions.

The "rod-cone break" in the dark adaptation curve occurs after about ___ in the dark.

7 minutes

The distance at which the lens can no longer bring a close object into focus is called the

near point

Reading the eye chart in an optometrist's office is used to measure

acuity

The stimuli used in the preferential looking technique of testing infant acuity are

gratings

LASIK surgery is used to treat _______ by cutting a small flap in the _________.

myopia; cornea

A retinal condition that destroys the cones in the fovea is

macular degeneration

A wavelength of 100 nm would fall in the ______ range of the electromagnetic spectrum.

ultraviolet rays

The blind spot is located

where the optic nerve leaves the eye

Rods and cones synapse with ______ cells, which then synapse with ____ cells.

bipolar; ganglion

Vera has hyperopia, and tends to get headaches when she reads. This is because

Vera also has presbyopia and has the constant need to accommodate.

_______ reacts to light to start the process of transduction.

retinal

There are ____different cone receptors, each with different absorption spectra.

3

Which of the following is true about the difference between the rods and the cones?

There are about 120 million rods in the human eye and about 5 million cones.

Rushton demonstrated that the physiological mechanism behind dark adaptation is

visual pigment regeneration.

The peak in the spectral sensitivity curve is about _____ for the rods, and about _____ for the cones.

500 nm; 560 nm

Acuity is better in the ____ than in the _____.

fovea; periphery

The episode of "Mythbusters" cited in the textbook demonstrated that dark adaptation was the reason why

pirates wore eyepatches.

Visible light is between _____ and ____ nm within the electromagnetic spectrum.

400; 700

Our perception of the environment begins with _____.

the distal stimulus

A wavelength of 10,000 meters would fall in the _____ range of the electromagnetic spectrum.

radio wave

The electromagnetic spectrum is a continuum of electromagnetic energy that is produced by _____ and is radiated as

_____.

electric charges; waves

The structure of the eye that provides about 80% of the eye's focusing power is the _____.

cornea

Jan tries to focus on the tip of her pencil as she brings it closer to her. She feels the strain on her eye as she does this.

What she is feeling in her eye is due to the process called _____.

accommodation

The ciliary muscles change the shape of the _____, providing about 20% of the eye's focusing power.

lens

Lorelei's mother is 60 years old, and, because of the condition called _____, she has a difficult time bringing near

objects into focus.

presbyopia

In _____, the eyeball is too long, resulting in difficulty seeing far objects.

axial myopia

Individuals with myopia may have difficulty seeing _____ objects clearly. Often times, they are also referred to as

being _____.

distant; nearsighted

The visual pigment molecules are contained in the _____.

outer segments of the visual receptors

The isomerization of a single pigment molecule triggers what is best described as a _____.

chain reaction

The blind spot is located _____.

where the optic nerve leaves the eye

Nina does a demonstration of "seeing" the blind spot, in which a grid pattern surrounds the black dot that disappears

when it falls on the blind spot. What does Nina most likely see in the area where the dot disappears?

a continuation of the grid pattern

To isolate the rod portion of the dark adaptation curve, researchers _____.

use rod monochromats as the participants

The "rod-cone break" in the dark adaptation curve occurs after about _____ in the dark.

7 minutes

When visual pigments become bleached they are _____.

detached from the opsin

Rushton demonstrated that the physiological mechanism behind dark adaptation is _____.

visual pigment regeneration

Cone spectral sensitivity is measured by having the observer _____.

look directly into a light

The three major parts of a neuron are _____.

dendrites, cell body, axon

The difference in charge between the inside and the outside of the nerve fiber when the nerve is at rest is _____ mV.

-70

Which of the following statements best defines the "propagated response"?

Once a response is triggered, the response travels the length of the axon without decreasing in amplitude

As stimulus intensity is increased, recording from a single neuron shows that _____.

the rate of firing of the nerve fiber increases

The upper limit of a neuron's firing rate is estimated to be _____ impulses per second.

800

At the beginning of the action potential, _____ ions flow from outside the nerve fiber into the nerve fiber.

positive sodium

The flow of ions that create the action potential are caused by the changes in the _____ of the nerve fiber.

permeability

Synaptic vesicles contain chemicals called _____ that are released across the synapse to the next neuron.

neurotransmitters

The _____ analogy is used to describe the relationship of neurotransmitters with receptor sites.

"lock and key"

______ is the process by which inhibitory transmitters cause the inside of the neuron to become more negative.

Hyperpolarization

The rate of firing of the postsynaptic neuron depends on the amount of _____ input it receives from the presynaptic

neuron.

excitation and inhibition

_____ is necessary for the neural transmission and processing of information.

inhibition and excitation

Rods and cones synapse with _____ cells, which then synapse with ____ cells.

bipolar; ganglion

Converging circuits with excitation and inhibition are associated most closely with which step of the perceptual

process?

neural processing

If we compare how the rods and cones converge onto other retinal neurons, we find that _____.

rods converge more than foveal cones

Convergence results in _____ sensitivity and _____ acuity.

increased; decreased

Acuity is better in the _____ than in the _____.

fovea; periphery

The difficulty of reading under dim light conditions can be explained by _____.

the fact that rod functioning predominates during dark adaptation, resulting in poor acuity

The stimuli used in the preferential looking technique of testing infant acuity are _____.

gratings

Which of the following is a reason for the poor acuity of newborns?

The visual cortex of the newborn is only partially developed.