cognitive psychology 2

What are the three functions of hearing?

1) Communication between people. 2) Signalling and alarm (warning of danger). 3) Object recognition and localization, like vision.

How is a sound wave created, physically?

An object vibrates. The vibration needs something to travel through (a medium). In air it moves at about 340 m/s. In water it moves at about 1500 m/s.

What is a sound wave?

Sound traveling through air as air particles are pushed together (compression) and pulled apart (rarefaction).

What is an oscillogram?

A graph that shows air pressure over time.

Which wave property gives loudness?

Amplitude. This is how big the pressure changes are.

Which wave property gives pitch?

Frequency. This is how many cycles happen in one second.

What is phase?

How much of a full cycle has already passed, compared to a starting point.

What is loudness based on, and how do we measure it?

It is based on the amplitude of the wave. We measure it in decibels (dB).

What do 0 dB and about 130 dB mean

0 dB is the quietest sound we can just hear (absolute threshold). About 130 dB is where sound starts to hurt (pain threshold).

At which frequency do we hear best?

Around 1000 Hz. How sensitive we are depends on frequency.

What happens if a sound stays the same for a long time?

It seems quieter. Our hearing adapts.

Is loudness the same as physical intensity?

No. Loudness is a judgment of our brain. It depends on frequency and on the situation.

What is pitch based on? What can humans hear?

Frequency (Hz). Humans hear about 20 to 20,000 Hz.

What is temporal theory (Rutherford, 1886)?

The basilar membrane vibrates at the same speed as the sound. The firing rate of the nerves shows the pitch.

Why does temporal theory not work for high sounds?

Above about 1000 Hz, neurons cannot fire fast enough.

What is place theory (Helmholtz)?

Different places on the basilar membrane react most to different frequencies.

What did Békésy (Nobel Prize, 1961) find?

The whole membrane moves, like a shaken bedsheet. But the place with the biggest movement changes with frequency. This improved place theory.

Simple pitch or complex pitch?

Simple pitch is one single frequency. Complex pitch is a basic frequency (fundamental) plus extra frequencies (overtones). This is connected to timbre.

What is timbre?

The quality that makes two sounds different when they have the same pitch and loudness, for example a piano and a violin playing the same note.

What causes timbre?

The pattern of overtones on top of the fundamental frequency.

What is a simple tone?

A sound with only one frequency. The slide says a perfect simple tone does not really exist.

What is a complex tone?

A sound with a fundamental frequency and overtones. Fourier analysis can split it into its parts.

What is white noise?

A sound with all frequencies together. You hear it between radio stations.

What is the interaural intensity difference?

The head makes a “sound shadow.” A sound from the right is quieter in the left ear.

What is the interaural time difference?

A sound from the right reaches the right ear a tiny moment before the left ear.

How does the brain find the direction of a sound with two ears?

It uses both cues together: the difference in loudness and the difference in time.

What is pinna spectral filtering?

The folds of the outer ear reflect sound. This changes the sound in a way that shows the height (elevation) of the source.

What is the cone of confusion?

The places where two-ear cues do not help, for example front vs. back and up vs. down. One-ear (pinna) cues solve this problem.

Which cues show how far away a sound is?

The sound gets quieter with distance. Also, the mix of direct sound and echo (reverberation) changes.

Is touch one sense?

No. There are at least three skin senses: pressure, temperature and pain.

What is the stimulus for pressure? Where are we most sensitive?

The stimulus is physical force on the skin. Lips, nose and cheek are the most sensitive. The big toe is the least sensitive. In sensitive places we can feel 5 milligrams.

How do temperature receptors work?

Cold receptors react when the skin gets colder. Warm receptors react when the skin gets warmer. Both are just under the skin.

Why does a swimming pool feel cold first and then normal?

Adaptation. Pressure and temperature senses adapt a lot.

Why can very hot things feel cold for a moment?

Very hot things activate warm and cold receptors at the same time.

What is active touch?

Touching and exploring an object on purpose. It uses the motor senses too. Example: finding keys or coins in your pocket without looking.

Meissner’s corpuscles?

Detect light touch and texture. Adapt fast. Small receptive field.

Pacinian corpuscles?

Detect deep pressure and vibration. Adapt fast. Large receptive field.

Merkel’s discs?

Detect steady pressure and fine detail or edges. Adapt slowly. Small receptive field.

Ruffini endings?

Detect skin stretch and joint position. Adapt slowly. Large receptive field.

Free nerve endings?

Detect pain and temperature.

What is the difference between fast and slow adapting receptors?

Fast adapting receptors detect change (start, stop, vibration). Slow adapting receptors detect a steady state (constant pressure, shape).

Which receptors sense what is happening inside the body?

Baroreceptors (pressure), chemoreceptors (chemicals) and mechanoreceptors (movement or stretch) in the organs.

How do signals from the organs reach the brain?

Through cranial nerve X (the vagus nerve) and through the spinal cord. They go straight to the insular cortex.

What do these signals influence?

Hunger, nausea, body arousal, and Damasio’s gut-feeling decisions (somatic markers and emotion).

What are kinesthetic receptors (proprioception)?

Muscle spindles, Golgi tendon organs and joint receptors. They tell the brain where your arms and legs are.

What does the vestibular system do?

Semicircular canals sense turning (rotation). Otolith organs sense gravity and speeding up or slowing down (acceleration).

What are efference copy and corollary discharge?

The brain’s way to know if a movement came from you or from the outside world.

What can cause pain?

Any strong stimulus that can damage the body: pressure, heat, electric shock or chemicals.

What is the difference between phasic and tonic pain?

Phasic pain is sharp, fast and short (the first jolt of a twisted ankle). Tonic pain is dull and lasts long (the throbbing swelling later). They use different nerve pathways and different brain areas.

What is gate control theory (Melzack & Wall)?

To feel pain you need two things: active pain receptors and an open “gate” in the spinal cord. The brain (attention, expectation, culture) can close the gate.

What does gate control theory explain?

Why rubbing a sore place, acupuncture or a special mental state (for example a ritual trance) can reduce pain a lot, even when the damage is the same.

What is the main message about pain?

Pain comes from the mind as much as from the receptors. The same injury can hurt differently depending on attention, expectation and culture (example: the Indian hook-swinging ceremony).

Why is smell called the most primitive sense?

Smell receptors in the nose connect to the brain with no synapse in between. It is the most direct route to the brain of all senses.

How are smell receptors different from eyes and ears?

They are open to the environment. Nothing protects them, unlike the cornea of the eye or the outer and middle ear.

How many types of smell receptors do we have? How many smells can we tell apart?

About 1,000 types of receptors. We can tell apart 10,000 to 40,000 smells.

Where are the taste receptors? What are the basic tastes?

In taste buds on the tongue, in the throat and on the roof of the mouth. The slide lists four tastes: sweet, sour, salty, bitter.

Why does food taste bland when your nose is blocked?

Taste and smell work together a lot.

What shapes our taste: genes or experience?

Both. How sensitive we are to bitter taste is partly genetic. What we think is pleasant (sour or bitter) is strongly shaped by culture.