Weber-Fechner law

S=C*lgI

S - subjective sensation C - coefficient of proportionality

I - stimulus intensity

Effects of Weber-Fechner law

The relationships between stimulus and perception are logarithmic.

Logarithmic relationship means that if a stimulus varies as geometric progression, the corresponding perception is altered in arithmetic progression.

More expressed sensitivity lies in the range of small values of the stimulus

The main properties of senses

6. Aftersensation (a sensory impression that persists after the stimulus has ceased)

7. Latent period (the delay between the receipt of a stimulus by a sensory nerve and the response to it )

Visual system

is the part of the central nervous system which gives organisms the ability to process visual details.

It detects and interprets information from visible light to build a representation of the surrounding environment.

Visible light

has a wavelength in the range of about 380 nm (violet color) to about 740 nm (red )

*

§

a

o

£

c

pigment

epithelium

rods

cones

outer limiting membrane^

horizontal cells — bipolar cells —

ganglion cells -

Inner limiting f membrane '

ресничная мышца

Ciliary ^

Muscle

Visual system

радужная оболочка

роговица

Cornea

Pupil зрачок

/

Желтое пятно

Optic

Nerve

Rods=b+w vision Cones = c. vision, f.details

Highest visual acuity

Myopia

Visual system

1. Binocularity provides

• spare eye

• wide field of view (horizontal -190°)

• binocular summation (ability to detect faint objects)

• stereopsis is the ability to see three- dimensionally provided by the two eye's different positions

2. Accommodation is the process by which the eye changes optical power to maintain a focus on an object as its distance varies.

3. Aftersensation of the eye: 0,1...0,25 sec

4. Adaptation

• Dark Adaptation takes about 30 min,

• Light Adaptation takes 15-60 sec

2. Winking of 5-10 times/min causes 10-20% losses of information about environment

• 

  Prevention of Vision Problems

  Have periodic eye exams

• Follow a healthy lifestyle.

• Eat a nutritious diet for eye vision.

• Wear eye protection when involved in activities that could cause traumatic risk to your vision (sports, dealing with firearms....) Avoid hazards (fireworks..).

To prevent eyestrain

rest your eyes for five min / hour

blink regularly

change the focus periodically

he ear and the hearing mechanism

Auditory perception is the ability to perceive sound by changes in the pressure of the surrounding medium

Sound is the mechanical vibrations in gaseous, liquid or solid media

стремечко

(attached to oval window)

ьня

олоточек наков \ Incus

\ Malleus \

Nerves

Cochlea

Улитка

External Auditory Canal

Eardrum

Барабанная перепонка

outer ear ^middle inner ear

ear

The physical characteristics of the sound wave

Wavelength, A, m Frequency, f, Hz Amplitude, A, m

f=i/T

A=cT

A=c/f