below conscious awareness. We have automatic procedures.
We have individual differences. Some people can smell, taste,
hear, etc. better than others. Absolute threshold: consistency.
The minimum energy to be detected 50% of the time.
-Just noticeable different (DND): The next threshold – just
noticeable difference from the absolute threshold. How much
energy you need to recognize that the intensity has increased. If
it’s really loud in a room already, you won’t be able to notice the
noise. Weber fraction. It could be going up or down. Fraction
applies to everyone in the same way. It’s incredibly similar to
everyone. Cultural or geographical differences have no effect at
The Visual system
-The most important. More of our brain is dedicated to vision
than to other senses put together. Why is vision so important?
Why is it important than any other sense?
-We evolved our system to be very specific. We only see a bit of
energy that flows all the time. Our naked eyes are not avaiable
to see ultraviolet. We have the visible white spectrum. The peak
of the light- amplitude. We measure the wavelength as well.
Wavelength gives us the color that we see. We see the little
light of the energy. We have adapted to this spectrum that is
most facilitated for our brain. Other species see things in
different wavelength. We could have evolved to see other
Details of the human eye
-Your eye doesn’t see. The brain sees – the primary vision
cortex. Light comes in, moves past the pupil and being refracted
by the lens. The pupil stays the same. it’s the iris that contracts.
The pupil helps to make sure the light goes where it’s supposed
to go. Make sure the light goes to the fovea (optic disk).
Specialized in seeing fine detail. If light goes to a bent degree,
we will see things blurry. The light might not hit the fovea. Then