Psych 100 Midterm

The cortex is referred to as grey matter, because its cells are not wrapped in a fatty white sheet (myelin).

The inner parts of the brain that are wrapped in a fatty white sheath are often called white matter.

Sensation is picking up the stimuli in the environment and is the process of gathering information from the environment. Perception is organizing and selection the senses, it is how you interpret the sensations.

The just noticeable difference is the smallest difference between two similar stimuli that can be distinguished.

Weber's Law: The minimum change in intensity/length/weight goes up as its intensity goes up.
Fechner's Law: each JND represents an equal step in the psychological magnitude of a sensation.
Stevens' Power Law: different numbers were assigned to sensations of different magnitudes - can study sensation over a great range.

Signal Detection Theory: every stimulus requires discrimination between Signal(stimulus) and noise(background stimuli and random activity of nervous system).

Pitch - Frequency, Loudness- Amplitude, Timbre - Complexity

Dorsal - Where pathway - enables us to perceive location of objects so we can do correct actions to those objects (ie. catch a ball)
leads to the upper occipital and parietal lobes.
Ventral - What pathway * identify objects and give meaning to them goes to the temporal lobe

Damage to ventral pathway leads to visual agnosia.Types of visual agnosia:Form Agnosia - can't identify shapesVisual Object Agnosia - know shape, not objectProsopagnosia - can't identify human faces

It's an area of brain activated specifically by faces.

In the retina, when one receptor gets excited, its neighbour gets excited as well. With lateral inhibition, edges or boundaries become intensified.

When the activity of cell changes by being onset or offset by light - we call this the receptive field.
Excitation is when light shines on the middle of the cell. Inhibition is when light stops shining on its outside.

When an image lands on your retina, it is an inverted mirror image (upside-down, and left-right reversed). The image projected is 2D, but you must make it 3D. There's also a blind spot, where the axons form the optic nerve, so we don't actually see anything. But your brain fills in the details at the perceptual level.

Depth perception is intimately connected with perceptual constancy. This means that we can maintain a perceptual judgment as the external stimulus changes.

Ex:
Size constancy: even though visual image of object changes with distance - our perception of that object's size does not.
Visual Constancy: visual features of stimuli remain perceptually constant.
Lightness constancy: brightness constancyShape constancy:size

Helmholtz suggests that all of these theories are due to unconscious inferences performed by the visual system. IT assumes that the information contained in the stimulus is insufficient to generate the full perceptual response.

Structuralist - perception is the joining together of elementary sensations
Gestalt - whole was not necessarily equal to sum of its parts - there can be a level of pattern and order at the whole that is not simply accounted for by examining each of its parts in isolation.