sensation and perception flashcards

 Our senses allow simulies to convert into electrical signals that are sent to the brain in order to process information. 

Absolute threshold- a minimum stimulation is able to pick up weak sensory signals (ability to see the light of candle in a dark room) 

Signal detection theory- model predicting how and when a person will pick up a weak stimulus according to their surrounding (when walking in the night u might be more aware of your surroundings) 

Weber's Law- we perceive differences on a logarithmic rather than linear scale  (% of change that matters)                                                                                                                                                                                                                                                                                          Difference threshold- a person is aware of the difference (non-linear) 

Sensations into perceptions ==> 

Transduction: Eyes take in energy from the light and transform into neurotransmitters through…

Waves length and frequency which determines HUE (color or shade we see)   

Waves amplitude(how high the wave goes) determines brightness/value…(light complexity) determines their purity 

Amplitude: amount of energy in a given light wave (how high/low the wave goes.) 

• Greater amplitude- higher intensity and brighter color 

Effect- chromostereopsis: pure colors at the same distance from the eye appear at different disfaces. (Warm Colors come forward while darker color retreat.) 

Biological process in Sensations:

Two opposing wavelengths tire pit the retina

Colors hue depends on length and frequency of the lightwave and its amplitude affects its brightness, amplitude is the given amount of energy in a wavelength 

The higher number of Pure spectral color there is less saturation 

The retina contains over 200 million photoreceptor cells called

(Rods and cones) 

• Rods-sensitivity in (dim lighting) populate the periphery, the region surrounding the fovea, rarely in the fovea

• Cones- fine details (bright light) they are placed around the fovea 

When rods and cones simulated chemical changes activate cells behind them. Other cells are activated which then form the optic nerve, which carries information from the eye into the brain. 

Optic nerve then goes to the thalamus and then its visual cortex, which sits in the back of the brain in the occipital lobe.

Information from eye lobes go to opposite sides of cortex. Nervous systems analyzes differences in there light.

Edges- add change in brightness to get sharp edges (better visual) 

Feature detectors- respond to different stimulus 

Parallel processing- ability to process and analyze many aspects of the situation at once (links individual features into a whole scene)

 An edge is created by color differences alone, changes in brightness give sharper edges, 

To capture light retinas use photosensitivity to detect a change in light intensity and uses that to send the brain a message which the brain outputs as an image, brightness and edges give sharp images which remove the blurry 

Perceptual tools: 

• Shadows- The brain uses shadows to analyze the scene 

• Retinal disparity-  allows your left and right eye to view slightly different images to aid perception 

• Depth perception- allows for you to estimate the distance between objects and yourself 

• Monocular cues- depth perception but don't require both eyes but base off of occlusion relative size, relative height, texture gradient, familiar size, linear perspective, aerial perspective, and relative brightness 

*Occlusion- an object that blocks the view of another object must be in front of it 

*Relative size-  objects that are further away look smaller relative to their normal size 

*Texture gradient- as a texture gets further away there is less of a texture gradient because its less noticeable

* Relative height- objects that are taller appear further than objects that appear lower 

*Familiar size- Knowledge of the normal size of something can give so you a visual cue of its depth 

*Linear perspective- the idea that parallel lines seem to converge as they go further away into the distance 

*Aerial perspective- objects that are further away appear to be even hazier and bluer 

*Relative brightness- brighter images seem to be closer, and shaded images are further away 

Light shadow and color can also provide misinformation to in cases such as the shepherd's table 

Combining shading, color and depth cues give an accurate perception of a scene.

Perception tools are guided through principals like;

• Similarities- We tend to form groups through similarities. 

• Form- we see things as their simplest form 

• Proximity- the closer things are together, we tend to group them together 

• Good Continuation- a preference of organizing form in a way where the style does not differ and remains smooth 

• closure - filling in information to complete perspectives 

• Pareidolia - is the tendency to use incomplete information to draw out a unique perspective 

• Shape consistency- the ability to perceive the shape of a rigid object as constant bugpite the angle you’re viewing it from 

Gregory Top down processing;

Ambiguous figure-sudden perceptual reverses occur when the stimulus stayed deunchanged

An object can have 2 perspectives due to the brains inability to choose between two equally hypothesis on an objects orientation 

Gibson Bottom up processing … sensation is perception;

Bottom up processing- the perception in which was forged by evolution and no learning is needed  

This is possible with affordances- meaning that an environment gives