Introduction to psychology: Highlights on sensation and perception

Perception is a type of mental activities in which an animal gains access to some features of the current state of its environment. The reality of the objects and events in one's surroundings are revealed through sensory signals, which arise from impact of materials and energy from environmental objects on the perceiver’s sensory organs. Perception results from an exchange of physical forces between a nervous system and the outside world, such as light, sound, heat and mechanical impact. There are two types of input, contact and ambient input. Sensation and perception involve transducing information from outside to the internal media of the mind. A person experiences objects and events in the world through a body, i.e. through a nervous system that encodes, transmits and integrates signals from the outside world. 

In the Chapter about Sensation and Perception, we need to master the following key concepts.

We have five senses, what are they?

Vision is the most important sensory channel for humans. For vision, we need to master the following key concepts.

How do people perceive shape, contours, features and color? 

The answer is with light-sensitive neurons – rods and cones. Which one is more sensitive to color? Which one is more sensitive under dim light? Which one is more concentrated in the fovea area in the retina?

Where is the retina located and what does it do? In the back of the eyeball, it holds all the light-sensitive neurons, i.e., rods and cones. 

How does light information pass from the eyes to the brain? 

Inside the retina: from rods and cones to the bi-polar cells, then to the ganglion cells (which make up the optic nerve). 

Outside of the retina: the optic nerve go to the thalamus, then to the visual region in the occipital lobe, where feature detectors are located. 

How do we perceive depth, or distance, or how far away an object is from you? This is how we create a three-dimensional vision. 

The answer is we use two broad types of cues, binocular and monocular. 

Binocular cues include disparity and convergence. 

Monocular cues include overlap, motion parallax, linear perspective

Perceptual constancy is also important for vision, including shape, size and color constancy.  

The following article talks about the perception of the color of black. 

https://news.mit.edu/2019/blackest-black-material-cnt-0913