PSY3108: Perception — Quick Reference

Perception is the brain's interpretation of sensory input, while sensation is the registration of physical stimuli by sensory receptors. The broader term "perception" often encompasses the entire process from stimulus to action.
Your experienced world is constructed from nervous system activity combined with prior knowledge. Perception is fundamentally dependent on the properties of sensory receptors and their interaction with stimuli.
Distal stimuli are the actual objects or events in the environment. Proximal stimuli are the representations of these distal stimuli on your sensory organs (e.g., the image projected onto the retina).
The Principle of Representation states that perception is based on these internal representations received by receptors, not on direct physical contact with the external world.

Perception is a dynamic process involving seven main steps, heavily influenced by knowledge at multiple stages:

Distal Stimuli from the environment reach the sensory receptors.
Proximal Stimuli are formed as representations of the distal stimuli on the receptors (e.g., light reflecting off a tree forms an image on the retina).
Transduction occurs: environmental energy (like light) is transformed into electrical signals by sensory receptors.
Neural Processing: these electrical signals are transmitted through neural pathways to the primary cortical areas associated with each sense.
Perception: this is the conscious awareness of the stimulus.
Recognition: the process of identifying what the stimulus is (which is distinct from simply being aware of it).
Action: motor responses are initiated based on the perception and recognition of the stimulus (e.g., reaching for an identified object). This process is continuous and interactive.

Reinforcing earlier concepts, perception fundamentally relies on the representations formed on receptor surfaces (proximal stimuli), as opposed to direct interaction with the actual original objects or events (distal stimuli).
For example, when you see a tree, your brain processes the image of the tree on your retina (proximal stimulus), not the physical tree itself (distal stimulus).

Bottom-up processing is data-driven, starting from the sensory input and building up to perception. It relies primarily on the raw information received from the senses.
Top-down processing is knowledge-driven, where expectations, prior experiences, memory, and context influence how a stimulus is perceived. For instance, your expectation might help you rapidly identify a vaguely patterned object as a moth.
In reality, perception often arises from a continuous interaction between both bottom-up (sensory input) and top-down (knowledge and context) processes, integrating direct stimulation with an individual's accumulated