Sensation & Cognition

• Cognition is the mental process of gaining knowledge and understanding through thought, experience, and senses like vision, smell, taste, hearing, and touch.
• Cognitive processes include attention, sensation, perception, and memory.

Sensation

• Sensation is a physiological process involving senses and sense organs gathering external stimuli and input about the environment.
• This information is then sent to the brain for processing initially.
• Senses only respond to a limited range of environmental stimuli
• Absolute threshold is the lowest level at which a sensation can be experienced.
• Sensation involves reception, transduction, and transmission.
• Reception is the activation of sensory receptors by a stimulus
• Key sensory receptors include chemoreceptors (chemicals), thermoreceptors (temperature), mechanoreceptors (pressure), and photoreceptors (light).
• Transduction involves converting a sensory signal into an electrochemical signal in the nervous system, and occurs in the sensory receptor
• Transmission involves sending sensory information as neural impulses to the relevant brain area.

Perception

• Perception actively organizes and interprets the raw sensory information, creating meaning from sensation.
• Perception processes include selection, organization and interpretation.
• Selection involves feature detectors that filter stimuli by responding to specific features, and ignoring the rest.
• Salience is determining how much something attracts our attention, with factors including visual/aural stimulation, needs, interests, and expectations.
• Organization arranges sensory stimuli features in a meaningful way.
• Gestalt principles describe how humans group similar elements, recognize patterns, and simplify complex images for visual perception
• Similarity involves elements with a stimulus pattern being similar in size, shape or colour.
• Proximity involves things that are close together seem more related than things that are spaced farther apart.
• Figure ground involves certain objects that are automatically identified as figures, while others become meaningless background
• Interpretation is giving meaning to sensory stimuli
• Perceptual sets - a mental predisposition or readiness to perceive stimuli in a particular way based on previous experiences, expectations, beliefs, and context, can influence interpretation
• Schemas are mental frameworks about a concept or entity. These can help guide our perceptual sets

The Role of Attention in Memory

• The cocktail party effect is the ability to focus on a particular stimulus while filtering out a range of other stimuli
• Ways to separate the voice of the person speaking to, from the voices of surrounding conversations include: direction of voice, body language, speaking voice differences, accents, and transition probabilities.
• Selective attention involves focusing on particular stimuli and filtering out irrelevant information
• Divided attention, also known as multitasking, is when mental focus is on multiple tasks or ideas at once.

What is Memory?

• Memory is an active information processing system that receives, stores, organises and recovers information.
• Memory involves encoding, storage, and retrieval.
• Encoding translates information into a neural code for brain processing.
• Storage involves retaining information over time.
• Retrieval accesses stored information.

Brain Structures

• Hippocampus located deep within the temporal lobe, and its role is in memory and learning.
• Cerebellum regulates posture, balance, judging distances, and fine motor skills particularly in the hind brain
• Amygdala is a collection of nuclei deep within the temporal lobe that regulates emotions and modulates the fear response, forming part of the limbic system.
• The hippocampus is involved in declarative memories and spatial relationships, and interacts with the amygdala to form episodic memory of emotional events.
• The hippocampus temporarily holds long-term memories before transfer to the cerebral cortex, consolidating STM into LTM
• Injury to the hippocampus impairs the ability to process new declarative memories.
• The cerebellum plays a large role in implicit memories, including procedural memory, motor learning, and classical conditioning.
• It stores procedural memories of learned sensorimotor skills and simple reflexes acquired through classical conditioning, then these are stored long term in cerebral cortex.
• The amygdala regulates emotions ad attaches them to memories.
• It facilities encoding memories at a deeper, emotionally salient level and transfers STM to LTM
• It is involved in procedural memory storage, influenced by emotions/stress
• Damage is likely to form conscious explicit memories, but likely will not form an implicit memory about the emotional qualities, so the person can't produce a fear response.

Henry Molaison (Patient H.M)

• Patient H.M. had portions of his hippocampus removed to alleviate severe epilepsy.
• He experienced fewer seizures, but experienced anterograde amnesia (inability to form new declarative memories) and could not permanently store new information.
• H.M. experienced retrograde amnesia and could recall childhood events but not experiences a few years before the surgery
• He could also improve performance on various motor tasks, despite being unable to remember learning them.
• Studies on H.M. suggest the hippocampus is essential for declarative memory, but not procedural memory.