Sensation and Perception

Sensation & Perception

• Sensation involves the detection of stimulus energies by the sense organs.
• Perception is the brain's interpretation of sensory information.
• If relying solely on sensation, one would see in 2D.

Transduction

• Transduction transforms physical senses into neural signals.
• Light is transformed into vision via light striking the retina.
• A cascade of chemical and electrical events begins and is ultimately turned into neural impulses.

Vision

• You can find your blind spot by closing one eye and staring at a fixed point while a second point disappears.
• Seeing is complex, involving parallel processing, bottom-up processing, and top-down processing.
• Feature Theory and Parallel Processing are needed for vision to work properly.
• Features are simple, distinct, and represented in the brain.
• Parallel processing must occur for proper vision to work.
• A feature detection approach to pattern recognition is a problem-solving process.
• Neurons have preferred angles or orientations, responding to a specific "feature".

Serial vs Parallel Processing

• Parallel processing involves multiple processes at the same time.
• Serial processing involves steps in a series, one after the other.

Bottom-up vs. Top-down Processing

• Bottom-up processing involves taking sensory information and then assembling and integrating it.
• Top-down processing involves using models, ideas, and expectations to interpret sensory information.
• Perception uses a combination of both top-down and bottom-up processing.

Schizophrenia

• Schizophrenia is a psychotic disorder that impairs an individual’s ability to test reality.
• It affects cognition, emotion, and behavior with no single defining feature.
• Prevalence is less than 1%.
• Schizophrenia is not the same as split personality disorder or DID.

Symptoms of Schizophrenia

• Positive symptoms are additions that include delusions and hallucinations.
• Negative symptoms are deficits that include anhedonia/amotivation, flat affect, and alogia.
• Other symptoms include psychomotor and cognitive symptoms.

Schizophrenia Treatments and Causes

• The dopamine hypothesis is one potential cause of schizophrenia, and indicates that typical antipsychotics and atypical antipsychotics can treat the disorder.
• Ketamine and PCP are psychomimetic glutamate antagonists that produce similar symptoms.
• Hypofunction of NMDA receptors may be involved in the disorder.
• The Diathesis-Stress Model of schizophrenia includes genetic vulnerability (diathesis) and a precipitating situation (stress).

Taste and Smell

• Taste (gustation) and smell (olfaction) are chemical senses that work together closely.
• Anosmia is smell "blindness".
• Taste and smell use bottom-up processing, receiving sensory information using receptor cells.
• Beer and Wine tasters follow a series of steps: look, agitate, smell, taste for a full sensory experience.

Multisensory Perception

• The McGurk Effect demonstrates how we use visual information to understand speech.
• The Rubber Hand Illusion demonstrates the combination of touch and vision.