Human Visual System Quiz

Sensation and Perception

• Stimulus: Any physical energy that triggers a response in a sense organ.
• Sensation: The reception of physical energy by a sense organ.
• Perception: The brain's interpretation, analysis, and integration of stimuli. This is a multi-stage process involving the sense organs and the brain.
• Stimulus energy is transformed into neural impulses and processed by different brain areas.

Brain and Perception

• Different brain areas are responsible for processing different senses
• Visual processing, for example, is specialized, with different areas within the visual cortex handling specific aspects.

Critical Role of Sensation and Perception

• The world offers a vast amount of sensory input.
• Our sensory and perceptual system is tasked with selecting and focusing on relevant information.
• This prioritization allows for efficient processing within individual senses such as vision.

Visual Perception

• Human vision only processes a specific range of wavelengths.
• Retina: A layer of photoreceptor cells in the eye.
• Fovea: A small pit in the retina providing the sharpest vision.
• Cones: Photoreceptor cells sensitive to color, functioning well in bright light.
• Rods: Photoreceptor cells sensitive to dim light, mainly used for black-and-white vision.

Colour Perception

• A single cone type's activity alone is insufficient for color identification.
• The pattern of activity across the three cone types is crucial for colour perception.
• The brain processes this pattern to interpret colors.

Is Sensation and Perception Enough?

• Colour constancy: The ability to perceive object colours as consistent, even when the reflected light changes.

Gestalt Psychology

• Emphasizes how we organize pieces of information into meaningful wholes.
• Perception is not simply the sum of individual parts but involves a more organized interpretation.

Sensation-Perception-Cognition

• Sensation provides raw data to the brain.
• Perception processes this data.
• Cognitive processes elaborate on this perceptual interpretation.

Perceiving Depth

• Depth perception allows us to experience the world in three dimensions.
• Retinal images are inherently two-dimensional.
• Depth perception involves a complex interplay between sensation and internal cognitive processing.

Cues for Depth Perception

• Relative size
• Light and shadow
• Interposition (overlap)
• Texture

Size Constancy

• Our perception of an object's size remains consistent, even with changes in distance.
• It is another way we gain a cognitive awareness of our surroundings and can act as a cue for depth perception.

Face Perception

• Humans have a strong preference for faces, evident from a young age.
• Valenza et al (1996): Infants showed a preference for face-like patterns compared to scrambled patterns.
• Mondloch et al (1999): Young infants show a preference for normal versus abnormal/inverted faces. By 12 weeks, this preference becomes more pronounced.
• Faces are vital for communication. Indicators such as facial expressions, eye contact, and eye direction impart meaning. Field et al (1982): Demonstrated newborns can discriminate and imitate facial expressions observed in live displays.

Face Recognition

• Inversion effect: Upside-down faces are more difficult to recognize than upright faces; configural information is affected. Yin (1996) and the Thatcher effect (Thompson, 1980) support this.
• Holistic processing: The brain processes faces differently from other objects, relying on configuration rather than individual features. Bruce and Young (1986) proposed a model explaining the face recognition process.
• Prosopagnosia: A condition affecting the ability to recognize faces, referred to as "face blindness."

Embodied Cognition

• Cognition is grounded in our sensory and motor systems. No separate mental representations are needed.
• Representations are distributed across sensory and motor areas of the brain, allowing connections between perceived actions and sensory input.
• "Mental simulation" is a key component of embodied cognition.

Interaction between Body and Mind

• Body-mind effects: Witt & Brockmole (2012) showed that holding specific objects during a task can influence how easy or difficult it is to perceive another stimulus.
• Mind-body effects: Tucker and Ellis (2004) showed that the size of an object perceived influenced the appropriate response switch, demonstrating how perception influences our actions.

Action Observation

• Observing actions activates related sensory and motor representations, making specific objects more easily recognized; Helbig et al (2010).

Traditional vs. Embodied Cognition

• Traditional cognition proposes separate mental representations for sensory, motor, and cognitive functions.
• Embodied cognition stresses that these functions are interconnected within the brain.

This quiz explores key concepts related to the human visual system, including the functions of the retina, color vision, and the roles of the brain in sensation and perception. Test your knowledge on how we perceive colors and interact with the outside world through our sensory system.