Sensory and Perception Team 4: Amanda Tapp, Celeste Jackson, Gabe Oswalt, Galen Hendricks, Harry Polstein, Natalie Honan and Sylvie Novins-Montague
Our Senses sensation: simple stimulation of a sense organ perception: the organization, identification, and interpretation of a sensation in order to form a mental representation transduction: what takes place when many sensors in the body convert physical signals from the environment into encoded neural signals sent to the central nervous system
Psychophysics and Measuring Thresholds psychophysics: methods that measure the strength of a stimulus and the observer s sensitivity to that stimulus absolute threshold: the minimal intensity needed to just barely detect a stimulus threshold: boundary Weber s law: the just noticeable difference of a stimulus is a constant proportion despite variations in intensity just noticeable difference (JND): the minimal change in a stimulus that can just barely be detected
Signal Detection and Sensory Adaptation signal detection theory: an approach to psychophysics, the response to a stimulus depends both on a person s sensitivity to the stimulus in the presence of noise and on a person s decision criterion examples: memories, moods + sights, noise sensory adaptation: sensitivity to prolonged stimulation tends to decline over time as an organism adapts to current conditions (very useful!)
Illusions
Light Visible Light - The portion of the electromagnetic spectrum that we can see Light waves Length - Distance between peaks, determines hue Amplitude - Height of peak, determines brightness Purity - # of wavelengths, determines saturation
The Human Eye
Phototransduction in the Retina Photoreceptor cells - contain light sensitive pigments which transduce light into neural impulses Cones - Detect color in daylight, focus on detail (6 million) Rods - Active in low light, sense shades of grey (120 million)
Phototransduction in the Retina Photoreceptor cells send signals to Bipolar cells which then transmit signals to Retinal Ganglion Cells (RGCs) The axons of the RGCs form the optic nerve which exits through a hole in the retina (leaving a blind spot)
Color
Color Mixing Reflection Absorption
The Visual Brain Area V1 Primary visual cortex Edge orientation Ventral stream Shape and identity Dorsal stream location and motion
Attention Binding Problem: phenomenon that links features together to allow us to see distinct objects instead of random disjointed shapes Illusory Conjunction: a perceptual mistake where features or shapes are incorrectly combined
Feature Integration Theory States that attention IS NOT required to notice factors about a stimulus but attention IS required to piece them together properly and without errors Attention is the glue that connects features together to prevent illusory conjunction Parietal lobe is necessary to this process
Perceptual Consistency Even when a major change occurs in something you are familiar with, you can still recognize it Recognition centers in the temporal lobe may be optimized for recognizing faces (modular view v. distributed representation)
Gestalt Perceptual Grouping Rules
Monocular Depth Cues Ames Room
Binocular Depth Cues Uses disparity between images received by the eyes
Motion and Change Humans are very sensitive to motion Brain subtracts your motion from the eye s images Waterfall effect: when you look at something moving down for a while, then look away, everything appears to be moving up Sensors analogous to color sensors cause waterfall effect
Apparent Motion Rapid, successive stationary images appear to be moving Used in signs, movies, and TV
Change and Inattentional Blindness Change Blindness is where people fail to notice changes in the visual details of a scene Inattentional Blindness is where people fail to notice things that do are not in their focal area
Audition
Audition
The Body Senses Haptic perception results from our active exploration of the environment by touching and grasping objects with our hands
Touch The left half of the body is represented by the right side of the brain More of the brain is devoted to parts of the skin surface that have greater spatial resolution Distinction between what and where system
Pain Pain is important! Pain receptors are not only on the skin, but also inside of our bodies. It indicates damage or potential damage to the body
Pain Referred pain is when sensory information from internal and external areas converge on the same nerve cell in the spinal cord Gate control theory: signals arriving from pain receptors in the body can be stopped by interneurons in the spinal cord via feedback from two directions
Body Position, Movement and Balance Vestibular system is responsible for balance -three fluid filled semi-circular canals and adjacent organs located next to the cochlea in each inner ear
The chemical senses: Smell Smell - Flavour: a perceptual experience - Olfactory Epithelium is a mucous membrane where odors travel from to the Olfactory Bulb - Contains Olfactory Receptor Neuroms (ORNs) that initiate the sense of smell
Smell - Oflaction (smell) is associated with memory - Pheromones: odorants emitted by other members of certain species - Affects the behaviour/physiology of the animal - E.g: parents can smell own children from others and vise versa (infants can detect mothers breast) - Some discourse about human pheromones
Taste - Papillae, taste buds, taste receptor cells, microvilli - Microvilli have tasting molecules that respond to food - Many people lose most by age 20 - Five primary taste sensations: salt, sour, bitter, sweet, umami - Umami is least common