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Module 3.1Sensing Our World: Basic Concepts of SensationSensation� Sensation� a process by which our sensory receptors and nervous system receive and represent stimulus energy� Perception� a process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and eventsSensation� Sensory receptors� Eyes� Ears� Nose� Mouth� Joints, muscles� SkinSensation� Gustav Theodor Fechner: Elements of Psychophysics (1860)�����������������������Absolute and Difference Thresholds� Absolute Threshold�� minimum stimulation needed to detect a particular stimulus� usually defined as the stimulus needed for detection 50% of the time� Difference Threshold� minimum difference between two stimuli that a subject can detect 50% of the time� just noticeable difference (JND)� increases with magnitudePsychophysical Theory� Signal Detection Theory� predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise)� assumes that there is no single absolute threshold� detection depends partly on person�s� experience� expectations� motivation� level of fatigueAbsolute and Difference Thresholds� Weber�s Law-� to perceive a difference between two stimuli, they must differ by a constant proportion� light intensity-� 8%� weight-� 2%� tone frequency-� 0.3%� Sensory adaptation-� diminished sensitivity with constant stimulationModule 3.2Vision: Seeing the LightSeeing the Light� Vision� Light energy converted to signals the brain interprets to produce experience of sight� Light� Physical energy, electromagnetic radiation� Wavelength corresponds to colorSeeing the Light The optics of visionThe Eye� Parts of the eye� Cornea� Iris� Pupil� Lens: accommodation� Retina: rods and cones� Bipolar cells, ganglion cells� Optic nerve (blind spot)� FoveaParts of the Eye (Figure 3.3)Visual pathwaysLight to Neural Impulses (Figure 3.5)Feature Detectors� Neurons that respond to specific features of the visual stimulus� Within the visual cortex� Discovered by Hubel and WieselColor VisionNegative AfterimagesColor-Deficient VisionModule 3.3Hearing: The Music of SoundSound Waves� Based on vibrations� Amplitude� Height of wave� Decibels� Frequency� Number of waves per second� PitchSound Waves (Figure 3.10)The Ear� Passage of sound waves� Outer ear� Eardrum� Ossicles� Oval window� Cochlea: basilar membrane, hair cells� Auditory nerveSound Waves to Neural Impulses (Figure 3.11)The cochleaThe Organ of CortiPerception of Pitch� Place theory� �Location on basilar membrane determines pitch� Frequency theory� Basilar membrane vibrates at same frequency as sound wave� Volley principle� Groups of neurons fire in rotationHearing Loss� Conduction deafness� Damage to middle ear� Nerve deafness� Damage to hair cells or auditory nerveSounds and Decibels (Figure 3.12)Module 3.4Our Other Senses: Chemical, Skin, and Body SensesOlfaction� Smell� Chemical molecules� Specific smells depend on shape� Nose, olfactory nerve, olfactory bulb� Important for food flavor� PheromonesSkin SensesPain� Receptors in� Skin, muscles, joints, ligaments, teeth� Gate-control theory of pain� Mechanism in spinal cord controls pain messages� Bottleneck may block pain� Role of endorphins� AcupunctureKinesthesis� Receptors in joints, ligaments, muscles� Information about� Movement of body parts� Relative positive of body parts� Allows for automatic movementsVestibular SenseModule 3.5Perceiving Our World: Principles of PerceptionPerceptionProcess by which the brain interprets sensations, turning them into meaningful representations of the worldAttention� First step in perception� Selective attention� Influenced by� Motivational states� Repeated exposure� Increased attention� HabituationPerceptual SetLetter B or Number 13? �(Figure 3.18)Visual Processing� Bottom-up processing� Focus on specific shapes, individual features� Top-down processing� Experience and knowledge shape perceptionGestalt Principles� Gestalt: �unitary form,� �pattern,� �whole�� Laws of perceptual organization� Figure and ground� Grouping� Proximity� Similarity� Continuity� Closure� ConnectednessGestalt Laws of Grouping (Figure 3.24)Perceptual Constancies� Tendency to perceive an object as remaining the same even when retinal image changes� Examples� Shape constancy� Size constancy� Color constancy� Brightness constancyShape Constancy (Figure 3.25)Depth Perception� Depth Perception� ability to see objects in three dimensions� allows us to judge distanceDepth Perception� Binocular cues� retinal disparity� images from the two eyes differ� closer the object, the larger the disparity� convergence� neuromuscular cue� two eyes move inward for near objectsDepth Perception� Monocular Cues� relative size� smaller image is more distant� interposition� closer object blocks distant object� relative clarity� hazy object seen as more distant� texture� coarse --> close������������������������ fine --> distantIllusionsVisual Illusions� Examples� Muller-Lyer illusion� (Carpentered-world hypothesis)� Ponzo illusion� Impossible figures� Moon illusion� Apparent movement� Stroboscopic movement� Phi phenomenonVisual Illusions (Figure 3.28)Subliminal Perception� Stimuli presented below level of conscious awareness� Can it influence attitudes or behavior?Extrasensory Perception� Parapsychology: scientific study of psi and related� phenomena� Extrasensory perception (ESP) or psi� Telepathy� Clairvoyance� Precognition� PsychokinesisExtrasensory PerceptionGanzfeld: Homogenous visual field.Subjects in a ganzfeld experimentsit in a comfortable chair, have theireyes covered by ping-pong ballsand hear white noise (i.e., static).The atmosphere is a relaxed oneand the subject reports anyimpressions that he/she is awareof.Extrasensory Perception���� Psi, as demonstrated� under laboratory conditions, appears to be a very weak and unstable phenomenon.� Parapsychologists have had a lot difficulty creating the exact experimental conditions under which acceptable and reliable psi effects can be demonstrated.Module 3.6Application: Psychology and Pain ManagementPain Management� Distraction� Bottleneck at the �gate�� Such as rubbing, cold packs� Changing thoughts and attitudes� Negative pessimistic self-evaluations: more pain� Rational alternatives: cope more effectively� Accurate information� Meditation� Biofeedback: electromyographic, thermalWhat is noise in signal detection theory?biguous stimuli which can be generated either by a known process. (called the signal) or be obtained by chance (called the noise in the. SDT framework). For example a radar operator must decide if what. she sees on the radar screen indicates the presence of a plane (the signal) or the presence of parasites (the noise).
Which of the following describes the difference between sensation and perception?Sensation occurs when sensory receptors detect sensory stimuli. Perception involves the organization, interpretation, and conscious experience of those sensations.
What is the detection of stimuli?detection of stimulus involved in sensory perception Gene Ontology Term (GO:0050906) Definition: The series of events involved in sensory perception in which a sensory stimulus is received and converted into a molecular signal.
What is signal detection theory example in psychology?In the presence of loud music, you would still be able to hear phone ringing or vibrating. On the contrary, you would not be able to detect your phone ringing or vibrating in the presence of noise other than ringtone or vibration. This is the most common example of SDT we can find in our daily lives.
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Which of the following theories predicts when and how we detect a stimulus amid background noise?
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