Textbook Notes (363,314)
Canada (158,331)
Psychology (1,091)
PSYC 100 (329)
Prof. (24)


11 Pages
Unlock Document

Queen's University
PSYC 100

Sensation Sensation-physiological process that underlies transformation of the chemical, mechanical, light, and sound energy in the world into electrical activity in the brain -gathering information about the environment Perception- psychological process involved in selection, organization, and interpretation of sensations Transduction-conversion of physical energy into electrical potentials- occurs in sensory receptor cells, which are specialised neurons -senses act as a gate to the world and is essential for survival -our senses give us just enough information so that we can behave appropriately -senses respond to a restricted range of energies in the world -people are more sensitive to change than to constant stimulation, adaption -our brain has no direct access to physical objects -Sensing requires action- it’s not a passive process -we cannot sense magnetic fields, but some animals can because of evolution -each receptor varies its responses to stimuli that differ quantitatively and qualitatively Quantitative- amounts or quantities that can be measured objectively Qualitative- pertaining to some quality or characteristic other than magnitude -all stimulus characteristics must be coded, and using them, sensory system passes the information along specific anatomical pathways to the brain’s cortex, where further processing occurs so that sensations are organized and interpreted as perceptions Doctrine of Specific Nerve Energies-Johannes Muller -all sensory receptors are uniquely sensitive to particular types of energy Receptor Cells- specialized neurons that transduce (convert) physical energy (light, chemical, mechanical, or sound) into electrical signals Adequate Stimulus- type of physical energy to which a sensory receptor is especially tuned Just-Noticeable Difference-minimum level of detectable difference in the magnitude of a stimulus -smaller it is, the more sensitive you are Fatigue- neurons subjected to steady and continuous stimulation become unable to send signals, probably because of a temporary depletion in the neurotransmitters that send signals across synapses Sensory Adaption-change, usually a decrease, in sensitivity that occurs when a sensory system is repeatedly stimulated in exactly the same way, causes fatigue -allows organisms to concentrate on changes for survival and ignore things that are repeated -reduces the amount of data the brain needs to process information but not reducing the amount of information Habituation- decrease in perception or behaviour in response to a stimulus when an organism has learned that that stimulus is irrelevant -sensory adaption and habituation causes the loss of sensitivity in smell and taste Population/Pattern Code- information is conveyed across a whole population of cells rather than single or a group of nerve cells Place/Labeled-Line Code- neurons in different places in the body signal different qualitative features Temporal Code-neurons can fire quickly and slowly -there is an upper limit to how fast they can go -different neurons fire at different speeds -frequency of a sound perceived as pitch can be coded in the firing rate of a group of neurons -loudness and brightness is coded in firing rate Spontaneous Rate- rate of neuronal firing when no stimulus is present Rate of Firing- codes the intensity of a stimulus Multisensory- relating to or involving more than one physiological sense Cranial Nerves- senses information travels along it through holes in the skull- a protective bony case The Visual World The Human Eye -senses array of information, then relays it back to the brain for complex perceptual processing Light-radiation that occupies a relatively narrow band of electromagnetic spectrum -stimuli -Travels in waves that vary in terms of: -length -amplitude -receptor is the light-sensitive structure in the back of the eye Wavelength-distance between peaks of a wave -differences between them correspond to different colors on the electromagnetic spectrum -long wavelengths-> reddish colours -short wavelengths-> bluish colors Amplitude-peaks of a wave gives different experiences -Low-amplitude waves-> dim colors -High-amplitude waves-> bright colors -we see a mixture of wavelengths that vary in hue (colors of the spectrum), intensity (brightness), and saturation (colourfulness or density) -we don’t typically see such pure coloration -sensitive and delicate, needs physical protection -structures function to regulate the amount of light that enters the eyes, and organize light into a pattern that the brain can interpret Sclera- white, outer surface of the eye Cornea-clear layer that covers the front portion of the eye -contributes to its ability to focus -light passes through it to get to the pupil Pupil-regulates the amount of light that enters by changing its size -dilates to allow more light to enter and constricts to allow less light into the eye Iris-round muscle that adjusts the size of the pupil -gives the eye their characteristic color Lens-clear structure that focuses light onto the back of the eye -behind the pupil Retina-lines the inner surface of the eye and consists of specialized receptors, photoreceptors, that absorb light and send signals related to the properties of light to the brain -Two types of photoreceptors: -Rods-occupies peripheral regions of the retina -highly sensitive under low light levels -Cones-sensitive to the different wavelengths of light that we perceive of color -Fovea- central region of the retina that contains the high concentration of cones -explains why objects in our direct line of vision are the clearest -in light it’s more active than rods -moving away from the fovea, causes the concentration of cones to decrease and the concentration of rods to increase Dark Adaption-process where rods and cones become increasingly sensitive to light under low levels of illumination -explains why we gradually see more objects in low light levels Purkinje Shift-eye’s sensitivity to different hues to change with the transition from cone to rod vision -Bright sunlight- cones are active and rods are inactive, and cones are most sensitive to yellow and red -twilight- rods are more active and cones less sensitive, rods cant process color, but is most sensitive to light with a wavelength that we perceive as yellow-green Photopigments-complex molecules found in photoreceptors that generate electrical signals in the photoreceptor when they are exposed to light -exposure to light causes a change in chemical structure, gradually becoming white, Bleaching, which generates a neural impulse and a photoreceptor to become less receptive to light, when it is fully white, it stops processing -Four types in a retina: -long-wavelength cones or red cones -Medium-wavelength cones or green cones -Short-wavelength cones or blue cones -Medium-wavelength rod -> different than green cones Additive Color Mixing-creating new colors by adding together coloured lights -white light is obtained when lights of many different wavelengths are mixed together, the more wavelengths the whiter the light Subtractive Color Mixing- mixing different paint pigments together Trichromatic Theory of Colour Vision-Young and Helmholtz -colour vision is the result of activity of three different colour receptors in the retina -Wald discovered the three different types of rods Opponent Process-coding of colour or brightness by the relative activity in two photoreceptor populations -Ewald Hering agreed with Helmholtz that there are three types of color detectors but believed they were opponents (red vs. green, blue vs. yellow, and black vs. white) Resolution-size of the smallest difference that can be identified -higher resolution means that a smaller difference in location, color, amplitude, or other attribute can be detected or distinguished. Optic Nerve-cluster of neurons that gather sensory information, exit at the back of the eye, and connect with the brain -Travels through the back of the eye and creates an area on the retina with no rods or cones- optic disk- a blind spot, where the brain fills in the blind spot with the vacancy of yellow Nearsightedness-eyeball is slightly elongated -image that the cornea and lens focus on to falls short of retina -can see objects that are relatively close but have difficulty focusing on distant objects Farsightedness-eyeball is shorter -image is focuses behind the retina -can see distant objects but not close by -visual impairment can be corrected with contact lenses or glasses Optic Chiasm-where the optic nerve crosses the midline of the brain -half of nerve fibres travel to one side of the brain, and the rest the other side -fibers connect with the visual area of the thalamus at a region called the Lateral Geniculate Nucleus (LGN)- sends messages to the visual cortex, located in the occipital lbve, where the complex process of visual perception begin -for the visual cortex to understand information, it divides labour among specialized cells -Feature Detection Cells- respond selectively to simple and specific aspects of a stimulus Auditory System -function of the ear is to gather sound waves-> stimulus -function of hearing is to inform you about the nature of the sound source -transduction of sound takes place in a specialized structure -results from vibration of adjacent air molecules to become compressed into local regions of increased pressure, and rarefied in local regions of decreased pressure which changes travels through the air to our ears in a wave -receptor is the hair cells that respond to pressure changes in the ear Sound Waves-changes in mechanical pressure transmitted through solids, liquids or gases -Two characteristics: -Frequency-wavelength measure in hertz (Hz), the number of cycles a sound wave travels per second -Pitch-perceptual experience of sound wave frequencies -High-frequency sounds have short wavelengths and a high pitch -Low-frequency sounds have a long wavelength
More Less

Related notes for PSYC 100

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.