Sensing And Perceiving Flashcards
Sensation
Response of our sense organs to stimulation by the outer worl
Perception
Act of organizing and interpreting sensory experience
How our psychological world represents out physical world
Sensory adaption
Sensory sensitivity diminishes when our senses are constantly stimulating
Ensures that we notices changes in stimulation more than stimulation itself
Acts as a filter to direct our attention to most relevant sensory information
Transduction
Conversion of physical into neural information
Once we know that a physical stimulus is something to attend to, the sense organs convert it into action potentials
Psychophysics
Study of how people psychologically perceive physical stimuli
Absolute threshold
Lowest intensity level of a stimulus we can detect half of the time
-smallest object you can see from a distance or softest sound you can hear etc
Signal detection theory
Takes into account both stimulus intensity and the decision making processes people use in detecting stimulus
Difference thresholds
Smallest amount of change between two stimuli that a person can detect half of the time
Aka just noticeable differences, where the size of the JND is a constant fraction of the intensity of the stimulus - Weber’s law
Bottom up processing
Building a perceptual experience from basic elements of sensation
Top down processing
Perception of the whole guides perception of smaller elemental features
Eg. Our frame of mind, which is ultimately coded in the brain can impact how we perceive things
Perceptual set
The effect of frame of mine on perception
Function of the eye
Bends light, converts light energy to neural energy, and sends that info to the brain for further processing
Most of our visual experience happens not in the eye, but in the brain
Cornea
A clear hard covering that protects the lens
Where light enters the eye
Pupil
Where light entered the interior of the eye
Iris
Coloured part of the eye
Adjusts the pupil to control the amount of light entering the eye
Lens
Light passes through
Bends the light rays to allow the large area of visual space to be represented in the much smeller area of the eye
Retina
Thin layer of nerve tissue that lines the back of the eye
Muscles around the lens alter its shape depending on the distance of an object to allow it to focus light on the retina
Accommodation
Process by which the muscles control the shape of the lens to adjust to viewing objects at different distances
Eye and receptor cells
Light hits the retina and is processed first by the photoreceptors (rods and cones) the deepest layer
Then by the bipolar cells, which send it to the ganglion cells
Horizontal and a machine cells modulate the activity of the other cell types
Transduction occurs in the retina which is made up of neurons
Photoreceptors
Convert light energy into neural impulses and are located in the deepest cell layer
Only retinal cell responsive to light; other cell types are responsive to neurotransmitters
Ganglion cells
Most superficial layer
Ganglion cell axons form the optic nerve that carry information from the eye to the brain
Bipolar cells
2nd deepest layer
Form synapses with both ganglion cells and photoreceptors
Link the cells that transduce light stimulus with those that transit the information to the brain
Horizontal and amacrine cells
Located in an orientation perpendicular to the other cell types
Integrate the activity of the other cells
Horizontal cells located between photoreceptors and bipolar
Amacrine cells located between bipolar and ganglion
Rods
More numerous
Located mainly in the outer periphery of the retina
More sensitive to light (work well under low illumination)
Do not allow for finely detailed colour vision
Cones
Less numerous than rods
Mainly located in the fovea (area in the centre of th retina that corresponds to our central focus of visual space)
Allow for visual acuity
Visual acuity
Ability to see clearly
Depends on our cones
Light interacting with photoreceptors
Embedded in the cell membranes of rods and cones are proteins with light sensitive photo chemicals
When light interacts with these photo chemicals it results in a change in the shape of the protein
This in turn alters the flow of sodium across the photoreceptors membrane and alters release of neurotransmitter at the canapés with bipolar cells
Rhodopsin
Protein found in rod cells
Particularly sensitive to light
Under conditions of bright illumination, is is said to be bleached (inactivated protein) due to maximum stimulation
Photopsins
Protein found in cones
Less sensitive to light and do not bleach under bright light
Under typical daytime conditions we rely on cones
Allow us to see colour
Dark adaption
Process of adjustment to seeing in very dim light
Photochemicals in cones and rods readjusting to low illumination
Light adaption
Opposite of dark adaption
Suddenly exposed to bright light
Vision and the brain
Optic nerve transmits signals to the brain
Point at which the optic nerve exits the eye is called the optic disc (forms a blind spot on the retina)
Optic chiasm
Where the strand of optic nerve crosses to the opposite side of the brain
Lateral geniculate nucleus
A cluster of neuron cells bodies in the thalamus
Visual information creates a point by point representation on the tissue of the LGN
Fibres from LGN travel to the visual cortex in the occipital lobe
Receptive fields
Neurons in the visual cortex that are highly specialized for detecting specific regions of visual space
Feature detectors
Analyze the rental image and respond to specific aspects of shapes angles and movements
Simple cells: respond to very specific information such as a bar of light oriented at a particular angle
This Complex cells receive input from many different simple cells and are receptive to particular singular in different parts of the receptive field . Also sensitive to movement
Hypercomplex cells receive input from many complex cells and fire in response to patterns of lines
Auditory pathways
Auditory neurons transmit sound impulses to the thalamus in the brain.
Auditory pathways go from the cochlea to the inferior colliculus in the brain steam and from there to the medial geniculate nucleus of the thalamus and from there to the auditory cortex in the temporal lobe
Right auditory cortex
More active in processing non-verbal stimuli
Left auditory cortex
More active in processing speech and language
Bodily senses
Senses based in the skin, body or any membrane surface
Touch, temperature, pain, position/motion, balance, and interoception (perception of bodily sensations)
Mechanoreceptors
Receptor cells that are sensitive to different tactile qualities.
Psychogenic or psychosomatic pain
Feeling pain with no apparent tissue damage
Chronic pain or fibromyalgia
Sensitivity to tactile stimulation
Nociceptive pain
Pain from tissue damage
Pain receptors sensitive to heat, cold, chemical irritation and pressure are all types of nociceptors
Anterior cingulate cortex and insula
Active in both physical and emotional pain
Gate control theory of pain
Proposes that the spinal cord regulates the experience of pain by either activating or inhibiting neural networks called gates involved in pain sensations that get sent to the brain.
Opioids
Class of neurotransmitter that act as natural painkillers
Endorphins
Type of neurotransmitter that suppresses pain by interfering with pain messages in the spinal cord as well as the brain
Pain enhancement
Occurs under conditions of illness, when elevated pain signals are thought to be beneficial so that an organism can rest and recuperate.
Glial cells wrapped around axons enhance pain signals
Olfactory sensory neurons
Small area high in the lining of the nasal cavity
Receptors for smell
Contain cilia which convert chemical information in odour molecules into neural impulses
Olfactory bulb
When chemicals come in contact with receptors on the cilia, transduction occurs via changes in ion flow and the olfactory message travels to the olfactory bulb in the forebrain
Olfactory bulb sends info either directly to the smell processing area in the cortex or indirectly to the cortex by way of the thalamus
Primary olfactory cortex
In temporal lobe
Secondary olfactory cortex
Frontal lobe near the eyes
Orbitofrontal cortex
Region of brain most involved in flavour perception
Receives input from brain areas involved in olfaction and taste as well as from areas involved in touch and vision.
This is where signals from taste and smell meet
