Sensation, Perception and Consciousness Flashcards
What is sensation?
The physical stimulation of the sensory apparatus
I.e. pressure on skin, vibrations on ear drums, etc.
What is perception broadly?
“The faculty of percieving”…“the ability of the mind to refer to sensory information to an external object and its cause”. (OED, 1994, p. 1077)
The experiential component of sensation
Vision (Sight)
One of the classic 5 senses
Primary receptor: Eye - light receptive ganglion cells in the retina
Stimulus: Light - Electromagnetic wave forms
Audition (Hearing)
One of the classic 5 senses
Primary receptor: Ear - Timpanic membrain (ear drum), organ of corti, hair cells
Stimulus: Changes in air pressure (Reverberation/Vibration)
Somatory sensory/Haptics (Touch)
One of the classic 5 senses
Primary receptor: Skin - Various mechanoreceptors
Stimulus: Mechanical pressure/deformation of the skin, changes in temperature
Gaustation (Taste)
One of the classic 5 senses
Primary receptor: Tongue - Taste buds in the papillae
Stimulus: Chemical substances dissolved in saliva
Olfaction (Smell)
One of the classic 5 senses
Primary receptor: Nose - Cillia in the mucus layer of the epithelium situated at the top of the nose and back of the throat
Stimulus: Airbourne substances dissolved in the mucus layer
Which sense is associated with the Primary Auditory Cortex
Hearing
Which sense is associated with the Primary Sensory Cortex
Touch
Which sense is associated with the Primary Visual Cortex
Vision
Which sense is associated with the Amygdala and Hypothalamus
Taste
Which sense is associated with the Pituitary Gland
Smell
How is information processed, broadly?
- Sensory information is captured (i.e. light, sound, etc.)
- It is converted to electrical energy
- It is carried along multiple specialized routes
- It is processed in multiple locations for different purposes
- We experience a coherent whole
What is perception, more specifically?
Perception is accessing and capturing the outside world, transforming it and representing it in the brain
It is about making sense of the world (forming a cohesive whole)
Perception is adequate (Matlin & Foley, 1992) but not accurate (Ventriloquist Effect; McGurk Effect)
Ventriloquist Effect - TV
An example of the inaccuracy of perception
It appears that voices come from people on the TV screen rather than the speakers
McGurk Effect
An example of the inaccuracy of perception
Why are there inaccuracies in our perception, broadly?
We do not process everything, and not everything we process is explicit/conscious
Matlin & Foley (1992)
Perception is adequate because:
1) Physical stimuli is rich in information
2) The human sensory system is very good at gathering information
3) Concepts shape our perception
- Our experiences and expectations influence our perceptions
What is consciousness?
Consciousness is your individual awareness of your unique thoughts, memories, feelings, sensations, and environment
Bor & Seth (2012)
Distinguises between:
1) Consciousness level - Scale of awareness from zero contents to fully aware
2) Consciousness content - Moment to moment, here and now experience
Baumiester & Masicampo (2010)
Difference between levels of content experience in consciousness:
Low-level: Basic here and now (all animals)
High-level: Reasoning, self-reflecting (humans only)
David Chalmers (2007)
Two problems of consciousness:
1) Easy (soft) problem - Where does it come from?
2) Hard problem - How/Where?
Our ability to choose/free will appears somewhat artificial
Easy (soft) problem of consciousness
Where does it come from?
Consciousness comes from brain activity
Activity in the brain for stimuli that we process both with and without awareness, and can respond to, is different but present
Hard problem of consciousness
How/Where?
How does brain activity actually become conscious awareness?
Where does the experience come from?
Why are we conscious at all?
Limit of perception and awareness - (Koch & Tsuchiya, 2007; Lamme, 2003)
Consciousness and attention are not the same thing but they are related
When are we conscious? - (Merikle, 2001)
Subjective (self-report) threshold (limit) = Point at which individuals can/cannot report awareness of a stimulus
Objective (observer) threshold = Point at which individuals can/cannot make accurate forced choice decisions about a stimulus
This is what psychologists measure
Global Workspace Model - Baars (1988;97), Baars & Franklin (2007)
We process more than we are aware of:
- Selective attentional processes (filtering, augmenting, etc.) affects how much of what we process we are aware of
- What we see of hear is selected
Consciousness comes from synchronised and integrated activity across multiple brain regions (including prefrontal cortex, anterior gyrus, and parts of the parietal lobe)
Support for the Global Workspace Model (Gaaillard et al., 2002; Lamy et al., 2009; Melloni, 2007; Rees, 2007)
ERP and fMRI evidence supporting differential brain activity for objects (words) that are below conscious perception
Behavioural results suggest unconscious processing is possible up to and including semantic level
(Response affected by meaning of the target even though you did not see/hear it)
Different patterns of activity seem to occur around the different points of the suggested network
Limitations of the Global Workspace Model
Zero level of consciousness is difficult to define and likely impossible to measure (Lamme, 2003)
Vegatitve states and sleep
- Even patients with limited brain activity appear to have some level of awareness
- We respond to stimuli, and might even be able to leanr, in our sleep
No explanation of how or why we are conscious
The Binding Problem
If incoming information is extracted and broken down, how is it then put back together?
(Feldman, 2013)
Feldman (2013)
Multiple Difficulties (The binding problem)
We do not really have an answer,
We do have these theories:
1) Some of the information is not broken down and maybe it doesn’t matter at an unconscious level
2) Synchrony (See card)
3) Weak structural functionalism (See card)
4) Selective attention (See card)
5) Gestalt - Pragnanz (See card)
Synchrony (consciousness)
a) Precise synchrony: Use timing of single cell firing to time-stamp info (problem - this is computationally expensive)
b) General synchrony: General pattern of cell firing is used to bind (problem - loss of detail)
Consciousness may come from synchrony and coordination
Weak Structural Functionalism (consciousness)
Some ‘cells’ do multiple tasks
- The same region of the brain might do more than one job, e.g., pitch/frequency and timbre
Selective Attention (consciousness)
Attentional clusters (grouping)
We attend (process) things/events together so they are bound in the brain
Gestalt - Pragnanz
Laws (biases) for putting information together in a coherent way
For example:
- Similarity: similar things go together
- Proximity: close together things go together
- Good continuation: when an object intersects you assume the intersected object continues
Why are we conscious? - Perceptual
Percieving your environment may help you better interact with it (although this is an unlikely reason)
Why are we conscious? - Social communication
For understanding and interacting with others (theory of mind)
Problem: What about other animals?
Why are we conscious? - Action control
For free will, control and agency
This is very unlikely though
Why are we conscious? - Information integration
To reflect your own experience - allows you to integrate experiences as you have them
Sensation (Summary)
Sensation = Detection
Information is captured by the sensory systems and converted to neuronal activity
Information is broken down, extracted, analysed, and put back together
Perception (Summary)
Perception = Experiencing
How we get from sensation to perception is unclear but it seems to be a combination of top-down and bottom-up processes
Not all of it is lost
Consciousness (Summary)
Hard (how and why) and Easy (how) Problems
Limits of perception, consciousness and awareness
Global Workspace - selective awareness
Binding problem and the function of consciousness - we don’t know how we put it all together or why we do and what it is for
