Slides Week 1 Flashcards
Sensation
The ability to detect a stimulus and to turn that detection into a private experience.
Perception
The act of giving meaning to a detected sensation.
Perception
The act of giving meaning to a detected sensation.
Transduction
- Converting from one form of energy to another.
eg: converting light into action potentials in the brain
Step 1: Activate environmental stimulus
Step 2: light is reflected and transformed
Step 3: Receptor processes begin
Where is perception in the 7-Step model?
- Step 5
- Neural processing takes place in the circuits of the eye and brain
- Signals are then sent to different areas of the brain. Step 3: Receptor processes
Step 4: Neural Processing
Step 5: Perception
Occipital Lobe
Responsible for Vision
Parietal Lobe
Responsible for Skin Senses
Transduction
- Converting from one form of energy to another.
eg: converting light into action potentials in the brain
Step 1: Activate environmental stimulus
Step 2: light is reflected and transformed
Step 3: Receptor processes begin
Perception in the 7-Step model
Step 1: Activate environmental stimulus
Step 2: Light is reflected and transformed
Step 3: Receptor processes stimulus
Step 4: Neural Processing
Step 5: Perception
Step 6: Recognition
Step 7: Action
Occipital Lobe
Responsible for Vision
Parietal Lobe
Responsible for Skin Senses
Frontal Lobe
Responsible for Problem Solving and thinking
Temporal Lobe
Responsible for Hearing
The Perceptual Process
- The 7-Steps of perception
- Sensation and perception are vital to nearly all of human behaviour and thought,
Psychophysics
The science of defining quantitative relationships between physical and psychological events
Thresholds of Sensation
Sense: Threshold
Vision: Stars at night, or a candle flame 50 km away
Hearing: A ticking watch 6 meters away
Vestibular: A tilt of less than half a minute on a clock face
Taste: A teaspoon of sugar in 8 litres of water
Smell: A drop of perfume in 3 rooms
Touch: The wing of a fly falling on your cheek from 10cm
Absolute Threshold
The minimum amount of stimulation needed for a person to detect a stimulus 50% of the time
How do researchers know if a participant can sense a stimulus?
By using different methods of measuring perception
- Method of Constant Stimuli
- Method of Limits
- Method of Adjustments
Method of Constant Stimuli
Participats respond to a range of stimuli that are rarely to always perceivable
Method of Limits
Stimuli is incrementally varied until the participant can detect it.
Method of Adjustment
Participant will adjust the stimuli till they can detect it.
JND
- Just Noticeable Difference
- The smallest detectable difference between two stimuli
- Weber’s Law
- A standard weight stays the same through and experiment
- A comparison weight differs over a series of trials in an experiment
Weber’s Law
- The JND is a constant fraction of the comparison
- Standard weight stays the same over a series of experimental trials.
- Comparison weight differs over a series of experimental trials.
Fechner’s Law
- Extends on Weber’s Law
- Subjective sensation increases proportionally to the logarithm of the stimulus intensity.
Steven’s Power Law
- If we double the intensity of a light, does it look twice as bright?
- The magnitude of subjective sensation is proportional to the stimulus magnitude raised to an exponent
Definition: Exponent
- a number shown as a superscript of another number to indicate how many times the base number is to be multiplied by itself.
Cross Modality Matching
- The ability to match the intensities of sensations that come from different senosory modalities
- A variation of the magnitude estimation method allows for cross modality matching
Signal Detection Theory
The detection of stimulus depends on a person’s sensitivity (d’) to the stimulus and the person’s response criterion
Odourant
A molecule capable of being translated into the perception of smell by the nervous system
Odour
The translation of a chemical stimulus into a smell sensation
The Chemical Senses
- The Olfactory System
- The Gustatory System
Olfactory Cleft
A narrow space at the back of the nose containing the olfactory epithelium
Olfactory System
- Olfactory Cleft
- Olfactory Bulbs
- Olfactory Epithelium
- Turbinates
- Glomerulus
- Primary Olfactory Cortex
- Orbitofrontal Cortex
Olfacatory Bulbs
Olfactory Epithelium
- Where neurons receive sensory input
- called olfactory sensory neurons
- Translate input into neural firing
- Contains ~5-10 million olfactory sensory neurons
When does olfaction begin?
When an odourant enters the nose and travels to the top of the nasal passage where the olfactory epithelium is located
Olfaction
the action or capacity of smelling; the sense of smell.
Turbinates
Small ridges inside the nose that add turbulence to sniffed air before it reaches the oflactory cleft and olfactory epithelium
Glomerulus
A cluster of incoming axons of the olfactory sensory neurons
Primary Olfactory Cortex
- The brain region where olfactory information is first processed
- Projects to the Orbitofrontal Cortex both directly and via the amygdala
Shape Pattern Theory
- The fit between a molecule and an olfactory receptor determines what pattern of neural activation occurs
- In theory we can detect 1 trillion colours
What is Odour Perception dependent on?
-
How Experience changes the brain activation
- Wilson, Best & Sullivan 2004
-
Odour Hedonics (Engen 1982)
- Learning what smells we like
-
Olfactory Associative Learning
- If the context of the odour is good, the odour will be liked
- if the context of the odour is bad the odour will be disliked
- Receptor Adaptation
- After continual exposure receptors stop responding
-
Cognitive Habituation
- After long term exposure one does not detect an odour.
Odour Hedonics
- Odour Hedonics (Engen 1982)
- Learning what smells we like
Olfactory Associative Learning
- If the context of the odour is good, the odour will be liked
- if the context of the odour is bad the odour will be disliked
Receptor Adaptation
After continual exposure receptors stop responding
Cognitive Habituation
After long term exposure one does not detect an odour.
Olfactory Sensory Neurons
- Modified Neurons specific to olfaction
- Found in the olfactory epithelium
- send action potential to olfactory bulb
Androstenone
- is a steroidal pheromone.
- It is found in
- boar’s saliva
- celery cytoplasm
- truffle fungus.
- human sweat
- saliva
- Androstenone was the first mammalian pheromone to be identified
*
Factors that affect our sense of smell
- Genetics (number and type of OSNs)
- Experience
- Cultural norms
- Gender
- Age
Tip of the Nose Phenomenon
- Linguistic Processing is disconnected from olfactory experience
- New findings are throwing this into question
- A special area of the thalamus is involved in olfactory processing
- South Asian tribes have demonstrated comprehensive vocabulary and identification of smells
Smells and Memory
- Memory for a smell is long lasting and stable over time. (Engen, Kuisma & Eimas 1972)
- Smells tend to produce more emotionally intense memories (Chu & Downes 2002)
- Memories triggered by odours also activate the amygdala
- Memories are triggered less by other senses
What is olfaction used for?
- Warning of impediment
- spoiled food
- smoke
- noxious gas
- Detection of food
- works with other senses to detect taste
- Scent Tracking
Pheremones
Chemicals emitted by a member of a species that triggers physiological or behavioural responses in another member of a same species.
Androstadienone
- An endogenous steroid described as having potent pheromone like qualities in humans.
- Has been added to male scents and marketed as a deoderant to make men more sexually appealing to women.
Chemosignals
- Signals released by humans that are detectable by the olfactory system
- have an effect on mood, behaviour, hormonal status and sexual arousal of other humans
Smelly T-shirt Experiment
- measured MHC-dependent mate preferences in humans.
- MHC influences both body odours and body odour preferences in humans.
- suggests that the MHC or linked genes influence human mate choice today.
Miller & Maner (2010)
Men are more likley to come up with sexual words when smelling T-shirt of an ovulating woman.
Gelstein et al. (2011)
Found women’s tears reduce sexual desire in men.
Is smell of psychological interest?
- Pleasant odours increase positive mood and decrease anxiety (Villemure et al., 2003; Riello et al., 2019)
- Pleasant odours are associated with increase in charitable behaviour (Baron, 1997)
- Changes in olfaction can be early detectors for psychosis, schizophrenia, Parkinsons & Alzheimers (Good, 2015)
- Poor odour identification is a predictor for poor outcommes for schizophrenia (Good et al., 2010)
Define Taste
Sensations evoked by solutions in the mouth that contact receptors on the tongue and the roof of the mouth
Flavour
- The Combination of true taste:
- sweet
- salty
- sour
- bitter
- and retronasal olfaction
Retronasal Olfaction
- The ability to perceive flavor dimensions of foods and drinks
- Retronasal smell is a sensory modality that produces flavor
- It is best described as a combination of traditional smell (orthonasal smell) and taste modalities.
Gustatory System
Detects molecules that we put in our mouths and allows for the sense of taste.
Retronasal Olfactory Sensation
- The sensation of an odour perceived when chewing and swallowing
- This forces odourant in the mouth up behind the palate into the nose.
- Without smell the ability to identify foods by ltaste alone is poor (Mozell et al., 1960)
Taste Bud
A Cluster of cells that convey neural signals to the brain by the taste nerves
Taste Receptor Cell
- A cell with the taste bud that contains sites that can interact with charged particles and chemical structures
Fungiform Papillae
- Mushroom shaped structures
- Distrubuted most densley on the edges of the tongue
- Mostly located on the tip of the toungue
- Taste buds are buried in the surface
Circumvallate Papille
- Circular structures that form an inverted V on the rear of the tongue
- Mound like structures are surrounded by a trench
- Taste buds are buried in the sides of the trenches
Foliate Papillae
- Folds of tissue containing taste buds
- Located on the rear of the tongue lateral to the Circumvallate Papillae
Papillae
- small, round or cone-shaped protuberances on the top of the tongue that contain taste buds.
Types of Papillae
- Circumvallate Papillae
- Foliate Papillae
- Fungiform Papillae
The Bogus Tongue Map
- All taste qualities are found in all areas of the tongue (Huang et al, 2007)
- Different types of taste receptors are responsible for different tastes.
The Gustatory System
- After leaving the taaste buds, taste information travels through the medulla and thalamus
- Information travels to the Insular Cortex
- The Insular Cortex projects onto the Orbitofrontal Cortex
Taste: Salty
The taste quality produced by the positive charged ions of salts
Taste: Sour
The taste quality produced by the hydrogen ion in acids
Taste: Sweet
The taste quality produced by some sugars such as glucose, fructose and sucrose
Taste: Bitter
The taste quality generally considered unpleasant produced by substances like quinine or caffeine
Taste: Umami
- Umami = delicious savoury taste
- Monosodium glutamate (MSG) produces pure umami sensation
- tends not to be palatable in itself
- combined with certain odours and saltiness leads to pleasant taste sensation (Rolls, 2009)
- May indicate prescence of proteins
- May require specialised taste receptors
- L-glutamate receptors
- Receptors for amino acids
Anosmia
- Inability to smell
- Approx 1 in 20 Americans
- Olfactory processing may have a complex relationship with depression (Croy et al., 2014; Herz, 2007)
Aguesia
- Inability to taste
- Approx 1 in 100 Americans
- Taste dysfunction may lead to poor diet choice
- related to disease prevention, obesity and well being
Supertasters
- Term refers to people who reported powerful bitter taste when tasting propylthiouracil (PROP) was placed on their tongues
- Supertasters have high sensitivity to PROP
- Hayes et al. (2008) found both genotyp and number of fungiform papillae contribute to being a supertaster
- Non-Tasters are not able to detect PROP
- Non-Tasters are ~1/3 of the population
Is taste of psychological interest?
Eriskine et al., 2011
- Taste can influence moral judgements; bitter tastes elicit feelings of moral disgust
Is taste of psychological interest?
Noel & Dando, 2015
- Mood can influence taste perception
- Positive emotions enhance sweet and diminish sour tastes
Is taste of psychological interest?
Pepino & Menella, 2005
- Sweet tasting solutions reduce pain in infants
- Some evidence suggests this continues throughtout childhood into adulthood
Is taste of psychological interest?
Kampov-Polevoy et al., 2004
- There is a link between preferences for sweet tast and alcohol and cocaine use
- Taste may be used as a predictor for subsance use disorders
