Sensory Coding & Capability: Modalities, Energies, Attributes & Objects

Remember  “Actions of Perception” ?? detection – is something there? location – where is it ? duration – how long does it last? intensity – how “strong” is it ? pain – is it “strong enough” to “hurt”? identification – what is it? categorization – what kind is it? enumeration – how may are there? discrimination – are two things the same or different? similarity/dissimilarity –how are different things different?

Remember  Sensory Processing ?? Transduction Brain Transduction – translation of stimulus energies that arrive at the sensory receptors into neural code modality-energy specific energy must be supra threshold Transmission Transmission – passive delivery of the neural code to the brain Brain -- where neural codes from different modalities are combined with memory, expectation, affect to produce final “perception” Processing Processing – a vast amount of processing is done – changing or augmenting the neural code, before it reaches the brain

Law of Specific Nerve Energies Different sets of receptors and nerve fibers are dedicated to each sensory modality same kinds of neural signal used for all modalities different kinds of receptors for different modalities different kinds of energy for different modalities different parts of the brain for different modalities same kinds of object information supplied from multiple modalities

Have to appreciate… All modalities are “touch” modalities !!!! For all modalities, sensation starts when a stimulus/energy “touches” a receptor! What touches where? Touch? Taste? Smell? Hearing? Vision?

Location of receptors? Sensations/Attributes ? Type of Stimulus Energy ? Let’s spend some time on what stimulus information is conveyed by what energies via what modalities… Important – notice the multimodal nature of perception?

So … the “Law of Specific Nerve Energies” explains how sensory reception, transmission & brain processing differ across modalities… What about the different kinds of information processed within a modality too ??? Does the “Law of Specific Nerve Energies” explain how different kinds of “information” are conveyed within a modality???

Some seem pretty simple (to start) … Taste – are sweet, salty, sour, etc perceived via different sensory cells? conveyed via different nerves processed in separate parts of the brain Touch – are shape/size, texture, compression, temperature, etc perceived via different sensory cells? conveyed via different nerves processed in separate parts of the brain What is the difference between the “kinds of information” we’ve isolated in these two examples? What is the problem here for us and our understanding of of how sensory information is conveyed ?????

What are the alternatives for within-modality processing ? “Sensory Coding” – within-modality processing different kinds of energy for different information different kinds of receptors for different information same electrical nature of neural signal used for all information different electrical/neural coding (freq, spacing, etc) same neural paths for different information same parts of the brain for different information “Law of Specific Nerve Energies” – within-modality processing different kinds of energy for different information different kinds of receptors for different information same electrical nature of neural signal used for all information same electrical/neural coding (freq, spacing, etc) different neural paths for different information different parts of the brain for different information

But it gets complicated… same kinds of neural signal used for all information Gonna be a problem – gets complicated quickly – consider “intensity” (freq & spacing both carry info) same of receptors for different information Reconsider taste What about touch  kinds of info = kinds of receptors ? What about vision  kinds of info = kinds of receptors ? different kinds of energy for different information Remember we decides all senses are “touch senses” different parts of the brain for different modalities Remember that “what part of the brain processes what information” seems a complex combination of … “where the info is coming from” (brain surface) “what information is being processed” (brain depth)

So, what to watch for as we work through the different modalities and kinds of sensory information … Across modalities  Doctrine of Specific Nerve Energies Within modalities  complex combination of “Specific Nerve Energies” & “Sensory Coding” AND….. Where & how do the top-down processes work into this????

Let’s think beyond humans… When thinking about “what animals can do perceptually that humans can’t” it is important to differentiate between: What animals do “like humans but better” enhanced capabilities with the same energies What animals do differently than humans” energies that humans can’t work with

Let’s think about human’s a bit differently… We live in a pretty “cushy” world … We tend to think of perception as Communication Entertainment Our species has/does not always had it so easy! Sometimes perception is about being … The predator … what information do we need to take in to find things to eat??? How do we get close enough to eat??? The prey … what information do we need to take in to not be eaten??? How do we stay far enough away to not be eaten???