Sensory Things!

Our new unit brings up a storm of new vocabulary & concepts. Many of them are difficult to understand. I want us to concentrate on the basics for now & in the spring we’ll get deeper into things. My previous post addressed some of the confusion that exists in the transduction-sensation-perception process. Now, let’s turn our attention to what happens when sensation reaches the brain.

I give you these possible blog post prompts:

  1. After reading through the material on sensory adaptation, I found myself wondering if it were the product of the receptor cells located in the sensory organs or a product of a certain part of the brain. Perhaps you could answer that question in your blog: what brain structure is responsible for sensory adaptation? There is only one right answer. You must use your knowledge of brain layers & structures to answer it though.
  2. As the textbook contains this question (p. 114), “Do you see why it’s not a good idea to listen to interesting music while you are studying?”  I like this question. Most of us have tried to study while listening to favorite music, but have been distracted. I find it easier to study in a slightly noisier & chaotic environment like a coffee shop or my study hall, but more difficult to study in silence, at home, or if it gets too  loud. My blog prompt for you: (a) what is the answer to the author’s question, (b) where is it easier for you to study? & (c) what is happening when environment mental noise becomes distracting? All three questions are essentially the same.
  3. We’ve looked at two aspects of thresholds so far, absolute threshold & difference threshold. Those are relatively straightforward in their meaning. However, when we get to signal detection theory, the author notes that “the classic theory of thresholds ignores the (perceiver)”. In a blog post, you could explore the relationship between perceiver & sensory thresholds. What aspects of your physical or mental condition or the environment have you noticed in your experience as a perceiver make a difference in your personal sensory thresholds?
  4. Lastly, the textbook covers subliminal persuasion on pages 116 – 117. What do you make of subliminal persuasion? Why is it included in a chapter on sensation & perception? What was convincing to you in the section?

I look forward to reading your thoughts on these issues or ones that I haven’t thought of yet! Surprise me with your insights & reactions this week.

Week 4 (7 – 11 Nov): From Stimulus 2 Perception

As I study the material in the textbook & read from other sources I continue to marvel at the lack of clarity between the four basic steps in process of transforming stimuli to perceptions:

Stimulus –> Transduction –> Sensation –> Perception

Stimulus is easy, right? That is the energy & substances & objects in our environment that we encounter and that match up with the receptor cells in our sense organs. Stimuli clear exist in the environment and outside of our nervous system.

Transduction, on the other hand, is where things get murky, but only just. Transduction, we are told, occurs when the receptor cells transform the stimuli into neural impulses. Again, it takes place in our sense organs, but outside of our nervous system… or does it? It ends with the firing of the nerve cell that is designed to be stimulated by the stimulus.

Sensation, though, is definitely steeped in murkiness. The textbook defines sensation as “the process by which stimulation of a sensory receptor produces neural impulses that the brain interprets…” But isn’t the production of a nerve impulse from transduction? When is the nerve impulse part of transduction and when is it part of sensation. The boundary is not clear to me. Are the receptor cells transducers of stimuli or are they sensors of stimuli? Is this just semantics? Will it make a difference on the AP exam?

Perception is definitely the murkiest! Perception is the process of making sensory patterns meaningful. That sounds pretty straightforward, right? I mean we interpret the patterns in the brain, but we’ve completed the brain unit so we can ask where in the brain is the boundary between sensation & perception. Aaah! MURK! Is the thalamus, that great relay station of sensory input, part of sensation or is it perception? Is the initial evaluation in the cerebral cortex sensation or perception. Is it only when other parts of the association cortex are involved that it becomes perception?

I’m definitely more comfortable when these things are clearly defined and delineated. Perhaps one reason there is this excessive amount of murk in this area is that psychologists & neurologists and their endless variations and allied fields are not yet sure.