Psych/Soc Series: Hearing, Weber’s Law and More

Session 84

This is week one of our Psych/Soc series on the MCAT Podcast. We’re covering some biology questions which is a subject covered in the Psych section of the MCAT. A lot of students struggle with this section because they’re very specific on what you need to know.

Bryan Schnedeker from Blueprint MCAT (formerly Next Step Test Prep) is here, as always, to help us break down these questions for you so you can crush your MCAT come test day! Also make sure to take a listen to all our other podcasts on MedEd Media Network.

[02:44] Bio Questions on Pysch/Soc Section

Several students have actually been surprised to see biology questions in the Psych/Soc section. They fall for that trap of thinking that all they have to do is study these high yield topics and they’re good to go. But remember that with the sole exception of amino acids, there’s really no such thing as a high yield topic. If you want to do well on any of the science questions, you’ve got to know everything. You’ve got to really cover your bases.

[03:23] Ear Questions

Question 1: Which sequence best describes the pathway used to transmit auditory information in humans?

(A) Cochlea > Organ of Corti > Medial Geniculate Nucleus > Auditory Cortex
(B) Organ of Corti > Cochlea > Auditory Cortex > Medial Geniculate Nucleus
(C) Cochlea > Organ of Corti > Auditory Cortex > Medial Geniculate Nucleus
(D) Organ of Corti > Cochlea > > Medial Geniculate Nucleus > Auditory Cortex

Bryan’s Insights:

Luckily, I guessed A right and Bryan says it was a “textbook-perfect” reasoning for the MCAT. You use one fact to narrow it down and then eliminate stuff that was the same with the remaining answer choices.

[05:22] Weber’s Law

Question: Weber’s Law can be applied to:

(A) Sound as when a constant 30 decibel tone in an individual’s ear
(B) Weight as when two study participants each hold a steel bar that have different masses.
(C) Visual stimuli as when a man attempts to distinguish between images at different brightness levels
(D) A, B, and C – all of the above are true

Bryan’s Insights:

Weber’s law is also called as the “just noticeable difference” which means that if I present to you two different stimuli, will you say, that’s the same thing or that this stimulus is more or less intense than the other stimulus.

For A, it doesn’t work since you have to have two different tones to detect the different loudness of those two tones. B doesn’t work either since it’s two different participants are each holding their weight. But Weber’s law is about a single person distinguishing between two different stimuli. This means that that the right answer here is C since there’s one observer and two different stimuli. Can the person tell the difference? And that’s Weber’s law.

So theoretically, it can be anything that the human organs of sensation can attempt to distinguish between. The basis of Weber’s law says that the differences are proportional, not absolute. So this could be touch, pressure, weight, vibration, sound, brightness, color – literally anything that you can distinguish between. The idea here is that if you were given two different objects, each of which weighs less than half a pound. And if one is 10% heavier than the other, you’ll be able to tell the difference. Even though that 10% might only be a couple of ounces, you will be able to tell it.

Then you could be given two enormous blocks, one of which weighed 30 pounds and the other weighed 32 pounds. It’s a two-pound difference. With the little weight, you were able to tell two ounces, of course, you can tell two pounds. But Weber’s law says you can’t. Because you picked up the 30 and then you lean over again. Lift with your legs, not with your back. And then you scrunch down and pick up the 32. And you would say they’re the same as each other because the difference between them is less than a 10%. So Weber’s law is not absolute, but it’s proportional differences that we notice.

[09:23] Sensory Adaptation

Question 4: Which of these scenarios exemplify the process of sensory adaptation?

(A) A steel worker wears a thicker gloves after noticing calluses on his hands.
(B) A flight attendant gradually overcomes his fear of heights as his flight hours increase.
(C) A pastry chef begins to stop noticing the appetizing and distracting smell of pastries in her kitchen.
(D) A child starts to associate the smell of her dog with affection rather than fear.

Bryan’s Insights:

Remember when you say sensory, it’s the raw data inputted into your face. As opposed to perception, which then starts to involve higher cognitive processes, what to choose to pay attention to, and your cultural preconceived notions. So perception operates on a much higher level. Sensation is a very kind of raw, biological, mechanical thing.

So sensory adaptation is just an unconscious process. The relevant organs just stopped responding to a particular kind of stimulus. Unlike the child who starts to associate the smell of the dog with comfort rather than fear, you see the association. And that’s a learning process. It’s not just an unconscious adaptation While the pastry chef just stops smelling the food in the kitchen since there’s just less response from the relevant sense organs.

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