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> Psychophysics and perception research is widely considered to be part of psychology ... Not according to the APA, nor how psychology is formally defined. ht

by lutusp 10y ago

> Psychophysics and perception research is widely considered to be part of psychology ... Not according to the APA, nor how psychology is formally defined. http://www.apa.org/support/about-apa.aspx?item=7 http://www.apa.org/support/about-apa.aspx?item=7 Quote: "Psychology is the study of the mind and behavior." > and has strong, falsifiable theories about how sensory stimuli are encoded and processed. Studies that aren't based on empirical evidence, that aren't based on theories about nature, cannot be falsified. We know a lot about behavior, but we have no empirical theories about it -- for that, we have to wait for neuroscience. > I'm not sure it suddenly becomes biology because someone later found the cellular substrate, nor did it become chemistry when someone figured out the structure of opsin. Of course it becomes biology/chemistry. But the connection between someone's ideas about the mind and biology can only be conjecture until neuroscience produces a physical theory that makes such a connection -- and at that point, mind studies will be abandoned. > ... also describes the mind's operation in testable and falsifiable ways. The mind is not a physical thing, consequently it cannot produce empirical evidence or falsifiability, two of science's fundamental requirements. If one psychological experiment asserts that X is so, and another asserts that X is not so, that's not a falsification, it's a contradiction. The difference? A contradiction can itself be contradicted in another experiment (something often seen in psychology), but a scientific falsification is conclusive. All this talk about empirical evidence, theories and falsifiability may seem overly philosophical until one realizes this is how we keep religion out of science classrooms.

mattkrause 10y ago
Let me give you an example, from visual perception. The "Feature Integration Theory" suggests that low-level image features are processed in parallel: you extract information about the color, orientation, and movement in parallel across the entire visual field. However, these representations are separate, and a second, serial process is needed to combine information across the two areas. This makes a specific, testable predictions. Suppose you're searching for a red triangle. If this shape is embedded in a sea of green triangles, your reaction time shouldn't vary as a function of the green triangles. The same thing should happen if the red triangle is surrounded by red circles--reaction times should be relatively constant regardless of the number of red circles. However, if you need to find a red triangle embedded in a mix of red circles and green triangles, you should a) be slower and b) your reaction time should be a function of the total number of shapes. I'd argue that this theory is empirical (run the experiment, record reaction times) and about as falsifiable as it gets (it's easy to test the difference in RT. vs. item # slopes). I'd also argue that this is a computational theory describing how visual search works, without worrying about the underlying implementation of that process. Clearly, it would be interesting to know that too, but it's certainly not necessary. David Marr proposed that cognitive processes could be studied on three levels: computational (what's the problem), algorithmic (what's a way to solve the problem), and implementation (what do the neurons do to run that algorithm), and each level was largely independent of the ones below.
- lutusp 10y ago
  You seem to be missing the point that, no matter how many hypotheses we make about the inner workings of the brain, we cannot turn them into science without either confirming or refuting them by direct examination of the brain itself. As long as we're hypothesizing about mechanisms that remain beyond direct observation, it's speculation. One cannot falsify a speculation. Psychology doesn't study the brain, it studies the mind. > I'd argue that this theory is empirical ... The observation is empirical but the theory isn't. It cannot become science without validation by way of empirical evidence. https://youtu.be/LIxvQMhttq4?t=32 https://youtu.be/LIxvQMhttq4?t=32 > I'd also argue that this is a computational theory describing how visual search works, without worrying about the underlying implementation of that process. Yes -- and because we cannot directly observe the processes we're hypothesizing about, we cannot make them a matter of empirical evidence, therefore we have no basis for falsification. https://www.britannica.com/topic/criterion-of-falsifiability https://www.britannica.com/topic/criterion-of-falsifiability Quote: "Criterion of falsifiability, in the philosophy of science, a standard of evaluation of putatively scientific theories, according to which a theory is genuinely scientific only if it is possible in principle to establish that it is false." > Clearly, it would be interesting to know that too, but it's certainly not necessary. Only necessary for science, otherwise not important.
  - mattkrause 10y ago
    On the contrary, the point I'm trying to make is that you can study the processing done by whatever's in your skull (mind, brain, GPU, nanobots, whatever) while being totally agnostic about the underlying hardware. You can develop theories about this, test them, falsify them, and revise them. Returning to the feature integration theory, it says that during singleton search (red vs. green), reaction times should be constant regardless of the number of items, while reaction time should be a linear function of the number of items when the search involves combining information from multiple feature channels. You can test this with a junky laptop or even some drawings and a stopwatch. In fact, if you really want, I'll send you a script so you can test it yourself. You can falsify this: just fit lines to the (item count, RT) data and see if the slopes match the predictions. People have, in fact, done this, and have shown that this explanation of visual search isn't quite complete--weird things happen when the target is very rare, for example. Can you explain exactly what some neuroscience data would add here? Look, I'm not some hardcore dualist. I work in a systems neuroscience group and completely agree that brain-based theories are more interesting than phenomenological ones, which is why I put up with the hours, pay, etc. However, this doesn't make those psychological theories any less valid, nor does it make psychology less of a science. Anyway, there are lots of other processes that are not directly observable. Gravity, for example, wasn't directly observed until last year. Evolution can't be observed directly either.
Y_Y 10y ago
> The mind is not a physical thing I was with you until here. I'd say you were getting religious if you tried to represent the mind as anything other than an emergent physical phenomenon.
- lutusp 10y ago
  > I'd say you were getting religious if you tried to represent the mind as anything other than an emergent physical phenomenon. A similar argument could be made from the opposite perspective. The mind is not part of nature, of reality. It's an artificial philosophical construct, arising from observations of behavior, and on that basis extrapolating the existence of something for which there's no direct evidence. Not unlike God in that respect. By definition, an emergent physical phenomenon would be something that ultimately emerged in physical form. The mind cannot do that. I think you're speaking of behavior, which does meet the definition.
  - mattkrause 10y ago
    I think you're putting a lot of weight on "study the mind" versus "study the brain." Not many psychologists are dualists. They tend to say "mind" because they want to abstract over the actual hardware--they're interested in studying what happens in the skull, not how it is implemented. This doesn't make it any less scientific than a biologist who studies where birds fly while neglecting the aerodynamics of the birds' wings.
    - lutusp 10y ago
      > They tend to say "mind" because they want to abstract over the actual hardware--they're interested in studying what happens in the skull, not how it is implemented. Yes, but asking what isn't science by itself, which tries to say how a particular observation came about. Also, psychologists don't really know what's happening inside our skulls. Studying the mind can't tell us what the brain is doing or how, any more than a computer display can tell us how a CPU works -- for the latter, we need access to the source, not its external manifestation. * If I say, “The night sky is filled with tiny points of light,” I've offered a description. Another observer might contradict my description, for example by emerging from his cave on an overcast night and not seeing any points of light, but the contradicting observation can itself be contradicted on the next clear night, without any chance for resolution. So, apart from being shallow, inconclusive and trivial, it's not science. * If I say, “Those points of light are distant thermonuclear furnaces like our sun,” I've offered an explanation, one that makes predictions about phenomena not yet observed and that's falsifiable by empirical test. On the basis of this explanation we might build a small-scale star (a fusion reactor) to see if our experiment shows any similarity to the spectra and behavior of stars. This deep explanation represents a theoretical claim that's linked to other areas of human knowledge, predicts phenomena not yet observed and is conclusively falsifiable by comparison with reality (our fusion reactor might fail to imitate the stars). It's science. > This doesn't make it any less scientific ... But it does -- one cannot falsify an observation, one can only contradict it. > This doesn't make it any less scientific than a biologist who studies where birds fly ... If the biologist only records where the birds flew, it's not science. If he crafts a testable, falsifiable theory about why the birds flew there, that might be science. Science is about crafting theories that go beyond simple observation, that explain them and suggest new phenomena not yet observed.

by lutusp 10y ago

mattkrause 10y ago

Let me give you an example, from visual perception. The "Feature Integration Theory" suggests that low-level image features are processed in parallel: you extract information about the color, orientation, and movement in parallel across the entire visual field. However, these representations are separate, and a second, serial process is needed to combine information across the two areas. This makes a specific, testable predictions. Suppose you're searching for a red triangle. If this shape is embedded in a sea of green triangles, your reaction time shouldn't vary as a function of the green triangles. The same thing should happen if the red triangle is surrounded by red circles--reaction times should be relatively constant regardless of the number of red circles. However, if you need to find a red triangle embedded in a mix of red circles and green triangles, you should a) be slower and b) your reaction time should be a function of the total number of shapes. I'd argue that this theory is empirical (run the experiment, record reaction times) and about as falsifiable as it gets (it's easy to test the difference in RT. vs. item # slopes). I'd also argue that this is a computational theory describing how visual search works, without worrying about the underlying implementation of that process. Clearly, it would be interesting to know that too, but it's certainly not necessary. David Marr proposed that cognitive processes could be studied on three levels: computational (what's the problem), algorithmic (what's a way to solve the problem), and implementation (what do the neurons do to run that algorithm), and each level was largely independent of the ones below.

lutusp 10y ago
You seem to be missing the point that, no matter how many hypotheses we make about the inner workings of the brain, we cannot turn them into science without either confirming or refuting them by direct examination of the brain itself. As long as we're hypothesizing about mechanisms that remain beyond direct observation, it's speculation. One cannot falsify a speculation. Psychology doesn't study the brain, it studies the mind. > I'd argue that this theory is empirical ... The observation is empirical but the theory isn't. It cannot become science without validation by way of empirical evidence. https://youtu.be/LIxvQMhttq4?t=32 https://youtu.be/LIxvQMhttq4?t=32 > I'd also argue that this is a computational theory describing how visual search works, without worrying about the underlying implementation of that process. Yes -- and because we cannot directly observe the processes we're hypothesizing about, we cannot make them a matter of empirical evidence, therefore we have no basis for falsification. https://www.britannica.com/topic/criterion-of-falsifiability https://www.britannica.com/topic/criterion-of-falsifiability Quote: "Criterion of falsifiability, in the philosophy of science, a standard of evaluation of putatively scientific theories, according to which a theory is genuinely scientific only if it is possible in principle to establish that it is false." > Clearly, it would be interesting to know that too, but it's certainly not necessary. Only necessary for science, otherwise not important.
- mattkrause 10y ago
  On the contrary, the point I'm trying to make is that you can study the processing done by whatever's in your skull (mind, brain, GPU, nanobots, whatever) while being totally agnostic about the underlying hardware. You can develop theories about this, test them, falsify them, and revise them. Returning to the feature integration theory, it says that during singleton search (red vs. green), reaction times should be constant regardless of the number of items, while reaction time should be a linear function of the number of items when the search involves combining information from multiple feature channels. You can test this with a junky laptop or even some drawings and a stopwatch. In fact, if you really want, I'll send you a script so you can test it yourself. You can falsify this: just fit lines to the (item count, RT) data and see if the slopes match the predictions. People have, in fact, done this, and have shown that this explanation of visual search isn't quite complete--weird things happen when the target is very rare, for example. Can you explain exactly what some neuroscience data would add here? Look, I'm not some hardcore dualist. I work in a systems neuroscience group and completely agree that brain-based theories are more interesting than phenomenological ones, which is why I put up with the hours, pay, etc. However, this doesn't make those psychological theories any less valid, nor does it make psychology less of a science. Anyway, there are lots of other processes that are not directly observable. Gravity, for example, wasn't directly observed until last year. Evolution can't be observed directly either.

Y_Y 10y ago

> The mind is not a physical thing I was with you until here. I'd say you were getting religious if you tried to represent the mind as anything other than an emergent physical phenomenon.

lutusp 10y ago
> I'd say you were getting religious if you tried to represent the mind as anything other than an emergent physical phenomenon. A similar argument could be made from the opposite perspective. The mind is not part of nature, of reality. It's an artificial philosophical construct, arising from observations of behavior, and on that basis extrapolating the existence of something for which there's no direct evidence. Not unlike God in that respect. By definition, an emergent physical phenomenon would be something that ultimately emerged in physical form. The mind cannot do that. I think you're speaking of behavior, which does meet the definition.
- mattkrause 10y ago
  I think you're putting a lot of weight on "study the mind" versus "study the brain." Not many psychologists are dualists. They tend to say "mind" because they want to abstract over the actual hardware--they're interested in studying what happens in the skull, not how it is implemented. This doesn't make it any less scientific than a biologist who studies where birds fly while neglecting the aerodynamics of the birds' wings.
  - lutusp 10y ago
    > They tend to say "mind" because they want to abstract over the actual hardware--they're interested in studying what happens in the skull, not how it is implemented. Yes, but asking what isn't science by itself, which tries to say how a particular observation came about. Also, psychologists don't really know what's happening inside our skulls. Studying the mind can't tell us what the brain is doing or how, any more than a computer display can tell us how a CPU works -- for the latter, we need access to the source, not its external manifestation. * If I say, “The night sky is filled with tiny points of light,” I've offered a description. Another observer might contradict my description, for example by emerging from his cave on an overcast night and not seeing any points of light, but the contradicting observation can itself be contradicted on the next clear night, without any chance for resolution. So, apart from being shallow, inconclusive and trivial, it's not science. * If I say, “Those points of light are distant thermonuclear furnaces like our sun,” I've offered an explanation, one that makes predictions about phenomena not yet observed and that's falsifiable by empirical test. On the basis of this explanation we might build a small-scale star (a fusion reactor) to see if our experiment shows any similarity to the spectra and behavior of stars. This deep explanation represents a theoretical claim that's linked to other areas of human knowledge, predicts phenomena not yet observed and is conclusively falsifiable by comparison with reality (our fusion reactor might fail to imitate the stars). It's science. > This doesn't make it any less scientific ... But it does -- one cannot falsify an observation, one can only contradict it. > This doesn't make it any less scientific than a biologist who studies where birds fly ... If the biologist only records where the birds flew, it's not science. If he crafts a testable, falsifiable theory about why the birds flew there, that might be science. Science is about crafting theories that go beyond simple observation, that explain them and suggest new phenomena not yet observed.