In biological psychology, there is one of my favourite topics in psychology. It might not be related to clinical psychology, mental health or even forensic psychology, but I love it anyway. Psychophysics is a fascinating area of psychology that has always grabbed my attention and made me want to understand more about how a physical stimulus leads to a psychological experience. For example, how does physical stimuli of chocolate create a chocolate taste in our minds, and how does chocolate create the psychological experience of pleasure. These are some of the questions that psychophysics aims to answer. In this biological psychology podcast episode, you'll learn what is psychophysics, what does psychophysics cover and what might the future of psychophysics be. If you enjoy learning about physiological psychology, biopsychology and how our physical environment impacts our psychological processes then this will be a brilliant episode for you.
Today’s psychology podcast episode has been sponsored by Biological Psychology. Available from all major eBook retailers and you can order the paperback and hardback copies from Amazon, your local bookstore and local library, if you request it. Also available as an AI-narrated audiobook from selected audiobook platforms and library systems. For example, Kobo, Spotify, Barnes and Noble, Google Play, Overdrive, Baker and Taylor and Bibliotheca.
What Is Psychophysics?
Personally, I flat out loved learning for a single lecture about human perception because of a single area of psychology that focuses on the interception between our physical environment and our psychological experiences. That is what the area of psychophysics aims to study and expand our understanding of human perception. For example, right now at the time of writing, I’m listening to some “coffee shop jazz” livestream on YouTube (this is the physical environment) and it is helping me to concentrate, feel relaxed and feel content. Why do I feel like this because I have physical music playing in the background?
Equally, why did I feel happy (a psychological experience) when I listen to I Will Survive or Carol Of The Bells? Or when I watch Heartstopper on Netflix?
Why do these physical experiences cause me to have a psychological sensation or feeling?
This is why psychophysics is so important to understand why the physical world impacts us.
Overall, psychophysics is the empirical study of how the physical world and our psychological experiences intertwine. This allows us to expand our knowledge about human perception.
What Do Psychophysicists Research?
Like most areas of psychology, there is an infinite number of topics to study even within a subfield of psychology. For example, I conduct mental health research, but within mental health, you can study treatment modules, treatment effectiveness, depression, anxiety, eating disorders, sexual disorders, biased cognitive processes and on and on and on.
Psychophysics has a lot of different avenues for researchers to explore as well. For instance, one researcher might want to study how a “just noticeable” (probably the only concept in this topic I remember from second-year undergrad) change in light levels impacts someone’s perception of a stranger. Then again, another researcher might want to investigate how a change in the sugar content of a cake changes the level of happiness we experience if we eat it before an exam. Lastly, a researcher could investigate how temperature impacts and warps our perception of time and how much fun we’re having.
There are so many different areas that you can research within psychophysics.
Ultimately, psychophysics is all about the fascinating relationship between our sensory experiences and our physical stimuli. In other words, psychophysics aims to decode how our brain makes sense of the world and create psychological experiences for us. Just like why
listening to “coffee shop jazz” helps me feel relaxed and focused.
What Is Threshold Theory and Signal Detection Theory?
When you learn about psychophysics at undergrad level, you get introduced to Threshold Theory as this is a major theory that aims to explain how physical stimuli impact our perceptions. The theory investigates how the minimum amount of a stimulus is needed for a person to detect a psychological sensation. For example, how much sugar is needed in a chocolate bar for it to taste sweet to a person. As you can imagine this changes for everyone so let’s say that 5g of sugar is needed for Isabella to say a chocolate bar is sweet whereas Barbara might only need 1 gram of sugar.
This leads us to another theory.
Signal Detection Theory builds upon Threshold Theory by adding a decision-making element in perception, because this theory proposes that perception isn’t only about the strength of a stimulus. Instead, it is about the strength as well as our ability to detect the stimulus. I’m actually a good example of this because my spicy tastebuds are nowhere near as sensitive as the rest of my family’s so they can be dying after eating a spicy dish but I will be fine and act like it’s nothing. Therefore, not only is my Threshold of spicy higher, it could be argued that my ability to even detect spicy is lower than theirs.
Moreover, Signal Detection Theory has a lot of interesting real-world applications that go beyond the scope of this podcast episode. Such as, this theory can explain how radiologists can spot tumours in X-rays and why people sometimes think they’ve heard their phone buzz when it actually hasn’t.
What Are Weber’s Law, Fechner’s Law and Steven’s Power Law?
Considering I live with two physics students who are constantly talking about different laws of physics, I feel this is definitive proof that psychology has mixed perfectly with physics to produce this intersecting discipline.
Therefore, Weber’s Law proposes that the just-noticeable difference between two stimuli is proportional to the magnitude of the stimuli. In other words, if you have 2 chocolate bars, one with 1 gram and another with 2 grams of sugar. Then another 2 chocolate bars altogether, one with 10 grams and another with 11 grams. It is easier to tell the first two apart because of the first two have greater magnitude.
Building upon this, Fechner’s Law proposes that the perceived intensity of the stimulus is proportional to the logarithm of its physical intensity. For instance, the hotter the physical stimulus of a chilli, the greater the psychological sensation of spiciness.
Finally, Steven’s Power Law proposes that in reality, the relationship between the physical magnitude of a stimulus and the perceived intensity of the psychological experience can be described as a power function. This Law has been applied to sensory modalities, like the perceived loudness of sounds as well as brightness perception.
On the whole, when it comes to these theories and Laws, these are the key concepts that help to form the foundation of psychophysics and our expanded understanding of how physical stimuli create psychological experiences.
Why Does Psychophysics Matter? Using Psychophysics In The Real World
Sometimes I think a major problem that all sciences have, including psychology, is that after looking at the theory behind a concept, we end up getting confused about why this is useful to know. As well as I often question how is this psychological concept useful in the real world as I am a firm believer that the entire point of science is to help improve lives and make the world a better place.
When it comes to psychophysics, this has real world implications because it helps us to understand our senses like hearing, taste, smell, sight and our feelings. Also, it helps us to understand how our senses adapt in response to the environment. For instance, habituation is the process of us not noticing a physical stimulus after a while once we know it doesn’t pose a danger to us. Like we notice when a fan starts up but after a while we stop noticing the fan’s noise.
Moreover, psychophysics really helps decision-making and cognitive psychology research as psychophysics deepens our understanding of how we perceive and process information. As well as it shows us how our complex cognitive processes work. For instance, psychophysics research on how our brains process temporal information is useful for understanding multitasking and eyewitness testimony.
Lastly, if we look at clinical psychology, psychophysics allows us to better understand, assess and treat sensory disorders. Such as, we can now create more accurate hearing tests and create therapies for conditions like synaesthesia, where all our senses blend together. This is only possible because of psychophysics.
There are more applications but you get the gist. Psychophysics is very useful to our understanding of human behaviour.
What is The Future of Psychophysics Research?
In case you’re interested in psychophysics research and you might want to conduct your own in the future, you want to be aware of the trends. For instance, psychophysics research is starting to use a lot more neuroscience and brain imaging technology so researchers want to combine the traditional psychophysics methods with the cutting-edge techniques that neuroscience provides us. These include using fMRIs and EEG techniques to study the intersection of our physical environment and psychological experiences. Especially, these cutting-edge techniques allow us to see what’s happening in the brain as we feel these experiences.
I still maintain I would flat out love to be a part of a fMRI study, because it sounds fascinating.
Additionally, with the rise of virtual and augmented reality, psychophysics researchers are wanting to incorporate this new technology into their studies. You could create a virtual environment and stimulate or manipulate it to induce certain phenomena and make predictions about human behaviour. For example, if you wanted to understand the psychological sensation of overwhelm then you might want to create a virtual environment of a mosh pit at a concert and put someone in there. I hate the idea of mosh pits because of my autism and they sound like hell on earth.
Anyway, that is a potential idea for future research. Ultimately, virtual reality allows you to control every single aspect of someone’s sensory input.
Finally, computational modelling could be a future trend in psychophysics research because if you create a large computational model of people’s perceptual processes then you can refine and test theories in ways that weren’t previously possible for researchers.
Cognitive Psychology Conclusion
Even though I always tell people I flat out love psychophysics as a topic, it has been years since I’ve looked into and I am very glad I’ve returned to the topic. Sure, I had forgotten how many theories and laws are involved, but it is fascinating to understand how physical sensations create psychological sensations in the brain. That is amazing to me.
Therefore, as we spoke about Threshold Theory, Signal Detection Theory, Webbs, Stevens and Fechner’s Laws, I want you to know that this might be a complex area. Yet in psychology and when it comes to your interest in this great profession, never let complexity stop you. If you’ve enjoyed today’s episode then keep exploring, keep learning and keep developing your interest in psychophysics or any other area of psychology.
All you truly need to be successful in science is passion for a topic. It is that passion that will drive your learning, your improvement and you wanting to do the best you possibly can.
I am not interested enough in psychophysics to want to study it for my career, but keeps me interested in psychology along with hundreds of other tiny topics. And that is why I love psychology, I love this podcast and I love my life.
Passion really is the key to success.
I really hope you enjoyed today’s forensic psychology podcast episode.
If you want to learn more, please check out:
Biological Psychology. Available from all major eBook retailers and you can order the paperback and hardback copies from Amazon, your local bookstore and local library, if you request it. Also available as an AI-narrated audiobook from selected audiobook platforms and library systems. For example, Kobo, Spotify, Barnes and Noble, Google Play, Overdrive, Baker and Taylor and Bibliotheca.
Have a great day.
Biological Psychology References and Further Reading
Bass, C. DeCusatis, J. Enoch, V. Lakshminarayanan, G. Li, C. MacDonald, V. Mahajan, & E. Van Stryland (Eds.), Handbook of Optics, Volume III: Vision and Vision Optics (3rd ed., pp. 3.1-3.12). New York: McGraw-Hill.
Ehrenstein, W. H., & Ehrenstein, A. (1999). Psychophysical methods. In U. Windhorst & H. Johansson (Eds.), Modern Techniques in Neuroscience Research (pp. 1211-1241). Berlin: Springer.
Fechner, G. T. (1860). Elemente der Psychophysik. Leipzig: Breitkopf und Härtel.
Gescheider, G. A. (2013). Psychophysics: the fundamentals. Psychology Press.
Green, D. M., & Swets, J. A. (1966). Signal detection theory and psychophysics. New York: Wiley.
Kingdom, F. A. A., & Prins, N. (2016). Psychophysics: A practical introduction (2nd ed.). London:
Academic Press.
Knoblauch, K., & Maloney, L. T. (2012). Modeling Psychophysical Data in R. New York: Springer.
Leonov, Y. P. (1975). Decision theory and the concept of threshold in psychophysics. Soviet Psychology, 13(3), 78-90.
Lu, Z. L., & Dosher, B. (2013). Visual psychophysics: From laboratory to theory. MIT Press.
Pelli, D. G., & Farell, B. (2010). Psychophysical methods. In M.
Prins, N. (2016). Psychophysics: a practical introduction. Academic Press.
Stevens, S. S. (1957). On the psychophysical law. Psychological Review, 64(3), 153-181.
Stevens, S. S. (1960). The psychophysics of sensory function. American scientist, 48(2), 226-253.
Wichmann, F. A., & Jäkel, F. (2018). Methods in psychophysics. In J. T. Wixted (Ed.), Stevens’ Handbook of Experimental Psychology and Cognitive Neuroscience (pp. 1-42). Hoboken, NJ: John Wiley & Sons.
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