You Know What They Say About Assuming: The Likelihood Principle and Unconscious Inference

By Hannah Schultz

Have you ever taken a class in which on the first day, the professor immediately initiates actual learning? You take your seat, and all of a sudden there is a Power Point presentation on the projector and you’re supposed to be taking out your notebook. All the while, you’re wondering why there’s no entertaining ice breaker to let everyone introduce themselves. It is from this day forward, you know this is going to be a class that requires immense effort, and your professor even says, “There is a lot of material to go over, so I will start class at exactly 8 a.m. and end exactly at 9:30”.


We have all experienced our fair share of classes such as this, and if you haven’t yet in college, you will. However, proceed with caution because when it comes to studying for an exam, most students decide to wait until the last minute to cram as much information as possible. While going over the twelve chapters of content, you are more than likely skimming over the information and relating it to other subjects in order to remember. Due to Helmholtz’s likelihood principle, we should alter how we study.



Likelihood principle 



If we read over course material quickly, there is a great chance that we are not interpreting it correctly. The likelihood principle states, we perceive our world in the way that is most probable due to our past experiences. For example, if you see a diagram in your text book of two objects, how do you know that you are perceiving them correctly? You see picture A and with-out the prevalence of past experiences, you do not know if the pink rectangle is as shown in figure B versus as shown in figure C.

 However, due to the fact that you learn from your past experiences, you are able to deduce that the pink rectangle is most likely as shown in figure C 1.


Unconscious inference


            Along with the likelihood principle, according to Helmholtz, there is a process called the unconscious inference, in which our perceptions are concluded based off of unconscious assumptions. Go back to sitting in the desk in class, and having the thought about how it was going to be a rigorous course. That conclusion about the toughness of the class was based on an assumption of the professor’s attitude on the first day of class.

Compare to studying

Your question may be, how does this have anything to do with a difficult course, and before you doubt that I know actually nothing about the toughest class of your life, listen. In every-day life, we make assumptions about everything we perceive. When reading a text book or studying literature, our habit to skim over the material forces us to wrongly interpret information and relate it to events from our past, resulting in a misinterpretation. According to a study, Helmholtz defines the perceptual process as a problem solving technique that gathers cues and forms the most probable hypothesis based upon past understandings 2.

           Therefore, when studying instead of skimming, when you read the text book relate the concepts to previous knowledge. The key to this study habit is to ensure that the information being processed is also being originally interpreted correctly. Several studies have been conducted to investigate the relationship between the likelihood principle and language processing. The results have concluded that there is a strong parallel between the likelihood principle and language perception 3.


In another study, it is prevalent that the likelihood principle explains how we organize our perceptual information intake 4. It is important to utilize our organizational skills and stop making unconscious inferences about information not accurately interpreted.







In another study, it was concluded that what we learn directly influences what we perceive through the likelihood principle and unconscious inference 5. Unconscious inference navigates through perception based on past experiences. For example, if you experience an event and outcome A occurs after said event, every time after you experience that same event you will assume that outcome A will occur consecutively. Therefore, if you learn while reading your textbook that psychology is the scientific study of the human mind and its functions, and then you answer that correctly on an exam, you will always assume that to be true.



Now, when sitting in the impossible class, which you will inevitably encounter during your time in college, remember to read the literature thoroughly. As you are reading, apply the likelihood principle by relating the course content to a past experience, and it will organize perceptually, and make it easier to recall. Another note, do not assume that you understand the textbook just by skimming through the paragraphs and inferring that it relates to a past experience that is irrelevant. The likelihood principle and unconscious inference can cause stumbling blocks for new college students, but as soon as you realize how to navigate around the obstacle, you are able to apply these theories to study more efficiently.




  1. Van der Helm, P. A. (2000). Simplicity versus likelihood in visual perception: From surprisals to precisals. Psychological Bulletin, 126(5), 770-800.
  2. Pomerantz, J. R., & Kubovy, M. (1986). Theoretical approaches to perceptual organization. In K. R. Boff, L. Kaufman, & J. P. Thomas (Eds.), Handbook of perception and human performance (Vol. 2, pp. 36.1-36.46). New York: Wiley.
  3. Bod, R. (2002-01-01). Combining Simplicity and Likelihood in Language and Music. Proceedings of the Annual Meeting of the Cognitive Science Society, 24(24). Retrieved November 29, 2017.
  4. Chater, N. (1996). Reconciling simplicity and likelihood principles in perceptual organization. Psychological Review, 103(3), 566-581.
  5. Barlow, H. (1990). Conditions for versatile learning, Helmholtz’s unconscious inference, and the task of perception. Vision Research, 30(11), 1561-1571. Retrieved November 29, 2017.

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