Knowledge as a Vritti Insights from Yoga Sutras and Cognitive Neuroscience

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Knowledge plays a crucial role in all of our lives. We are not just speaking of knowledge of specific subjects that we learn in school, but also of knowledge gained from life experience, pertaining to people, places and situations. From simple tasks like recognizing the face of a person we know, to making complex decisions in our professional and personal life, it is knowledge that underlies these processes.

What exactly is knowledge? In cognitive psychology, knowledge is defined as information about the world that is stored in memory; this information must be capable of being justified as true and be coherent. Interestingly, in the Yoga Sutras of Patanjali, verse 1.6 talks about pramana, valid means of knowledge, as one of the five categories of vrittis (modifications or fluctuations) of the mind-field, chitta. The subsequent verse (1.7) mentions the three modes of pramana, correct means of knowledge:

  1. Pratyaksha – direct perception through one’s senses
  2. Anumana – inference
  3. Agama – testimony of accomplished experts


Translation: Direct perception, inference and revealed authority are the three categories of the vritti called valid proof (pramana)

Before going into more detail about the three means of pramana, let us look at how knowledge is represented in the brain. Information that stands for an object, event or concept is physically represented as a network of neuronal connections in particular regions of the brain.  (A neuron is the fundamental unit of the brain and nervous system.)

Formats of knowledge representation in the brain

Research in the fields of psychology and neuroscience points to the fact that the brain uses multiple formats of representation of knowledge: images, feature detectors and statistical patterns in neural nets. Multiple formats are required because the act of cognition consists of numerous processes.

Let’s understand these representational formats with an example. Imagine that you are invited to a birthday party and you are perceiving the the table with the cake in front of you. When the eyes perceive the scene, the brain constructs a visual image of it in the occipital cortex, located at the back of the head. Images are modality-specific representations; that is, they stand for information received by a single sensory modality, namely vision. Similarly, information coming from the sensory modalities of audition, touch, taste and smell are represented as sense-specific memories. As the image develops, feature detecting neurons extract meaningful features from the image such as the shape and colour of the cake, the texture of the crumb, the frosting, the letters in edible ink and so on. The feature detection happens in certain regions of the occipital, temporal and parietal lobes. Finally, a network of conjunctive neurons in the temporal lobes link the neurons active in forming the image, along with the neurons active in the feature detection. These conjunctive neurons represent the statistical pattern that associate all the information together to represent the ‘birthday cake’ (Figure 1).

Figure 1: Formats of representation in the brain. Neurons active in forming the image of the cake (in occipital lobes) and feature detecting neurons (in occipital, temporal and parietal lobes) are linked together by conjunctive neurons in the temporal lobes to form a statistical pattern that represent the ‘birthday cake’. (Image courtesy: Smith and Kosslyn, Cognitive Psychology: Mind and Brain).

Statistical patterns: Knowledge representations as statistical patterns in neural nets are becoming increasingly interesting to researchers. The neural net is a format of representation in which an object, say the birthday cake, is represented as a statistical pattern such as 1100101000101. Biologically, the elements of a statistical pattern can be looked at as neurons (or populations of neurons) that are “ON” or “OFF, i.e., they fire or do not fire. When a neuron is said to “fire”, it means that it emits an electrical signal called action potential, which is important for communication between the neurons. The 1’s in the pattern indicate neurons that fire and the 0’s indicate neurons that do not fire.

These representations lay the groundwork for knowledge. Once the brain establishes memories that carry information about the world, all kinds of sophisticated cognitive abilities become possible. This particular insight from cognitive neuroscience shows the importance of stored representations in memory for higher cognitive abilities such as reasoning, deduction and deeper understanding. Perhaps this is the reason why the Indian education system emphasizes memorization and rote learning, as it forms the basis for understanding. This is a tangent to the main topic of this article, but worth mentioning nevertheless.


In the Vyasa Bhashya for Verse 1.7, it is explained that the mind-field is drawn towards and coloured by the objects of experience through the senses. The mind-field thus takes the form of a vritti (modification) whose content is the sensed object; this vritti is called pratyaksha, the means of knowledge through direct perception. It is said that pratyaksha “determines primarily the specific in a matter consisting of the general and specific”. In other words, during pratyaksha, it is the specific object that is perceived and not the general concept. For example, if one perceives a cat walking by, it is the specific cat, with a specific colour, size, fur density and so on perceived at that moment in time through the senses. It is not the general concept of cats that we have in our minds, that is, an image of an average cat that we have come across many a time.

It is further explained that during pratyaksha, the determinative process of the buddhi (intelligence) helps in identifying specific attributes that are unique to the object, distinguishing them from general or common attributes shared with other objects. For example, one might look at a butterfly and think of the general category of winged insects that includes butterflies and moths, but perceiving the brightly coloured wings and large size, one specifically determines it to be a butterfly.

Frontal lobes: Modern neuroimaging research shows that the brain’s frontal areas, which are widely associated with executive functions and intelligence, are active while categorizing objects using such specific attributes and definitions.

Vyasa’s commentary also states that it is Purusha, the pure consciousness principle, that is the cause of buddhi’s accurate apprehension. It is Purusha that gives a semblance of consciousness to the process of perception and the resultant vritti.


The Vyasa Bhashya describes anumana or inference as the vritti determining primarily the general; it is the invariant association between an object and its attribute or commonality between two objects that helps to produce a conclusion. The classic illustration given is the association between fire and smoke. Due to this association, when one sees smoke, one infers that there is fire.

It is clearly explained that anumana is the vritti that determines primarily the general. For example, you know that birthday parties are associated with cakes. If you see an unopened box on the table at a birthday party, you know that it is a cake even though you haven’t actually seen it. The cake that appears in the mind is a ‘general’ concept of cake and not the specific cake that is present in the box.

Category knowledge: Cognitive neuroscience refers to this process of association of objects with similar features as “categorization”. Objects with common attributes or properties can be grouped into categories. Category knowledge development in a two step process: first, representations of a individual members of a category are established; second, those representations are integrated.  For example, we have seen different types of cakes in our life. Each individual cake produces a unique statistical pattern of 0’s and 1’s. Although the statistical patterns are unique for each cake, they are similar because the actual cakes have common features. In the statistical patterns, certain conjunctive units are common to all representations (shown shaded in Figure 2a). This shared statistical pattern establishes the representation of the category, that is, the ‘general concept of cake’, not just a specific cake (Figure 2b). When someone mentions the word “cake”, the shared statistical pattern becomes active, even though a cake is not physically present, and produces a mental simulation of a cake that is roughly the average of previously experienced cakes (Figure 2c).

Figure 2. Representation of category knowledge (a) Each individual cake has a unique statistical pattern. There are some common units, reflecting the similarities of actual cakes. (b) The shared units of the statistical pattern establish the representation of the ‘general concept’ of cakes. (c) The word ‘cake’ activates the shared statistical pattern and produces a mental simulation of a cake that is roughly the average of previously perceived cakes. (Image courtesy: Smith and Kosslyn, Cognitive Psychology: Mind and Brain).

Categorization binds objects with similar features or attributes together into a general concept and therefore makes inference possible. Because category knowledge contains diverse information that goes much beyond what is immediately perceivable by the eyes and the senses, it enables one to draw useful inferences about things, people, and situations in life.


Finally, the third valid means of knowledge is described as agama: a matter directly perceived or inferred by an accomplished person and taught in the form of words to transfer his knowledge into the listener. The resulting vritti from that word, with its matter and meaning as its content, is the listener’s acquisition, agama. These words from Vyasa’s commentary lead to profound insights into the teaching-learning process that would require the writing space of an entire article. Let’s stop here for now!


Arya, Pandit Usharbudh. Yoga Sutras Of-Patanjali With The Exposition Of Vyasa. The Himalayan International Institute: Pennsylvania (1986).

Smith, Edward E., and Stephen M. Kosslyn. Cognitive psychology: Pearson new international edition: Mind and brain. Pearson Higher Ed, 2013.

Hills, Peter J and Pake, Micheal J. Cognitive psychology for dummies. John Wiley & Sons, 2016.