Cognition is the acquisition of knowledge by the mechanical process of information flow in a system. In animal cognition, input is received by the sensory modalities and the output may occur as a motor or another response. The sensory information is internally transformed to a set of representations which is the basis for cognitive processing. This is in contrast to the traditional definition based on mental processes and originating from metaphysical philosophy.
Dictionaries commonly define cognition as a mental process for the acquiring of knowledge. However, this view originated from the assignment of mental processes to the act of thought. These mental processes originate from a metaphysical description of cognition that includes the concepts of consciousness and intentionality[1][2]. This also assumes that objects in nature are reflections of a true and determined form.
Instead, a material description of cognition is restricted to the physical processes available in nature. An example is from a study of primate face recognition where measurements of facial features serve as the basis for object recognition[3]. This perspective also excludes the concept that there is an innate and prior knowledge of objects, so instead cognition forms a representation of objects from their constituent parts[4][5], and the physical processes of cognition are not inherently and functionally deterministic.
Scientific work generally accedes to a mechanical description of information processing in the brain. However, a perspective based on the duality of physical and mental processing is retained in various academic disciplines. For example, there is a conjecture about the relationship between the human mind and a simulation of it[6]. This idea is based on assumptions about intentionality and the act of thought. Instead, a physical process of cognition is defined by the generation of action by neuronal cells without dependence on non-material processes[7].
Another result of physical limits on cognition is observable in the intention of moving a body limb, such as a person reaching for an object on a table. Instead, studies have replaced the assignment of intentionality with a material interpretation of this action, and show that the relevant neural activity occurs before the perceptual awareness of the motor action[8].
Across the natural sciences, the neural system is studied at various biological scales, including at the molecular level to the higher level of information processing and synthesis[9][10]. At this higher order perspective, the neural systems are functionally analogous to the deep learning models of computer science[11][12]. This allows for a comparative approach for understanding cognitive processes. However, at the lower scale, the artificial neural system is dependent on an abstract model of neurons and the network, so at this scale the animal neural system is not likely comparable.
The definition of cognition as used here is restricted to a set of mechanical processes. Also, the cognitive processing is described from a broad perspective with examples from the visual system and the deep learning approaches from computer science.
The visual cortical system occupies about one-half of the cerebral cortex. Along with language processing in humans, vision is a major source of sensory input and recognition of the outside world. The complexity of the sensory systems reveals an important aspect of the evolutionary process, as observed across cellular organisms, along with their countless forms and novelties. Evolution depends on physical processes, such as mutation and population exponentiality, along with a dependence on geological time scales for building biological complexity as observed at all scales of life. These effects have formed and shaped the biosphere of the Earth.
Life's vast complexity is seen by deconstruction of the camera eye. This novel form emerged over time from a simpler organ, such as an eye spot, and which depended on a sequence of adaptive changes[13][14]. These rare and unique events did not hinder an independent formation of a camera eye, as it occurs in the lineages of vertebrates and cephalopods. This is an example of evolution as a powerful generator of change in physical traits, although counterforces restrict the generation of an infinite number of varieties, including by the finiteness of the genetic code and the constraints of physical laws on traits, where these traits range at all biological scales.
The evolution of cognition and neural systems are expected to occur by a similar probabilistic process as theorized for the origin and design of the camera eye. Therefore, the neural systems are expected to show an efficiency in design, as in the other biological systems, especially since the neural system undergoes a coevolution and continual adaptation for operation with the sensory organs. However, this efficiency is also constrained by the limits of molecular and cellular processes.
“The biologically plausible proximate mechanism of cognition originates from the high dimensional information from the outside world. In the case of vision, the sensory data consist of reflected light rays that are absorbed across the two-dimensional surface, the retinal cells, of the eye. These light rays may range across the electromagnetic spectra, but the retinal cells are specific to a small subset of these light rays”[1].
Figure 1 shows the above view, in abstract form, as a sheet of neuronal cells that receive sensory input from the outside world. The input is processed by cell surface receptors and communicated downstream for processing by the neural system. The sensory neurons and their receptors can be imagined as a set of activation values that are undergoing change over time, and abstractly described as a dynamical system.
Figure 1. An abstract representation of information that is received by a sensory organ, such as the light rays absorbed by neuronal cells across the retinal surface of the camera eye.
The information processing at the sensory organs are tractable to study, but the downstream cognitive processes are less understood at a proximate level. The cognitive processes include the generalizing of knowledge, also referred to as transfer learning, and is a higher level of organization that is constructed from the sensory input[5][15][16]. Transfer learning is dependent on segmentation of the sensory world and identification of sensory objects with resistance to viewpoint, or perspective (Figure 2)[17]. In computer science, there is a model[4] designed for segmentation and robust recognition of objects. This approach includes the sampling of sensory input, the parts of sensory objects, and encoding the information in an abstract form for presentation to downstream neural processes. The encoding scheme is expected to include a set of discrete representational levels of unlabeled objects, and then employ a probabilistic approach for matching these representations to known objects in memory. Without the potential for a labeled memory that describes an object, then there is no opportunity for knowledge of the object, and a basis for knowledge in general.
Figure 2. The first panel is a drawing of the digit nine (9) while the next panel is the same digit as transformed by rotation.
Experts have investigated the question on whether there is an algorithm that explains brain computation[18]. They concluded that this is an unsolved problem, even though natural processes are inherently representable by a quantitative model. However, information flow in the brain is a product of a non-linear dynamical system, a complex phenomenon that is analogous to the physics of fluid flow, a complexity that may exceed the limits of computational work. Similarly, these systems are highly complex and not easily mirrored by simple mathematical descriptions[18][19]. They recommend an empirical approach for disentangling these kinds of systems.
An artificial neural system, such as the deep learning architecture, has a strong potential for testing the elements of of natural cognition. The reason is engineered systems are built from parts and relationships that are known, whereas in nature the origin and history of the system is obscured by time and a large number of events, and scientific knowledge require extensive experimentation that is often confounded with error from sources, both known and unknown.
It is possible to hypothesize about a model of object representation in the brain, and its artificial analog from deep learning. First, these cognitive systems are expected to encode objects by their parts, the basic elements of an object[3][4][5]. Second, it is expected that the process is stochastic as in other natural processes.
The neural network system is a programmable system[20], encoded with weight values along the connections in the network, and with activation values at the nodes. It is expected that the brain functions analogously at the level of information processing, since these systems are both based on non-linear dynamic principles in a network and of distributed representations of objects[5][18][21][22]. The encoding schemes are likely abstract and generated by probabilistic processes, and therefore it follows that the coding is not generated by a top-down deterministic process.
Moreover, a physical interpretation of cognition requires the matching of patterns for generalization of knowledge. This is consistent with a view of cognition as a statistical machine with a reliance on sampling for robust information processing. With advancement in deep learning methods, such as the invention of the transformer architecture[5][23], it is possible to sample and search for exceedingly complex patterns in a sequence of information, even including for object detection[24].
This sampling of the world is dependent on a sensory modality, such as vision or speech, and is complemented by a sampling of modalities which has the potential to lead to increased robustness in the steps of information processing and forming the internal representations.[25]
Microsoft Research released a deep learning method, based on the transformer architecture, along with formal inclusion of curated and structured data, to achieve parity with humans on common sense reasoning[26]. Their example of this kind of reasoning is described by a question on what people do while playing a guitar. The common sense answer is for people to sing. This association is not a naive one since the concept of singing is not a property of a guitar.
They designed the exams with questions and multiple choice answers. Their achievement of parity with humans is possible by including this curated and structured data, and concatenating it with the conventional data as processed from online and free-formed documents.
Their finding shows that an online corpus is not sufficient for the fully forming of concepts. The conventional transformer architecture is dependent and limited by the information inherent in a sequence of data for representation of conceptual knowledge. In their case, the missing component was the curated and structured data, and the results show a competitive capability for building concepts from representations as derived from the input data.
The use of a large sample of representations that correspond to an abstract or non-abstract object, or an event, is expected to increase robustness in the models of cognition[27]. Their knowledge of concepts is expected to form in the same manner. If there are missing parts of a concept, then a person would have difficulty in forming the whole concept and applying it during problem solving.
Is animal cognition as interpretable as a deep learning system? This question arises from the difficulty in disentangling the mechanisms of the animal neural system, whereas it is possible to record the changing states of an artificial system since its design is known. If the artificial system is analogous, then it is possible to gain insight into animal cognition[5][28]. However, an assumption for the analogy may not hold. For example, it is known that the mammalian brain is highly dynamic, such as in the rates of sensory input and the downstream activation of internal representations[18]. These dynamic properties were not feasibly modeled in current deep learning systems, a constraint of hardware design and efficiency[18]. This was an impediment to design of an artificial system that is approximate of animal cognition, although there are concepts for modeling these dynamics, such as an architecture that includes “fast weights” and provides a form of true recursion in the network[5][18]. Recently, there is interesting research for this architecture which overcomes the performance problem[29][30].
The artificial neural networks continue to scale in size and efficiency. This is accompanied by empirical approaches for exploring sources of error in these systems. This is dependent on a thorough understanding on the construction of these models. One avenue for increasing the robustness in the output is by combining many sources of sensory data, such as in the visual and language domains. Another approach is to establish unbiased measures for the reliability of model output[24]. Likewise, error in information processing is not resistant to bias in animals. In human cognition, there is a well documented bias in speech perception[31].
These approaches are integratable for emulating the modularity and breadth of function in an animal brain. For achieving this aim, meta-learning methods can create a formal, modular, and structured framework for combining disparate sources of data. This scalable approach would lead to building complex information systems and encompass the general processes of cognition[32].
Another area of importance is the property of generalization in a model of cognition. This goal is approachable by processing the levels of representation of sensory input, the process that presumably occurs in the ability of animals to generalize knowledge[4][33][34]. In an abstract context, this generalizability is based on the premise that information of the outside world is compressible, such as its repeatability in the patterns of sensory information, so that it is possible to classify objects and gain knowledge.
There is also the question of how to reuse knowledge outside the environment where it is learned, "being able to factorize knowledge into pieces which can easily be recombined in a sequence of computational steps, and being able to manipulate abstract variables, types, and instances"[5]. Therefore, it is relevant to have a model of cognition that includes the high level representations of the parts of a whole object, even for abstract objects. However, the dynamic and various states of the internal representations are also likely contributors to the processes of reasoning.
Lastly, there is uncertainty on the dependence of animal cognition on the outside world. This dependence has been characterized as the phenomenon of embodiment, so an animal cognition is also an embodied cognition, even in the case where the outside world is a machine simulation.[18][35][36] This is in essence a property of a robotic and mechanical system, where its functions are fully dependent on input and output from the world. Although a natural system receives input, produces output, and learns at a time scale constrained by the physical world, an artificial system is not as constrained, such as in reinforcement learning[36][37][38], a method that can reconstruct the sensorimotor function in animals.
Deepmind[36] developed artificial agents in a 3-dimensional space that learn in a continually changing world. The method employs a deep reinforcement learning method in conjunction with dynamic generation of environments that lead to the uniqueness of each world. Each of the worlds have artificial agents that learn to handle tasks and receive rewards for completion of objectives. An agent observes a pixel image of an environment along with receipt of a "text description of their goal"[36]. Task experience is sufficiently generalizable that the agents are capable of adapting to tasks that are not yet known from prior knowledge. This reflects an animal that is embodied in a world and is learning interactively by the performance of physical tasks. It is known that animals navigate and learn from the world around them, so the above approach is a thoughtful experiment in the virtual realm.
However, the above approach is fragile to tasks outside those of its learned distribution.
Abstract reasoning is often associated with a process of thought, but the elements of the process are ideally respresented by physical processes only. This restriction constrains the explanations for emergence of abstract reasoning, such as in the formation of new ideas. Moreover, a process of abstract reasoning may be compared against the more intuitive forms of cognition in vision and speech. Both these sensory forms occur by sensory input to the neural system. Without the sensory input, the layers of the neural systems are not expected to encode new information by some pathway, such as expected in the recognition of visual objects. Therefore, it is expected that any information system is dependent on an external input for learning, an essential process for knowledge.
It follows that abstract reasoning is formed from an input source received by the neural system. If there is no input that is relevant to a pathway of abstract reasoning, then the system is not expected to encode that pathway. This also leads to the hypothesis on whether abstract reasoning is comprised of one or many pathways, and the contribution of unrelated pathways, such as from visual cognition. It is probable that there is no sharp division between abstract reasoning and the other types of reasoning, and there is likely more than one form of abstract reasoning, such as for solving puzzles reliant on the manipulation of visual objects.
Another hypothesis is on whether these input sources derive mainly from internal representations. If true, then a model of abstract reasoning would involve the true forms of abstract objects, in contrast to the recognition of an object by reconstruction from sensory information input.
Since abstract reasoning is dependent on an input source, there is an expectation that deep learning methods, modeling the non-linear dynamics, are sufficient to model one or more pathways involved in abstract reasoning. This reasoning involves recognition of objects that are not necessarily sensory objects with definable properties and relationships. As with the training process to learn of sensory objects, it is expected that there is a training process to learn about the forms and properties of abstract objects. This class of problem is of interest since the universe of abstract objects is boundless and their properties and interrelationships are not constrained by the physical world.
A model of higher level cognition includes abstract reasoning[5]. This is a pathway or pathways that are expected to learn the higher level representation of sensory objects, such as from vision or speech, and that the input is processed and generative of a generalizable rule set. These may include a single rule or a sequence of rules. One model is for the deep learning system to learn the rule set, such as in the case of puzzles solvable by a logical operation[39]. This is likely the basis for a person to play a chess game, by memorizing prior patterns of information and events on the game board, and leading to generalization of the game system.
Similarly, another kind of visual puzzle is a Rubik's Cube. However, in this case it has a known final state where each face of the cube shares a unique color. Likewise, if there is a detectable rule set, then there must be patterns of information, including missing information, that allow construction of a generalized rule set.
The pathway to a solution can include the repeated testing of potential rule sets against an intermediate or final state of the puzzle. This iterative process is approachable by a heuristic search algorithm[5]. However, these puzzles are typically low-dimensional as compared to the abstract verbal problems, such as in inductive reasoning. The acquisition of rule sets for verbal reasoning require a search for patterns in a high-dimensional space. In either of these cases of pattern searching, whether complex or simple, they are dependent on the detection of patterns that represent sets of rules.
It is simpler to imagine a logical operation as the pattern that offers a solution, but it is expected that inductive reasoning involves high-dimensional representations than an operator that combines boolean values. It is also probable that these representations are dynamic, so that there is a possibility to sample many valid representations.
While the phenomenon of embodiment refers to an occupant of the 3-dimensional world, this is not necessarily a complete model for reasoning on abstract concepts. However, it is plausible that at least some abstract concepts are approachable in a virtual 3-dimensional world, and similarly, Deepmind[36] showed a solution to visual problems across a set of generated 3-dimensional worlds.
A population and distribution of tasks are also elements of Deepmind's approach. They show that learning a task distribution leads to knowledge for solving tasks outside the prior task distribution.[36][37]. This leads to potential for generalizability in solving tasks, along with the promise that increasing complexity in the worlds would lead to a further expansion in task knowledge.
However, the problem of abstract concepts extends beyond the conventional sensory representations as formed by cognition. Examples include visual puzzles with solutions that are abstract and require the association of patterns that extend beyond the visual realm, along with the symbolic representations from areas of mathematics[40].
Combining these two approaches, it is possible to construct a world that is not a reflection of the 3-dimensional space as inhabited by animals, but instead to construct a virtual world of abstract objects and the sets of tasks[37]. The visual and symbolic puzzles, such as in the case of chess and related boardgames[38], are solvable by deep learning approaches, but the machine reasoning was not generalized across a space of abstract environments and objects. The question is whether the abstract patterns to solve chess are also useful in solving other kinds of puzzles. It seems a valid hypothesis that there is at least overlap in the use of abstract reasoning between these visual puzzles and the synthesis of knowledge from other abstract objects and their interactions[36], such as in solving problems by the use of mathematical symbols and their operators. Since researchers are capable of abstract thought, it is plausible that generation of a distribution of general abstract tasks would lead to a working system for solving abstract problems in general.
If instead of a dynamic generation of 3-dimensional worlds and objects, there is a vast and dynamic generation of abstract puzzles, for example, then the deep reinforcement learning approach could train on solving these problems and acquire knowledge of these tasks[36]. The question is whether the distribution of these applicable tasks is generalizable to an unknown set of problems, those unrelated to the original task distribution, and the compressibility of the space of tasks.
Google Research showed that an unmodified reinforcement learning approach is not necessarily robust for acquiring knowledge of tasks outside the trained task distribution[37]. Therefore, they introduced an approach that incorporates a measurement for similarity among worlds that were generated by the reinforcement learning procedure. This similarity measure is estimated by behavioral similarity, corresponding to the salient features by which an agent finds success in any given world. Given these salient features are shared among the worlds, the agents have a path for generalizing knowledge for success in worlds outside their learned experience. Procedurally, the salient features are acquired by a contrastive learning procedure, and embeds these values of behavioral similarity in the neural network itself[41].
The above reinforcement learning approach is dependent on both a deep learning framework and an input data source. The source of input is typically a 2- or 3-dimensional environment where an agent learns to accomplish tasks within the confines of the worlds and rules[36][37]. One approach is to represent the salient features of tasks and the worlds in a neural network. As Google Research showed[37], the process required an additional step to extract the salient information for creating better models of the tasks and worlds. They found that this method is more robust to generalization of tasks. Similarly, in animal cognition, it is expected that the salient features to generalize a task are also stored in a neuronal network.
Therefore, a naive input of visual data from a 2-dimensional environment is not an efficient means for coding tasks that consistently generalizes across environments. To capture the high-dimensional information in a set of related tasks, Google Research extended the reinforcement learning approach to better capture the task distribution[37], and it may be possible to mimic this approach by similar methods. These task distributions provide structured data for representing the dynamics of tasks among worlds, and therefore generalize and encode the high-dimensional and dynamic features in a low-dimensional form.
It is difficult to imagine the relationship between two different environments. A game of checkers and that of chess appear as different game systems. Encoding the dynamics of each of these in a deep learning framework may show that they relate in an unintuitive abstract way[36]. This concept was expressed in the above article[37], that short paths in a larger pathway may provide salient and generalizable features. In the case of boardgames, the salient features may not correspond to a naive perception of visual relatedness. Likewise, our natural form of abstract reasoning shows that researchers capture patterns in these boardgames, and these patterns are not entirely recognized by a single ruleset at the level of our awareness, but instead are likely represented at a high-dimensional level in the neural network.
For emulation of a process of reasoning, extracting its salient features from a pixel image is a complex problem, and the pathway may involve many sources of error. Converting images to a low-dimensional form, particularly for the salient subtasks, allows for a greater expectation on generalization and repeatability in the patterns of objects and events. Where it is difficult to extract the salient features of a system, then it may be possible to translate and reduce the objects and events in the system to text based descriptions, a process that has been studied and introduced as a measure for interpretability in the procedure. The error in translation to text descriptions is also an observable phenomenon.
Lastly, since the advanced cognitive processes in animals involve a widespread use of dynamic representations, it is plausible that the tasks are not merely generalizable, but may originate in the varied sensory and memory systems. Therefore, the tasks would be expressed by different sensory forms, although the low dimensional representations are more generalizable, providing a better substrate for recognition of patterns, and essential for a general process of abstract reasoning.
In the 18th century, the philosopher Immanuel Kant suggested that synthesis of prior knowledge leads to new knowledge. This theory of knowledge extends the concept of objects from a set of perfect forms to a recombination of these forms, leading to a boundless number of representations. This was the missing idea for explaining the act of knowing, complexity of cognition, and nonnecessity of an immeasurable and cognitive ether. Therefore, the forces of knowledge are no longer dependent on description outside the realm of matter, or on hypotheses based on an unbounded complexity of material interactions.
It is possible to divide these objects and forms of knowledge into two categories, sensory and abstract. The sensory objects are ideally constructed from sensory input, even though this assumption is not universal. Instead, perception may refer to construction of these sensory objects, along with any error occurring in their associated pathways. In comparison, the abstract object is ideally a true form. An ideal example is a mathematical symbol, such as an operator for the addition of numbers. However, an abstract object may coincide with sensory objects, such as an animal and its taxonomic relationship to other forms of animals.
Therefore, one hypothesis is that the objects of knowledge are instead a single category, but that the input to form the object is from at least two sources, including sensation of the outside world and the representation of objects as stored in memory.
A hypothetical example is from the chess boardgame. A person is not able to calculate each game piece and position given all events on the board. Instead, the decision-making is largely dependent on boardgame patterns with respect to piece and position. However, the observable patterns as compared to all possible patterns is strongly bounded. One solution is the hypothesis that the patterns also exist as internal representations synthesized and formed into new patterns not yet observed. Evidence for this hypothesis is in the predictive coding of sensory input, that this compensatory action allows a person to perceive elements of a visual scene or speech a short time before its occurrence. This same predictive coding may apply to the internal representations, such as the chess gameboard patterns, and the ability to recombine prior knowledge. The process of creating new forms and patterns would allow a person to greatly expand upon the number of observable patterns.
In summary, the process of predictive coding of sensory information should also apply to the reformation of internal representations. This is a force of recombination that is expected to lead to a very large number of forms in memory, and for detection of objects and forms that were not yet observed. Knowledge by synthesis of priors has the potential to generate the magnitude of forms that is consistent with the extent of human thought. In this case, the cognitive ether of immeasurability or incomputability is not necessary for explaining the advanced forms of cognition.