Cognition: History
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Cognition is the acquisition of knowledge by the mechanical process of information flow in a system.

  • animal cognition
  • cognitive processes
  • physical processes

1. Introduction

1.1. The Many Definitions of Cognition

Common definitions of cognition often include the phrase mental process or acquisition of knowledge. Reference to mental processing descends from an assignment of non-material substances to the act of thinking. Philosophers, such as the Cartesians and Platonists, have written on this topic, including the relationship between mind and matter. This perspective further involves concepts such as consciousness and intentionality. However, these ideas are based on metaphysical explanations and not on a modern scientific interpretation [1].

The metaphysical approach is exemplified by the philosopher Plato and his Theory of Forms, a hypothesis of how knowledge is acquired. The idea is that a person is aware of an object, such as a kitchen table, by comparison with an internal representation of that object’s true form. The modern equivalent of this hypothesis is that our recognition of an object is by the similarity of its measurable properties with its true form. According to this theory, these true and perfect forms originate in the non-material world.

However, face recognition in primates shows that an object’s measured attributes are not compared against a true form, but instead that recognition is from a comparison between stored memory and a set of linear metrics of the object [2]. These findings agree with studies of artificial neural networks, an analog of cerebral brain structure, where objects are recognized as belonging to a category without prior knowledge of the true categories [3].

The theory of true forms originates from a thinking of a perfectly designed world with deterministic processes, while a theory absent of true forms may instead depend on probabilistic processes. The rise of probabilistic thinking in natural science has coincided with modern statistical methods and explanations of natural phenomena at the atomic level [4].

A modern experimental biologist would approach a study of the mind from a material perspective, such as by the study of the cells and tissue of brain matter. This approach is dependent on reduction of the complexity of a problem. An example is from economics, where an individual is generalized as a single type and consequently the broader theories of population behavior are based on this assumption [5]. There is a similar approach in Newtonian physics where an object’s spatial extent is simplified as a single point in space.

Since some natural phenomena are not tractable to mechanistic study, concepts exist that are not solely based on material and physical causes. However, it is necessary to base science theory of brain function on natural mechanisms while disallowing mental causation. There are exceptions where the physical world is visually indescribable and solely dependent on mathematical description, but these occurrences are typically not applicable to the investigation of life at the cellular level.

1.2. Mechanical Perspective of Cognition

Even though a mechanical perspective of neural systems is not controversial, there remains a non-mechanical and metaphysical perspective concerning our sensory perception of the world. An example is the philosophical conjecture about the relationship between the human mind and any simulation of it [6]. This conjecture is based on assumptions about intentionality and the act of thinking. However, others have presented scientific evidence where these assumptions do not hold true [7]. One example is the mechanism for an intent to move a body limb, such as in the act of walking. Whereas the traditional perspective expects a mental process of thinking that leads to the generation of these body movements, instead the mechanistic perspective is that a neuronal cell is the generator of the intent of a body movement [8].

While a metaphysical explanation for phenomena is applicable to some areas of knowledge, such as in the study of ethics, these explanations are not informative of nature where the physical processes are expected. In the case of neural systems, the neurons, their connections, and the neural processes are measurable by their properties, so their phenomena are assignable to material causes instead of mental causes. Further, there is a hierarchy of cellular organization that describes the brain where each level of this hierarchy is associated with a particular scientific approach [9]. An example is at the cellular level where the neurons are studied by the methods of cellular anatomy. This area of study also includes the mechanisms for neuron formation and communication between neurons.

Neural systems may be studied at a higher-level perspective, such as at the level of brain tissue or how information is communicated throughout the neural system [10]. The information processing of the brain is particularly relevant since it has a close analog with the artificial neural network architectures of computer science [11,12]. However, the lower levels of biological organization are not as comparable, such as where an artificial neural system is firmly based on an abstract and simplified concept of a neuronal cell and its synaptic functions.

2. Mechanisms of Visual Cognition

2.1. Stochastic Processes in Biology

Vision is the better studied of the sensory systems in primates [13,14]. It is particularly relevant since the visual processes occupy one-half of the cerebral cortex [15]. There is theory from the cognitive sciences that both vision and language are the major drivers for acquiring knowledge and perception of the world. It may seem daunting to imagine that our vivid awareness of a scene is built upon levels of basic physical processes. However, cellular life has generated a high degree of complexity by layering physical processes, such as mutation and population exponentiality, over an evolutionary time scale.

This problem of causation of complex phenomena has occurred in explanations for the origin of the camera eye. The formation of a camera eye that has transformed from a simpler organ, such as an eye spot, requires a model with a very large number of advantageous modifications over time [16,17]. A casual observer of the different forms of eyes, such as for this case, would find it difficult to imagine a material process that could design a functional camera eye from a simpler form. The experienced observer would instead invoke biological processes, such as random morphological change [17] and selection for those changes that favor an increase in the rate of offspring production. The result is the potential for a complex adaptation.

Further evidence that the formation of a camera eye is within the reach of natural processes is provided by the analogous camera eye in a lineage of invertebrate cephalopods. This resulted from an adaptation that occurred independent of the origin of the vertebrate camera eye. Yet, another case of Darwinian evolution is in the optimized refractive index of the camera eye lens. This adaptation occurred by modifications that led to recruitment of protein molecules from other uses to the lens of the eye [18].

There is another case of independent evolution as observed in the neural circuity of animals. The circuit for motion detection in the visual field has converged on a similar design in two different eye forms, both the invertebrate compound eye and the mammalian camera eye [19]. These examples show evolutionary convergence on a similar physical design and evolution’s potential for forming complex biological systems. In addition, the process of evolutionary convergence is dependent on developmental constraint on the kinds of modifications, otherwise the chance of convergence on a single design is expectedly low.

These are all examples of natural engineering of life forms by stochastic processes. They are not deterministic processes since they are not directed toward a final goal, but instead the adaptations are continually undergoing change by genetic and phenotypic causes.

The neural system of the brain is a direct analog of the above processes. The organ is considered highly complex and our perceptions are not easily translated to cellular level mechanisms. However, by the same probabilistic processes, the neurons and their interconnections have evolved into a cognitive system that is capable of complex computation with large amounts of sensory data. These cognitive processes include the identification of visual objects, encoding of sensory data to an efficient format, and pattern matching of visual objects to memory.

2.2. Abstract Encoding of Sensory Input

The biologically plausible proximate mechanism of cognition originates from the receipt of high dimensional information from the outside world. In the case of vision, the sensory data consist of reflected light rays that are absorbed across a two-dimensional surface, the retinal cells of the eye. These light rays range across the electromagnetic spectra, but the retinal cells are specific to a small subset of all possible light rays.

From an abstract perspective, the surface that receives the visual input is a two-dimensional sheet of cells where each cell has an activation value at a point in time (Figure 1). Over a length of time, the distribution of these activations is undergoing change, so the neural system is reporting from a dynamic state of activations. This view at the visual surface is representative of both the spatial and temporal components of the proximate cause of vision.

Figure 1. An abstract representation of data that are received by a sensory organ, such as light rays that are absorbed by cells along the surface of the retina of a camera eye. The drawing shows the spatial pattern, but there is also a temporal dimension since this sensory input data are changing over time.

This representation of sensory data is similar to that received by artificial neural network systems. These artificial systems are capable of identifying objects in a visual scene and labeling them by their membership to a category of related objects. This also shows analogous function between the artificial process and natural cognition [20].

The open problem has been generalizing this knowledge (transfer learning) that is acquired from processing sensory input data. This is the essential problem for artificial systems in emulating cognition in animals. However, there is recent work that employs artificial models of transfer learning [21,22].

A related problem is in identifying an object where the viewpoint is variable. It is addressed by a model [3] that is designed for biological realism, along with a robust architecture for sampling the parts of an object. This approach includes the sampling of visual data which are then encoded in an abstract format, a vector of number values. Specifically, this sampling occurs across blocks of columns in a visual scene. Further, each column consists of a set of vectors where each vector is assigned to a discrete category by its level of representation of the input data (Figure 2). These processed data are then utilized for finding columns of similarity that correspond to the parts of an object, a consensus-based approach toward establishing a robust identification of an object.

Figure 2. A model for processing of visual objects. The first panel shows a visual scene. The next panel shows an open circle which represents a region with a potential object. The third panel is an enlargement of this region. The final panel contains three open diagonal shapes that are abstract representations of the information in the image. They are ordered from bottom to top by low to high level of abstraction.

Previous approaches to artificial systems have often overfit the network model to a training data set. Overfitting hinders the generalizability of the final model [23]—in this case, the model is a network of nodes interconnected with weight values. The overfitting problem leads to loss of transferability of the model to other applications. Nature solves this problem by a set of processes. One is the visual processing for spatial and temporal invariance of an object in a scene [24,25]. This leads to a more generalized form of the object than otherwise.

A second and complementary method is to neurally code the object by metrics that are abstract and generalizable. This reflects the example where a photograph of a cat is encoded so that it matches to both another photograph and a pencil sketch of the cat. This generalizability in identifying objects is now possible in the case of artificial systems [26]. Additionally, this generalizability leads to corrections for the variability in an object’s form, such as change in its orientation, deobfuscation against the background, or detection based on a partial view (Figure 3).

Figure 3. (a) The first panel shows a photograph of a visual scene that contains a table along with other objects. The second panel in (a) is the same scene but transformed so that it appears as a pencil sketch drawing; (b) The first panel is a visual drawing of the digit nine (9), while the next panel is the same digit but transformed by rotation of the image.

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