3.8 The Visual System and Environmental Information Exchange

In the fi rst chapter, it was made clear that organisms exchange information

with environments, that these environments can comprise interactions

within the organism as well as interactions with the external world

of the organism, and that environmental pressures can be described in

terms of information that is exchanged within the organism and/or

between environment and organism. Such exchanges with environments

also affect the visual system. This is the last section of this chapter, and

it acts as an important segue into the next chapter where I deal with

the evolution of the visual system. This is so for two reasons: it is the

internal environment of the cell related to genetic mutations in cell differentiation

where evolution principally takes place, and, it is the external

environment of the organism as a whole that acts as the condition for

the possibility of the evolution of the visual system and scenario visualization.

In this section, I describe fi rst how the internal environment of the organism’s processes and subsystems has an effect upon the visual

system. Then, I describe the effects of the external environment upon

the visual system.

The following examples all illustrate that the workings and interactions

of the brain act as internal environmental pressures that affect the processes

and functioning of the visual system. First of all, with the discovery

of HOX genes it has been shown that much of an organism’s phenotypic

characteristics are under direct genetic control. For example, moving

around, replacing, or taking out certain Drosophila (fruit fl y) HOX genetic

sequences produces mutated and monstrous results—antennae grow out

of abdomens, appendages grow out of heads, or basic parts are missing

(Nüsslein-Volhard & Wieschaus, 1980). The visual system is no exception

to this rule, as researchers have been able to adjust gene sequences related

to the visual systems of Drosophila, fi sh, amphibians, mice, and hedgehogs

(Chitnis, 1999; Maconochioe, Nonchev, Morrison, & Krumlauf, 1996;

Belloni et al., 1996; Goddard et al., 1996).

The important point to realize is that the experimenter’s adjustments to

the genetic code are directly analogous to the natural mutations that occur

on a regular basis in the reproductive lives of organisms. During cell division

and reproduction, genes go about their functioning in their own

chemical environments of the cell. What takes place in those environments

directly affects genetic formation in terms of mutant alleles (alternate

forms of a particular gene). When neurons differentiate, there are

natural genetic mutations that constantly occur because of chemical infl uences

upon chromosomal chains. In fact, if it were not for the regular

occurrence of mutant alleles, every living thing would look exactly like everything

else (Mayr, 1976; Eldredge, 2001). The processes associated with

mutant allele formation—rife with internal environmental pressures—

account for the phenotypic diversity of living things. In the next chapter,

before tracing the evolution of the brain and visual system, I talk more

about genetic mutations in relation to the environments of organisms.

Another example illustrating the effect of internal environmental pressures

upon the visual system has to do with neurulation, the successful

positioning of the various kinds of neurons in their appropriate spots

throughout certain developmental stages. Formation of the neural tube,

some three weeks after conception in humans, depends on a fairly precise

sequence of changes in the shape of individual cells, as well as the connections

of cells to one another. Timing is a factor in the process, since

neurulation must be coordinated with the ectoderm (outer layer of cells)

and mesoderm (middle layer of cells) of the neural tube. At the molecular level, neurulation is dependent upon specifi c sequences of gene expression

that are affected, to a large degree, by the positions and local chemical

environment of the cell. For example, a defi ciency of folate—a chemical

found to be important in the healthy development of the neural tube—

may cause a malformation of the retina, which develops out of the ectoderm.

This is one reason why doctors will ask women to take certain doses

of folate during pregnancy.

A fi nal example that illustrates the effect of internal environmental pressures

upon the visual system has to do with the neurotrophic theory, that is,

the idea that neurons compete for space in their own environment of the

brain (Reichardt & Fariñas, 1997). It is well-known that the developing

nervous system overproduces connections in great excess during development.

Through programmed cell death, as well as through a competition

for space, neuronal connections are pruned away as the nervous system

continues to develop. Hubel & Wiesel (1962, 1968) coined the term binocular

rivalry, which has to do with the inputs from both eyes in layer IV

competing for space (Myerson, Miezin, & Allman, 1981; Lumer, 2000).

Interestingly enough, this internal environmental confl ict is necessary for

the appropriate development and functioning of the nervous system (Craig

& Lichtman, 2001; cf. Lumer, Friston, & Rees, 1998; Zhang, Tao, Holt,

Harris, & Poo, 1998). Other forms of visual competition have been documented

(e.g., Antonini & Stryker, 1993; Blake & Logothetis, 2002; DiLollo

et al., 2000). Also cats, rats, and birds that have had their eyes occluded or

removed in early development show evidence of synaptic competition for

the unused visual space (Shatz & Stryker, 1978; Antononi & Stryker, 1993).

It is important to note that overproduction and competition were the fi rst

two observations Darwin (1859) made concerning species in general that

led to his formation of evolutionary theory.

There is a time frame in the development of the nervous system known

as a critical period. During this critical period, it is important for the nervous

system to receive information from the external world so as to aid in

appropriate neuronal maturation and synapse formation. As Zigmond

et al. (1999, p. 637) make clear: “During a critical period, the pathway

awaits specifi c instructional information, encoded by impulse activity, to

continue developing normally. This information causes the pathway to

commit irreversibly to one of a number of possible patterns of connectivity.

If appropriate experience is not gained during the critical period, the

pathway never attains the ability to process information in a normal

fashion and, as a result, perception or behavior is permanently impaired.”

It is widely agreed that a combination of natural genetic factors (nature) as well as environmental stimuli (nurture) are necessary for normal, healthy

nervous system development. Notably, even though it is the genetic blueprint

that acts as the formal guideline by which differentiated neurons

move into position in development, there can be material factors in the

environment of the neuron—like some kind of lesion or another mutated

neuron—that prevent the neuron from achieving its blueprinted designation.

It is not only the environment of the neuron but also the external

environment of the organism that affect the development of the nervous

system. For example, Bear et al. (2001) note that a lack of appropriate

nutrition, socializing, and sensory stimulation can contribute to the malformation

of dendritic spines, a key factor in mental handicaps.

The sensory pathways from one brain region to the next are organized

in such a way that neighboring groups of neurons maintain the spatial

relationship of sensory receptors in the periphery of the body. In fact, the

olfactory, visual, and somatosensory systems share the common feature of

topographic mappings of sensory surfaces, as well as parallel processing,

cortical modules, multiple cortical representations, and synaptic relays in

the dorsal thalamus. Topographical organization is an important way of

conveying information about the world to the nervous system. In essence,

the sensory pathways in the brain topographically refl ect the spatial relationships

of the environment (Kandel et al., 2000; Kosslyn, Thompson,

Kim, & Alpert, 1995). What this suggests is that the environment determines,

to a great extent, what we cognize. This has caused Sekuler & Blake (2002, p.

26) to claim that the “information picked up by the senses is not merely

a series of unrelated, incoherent data. Instead, sensory information closely

conforms to predictable, structured patterns. These patterns arise from the

very nature of the physical world itself, the world our senses have evolved

in.” Sekuler & Blake (2002, p. 168) also claim: “Organization in perception

mirrors the organization of real objects as they actually exist. The correspondence

between perceptual experience and the objects represented in

that experience is not accidental. After all, the visual system did evolve for

a purpose, namely to inform one about the objects with which one needs

to interact.”

The Gestalt psychologists noted that the visual system has built-in

mechanisms whereby the visual scene is grouped according to the following

principles: closure, the tendency of the visual system to ignore

small breaks or gaps in objects; good continuation, the tendency to group

straight or smoothly curving lines together; similarity, the tendency

to group objects of similar texture and shape together; and proximity,

the tendency to group objects that are near to one another together. Numerous studies have ratifi ed these principles as refl ective of the visual

system (Wertheimer, 1912, 1923; Brunswik & Kamiya, 1953; Kanizsa,

1976, 1979; Peterhans & von der Heydt, 1991; Gray, 1999; Sekuler &

Blake, 2002). These mechanisms can work only if the environment actually

displays the features on which the visual system is capitalizing.

There must be these kinds of regularities out there in the world, or else

it seems these principles would not be able to be delineated. Over 100

years ago, James (1890, p. 4) noted that mind and world “have evolved

together, and in consequence are something of a mutual fi t,” and the

Gestalt principles underscore this mutual fi t. Further, in reference to the

second chapter, where I dealt with metaphysical and epistemological

forms of emergence, this apparent mutual fi t of mind and world underscores

the argument from miracles. One might argue that it would certainly

be miraculous for the Gestalt psychologists to delineate their

principles if there were not this mutual fi t between mind and some

actually existing environment in which the mind fi nds itself.

It also has been shown that neuronal size and complexity—as well

as numbers of glial cells—increase in the cerebral cortices of animals

exposed to so-called enriched environments, that is, environments where

there are large cages and a variety of different objects that arouse curiosity

and stimulate exploratory activity (Diamond, 1988; Diamond &

Hopson, 1989; Mattson, Sorensen, Zimmer, & Johansson, 1997; Receveur

& Vossen, 1998). In these environments, it is important that animals

be exposed to objects having a wide variety of shapes, colors, and sizes

because there seems to be a close correlation between seeing these kinds

of objects and brain development. From such data, we can infer that

experiences in environments are refl ected to some degree in the structure

of our brains.

Add to this the most recent data suggesting that regions of the brain can

be trained, through mental and physical exercises, to pick up tasks from

other regions. The evidence for this comes from stroke patients who regain

the ability to speak, musicians who relearn how to play an instrument

after nerve damage, and cerebral palsy patients who learn to perform

activities long thought impossible to perform (Holloway, 2003; van Praag,

Kempermann, & Gage, 2000; Schwartz & Begley, 2002). Not only does this

suggest that certain brain processes are highly malleable and fl exible

(Malenka & Siegelbaum, 2001; Singer, 1995) but it again points to the fact

that the external environment exerts a causal infl uence upon the brain

and visual system. As we will see in the next chapter, the implications of

synapse strengthening from environmental stimuli, as well as the ability

The Visual System 89

of neuronal processes to perform alternate functions, are integral to an

evolutionary account of conscious visual processing and creative problem

solving in humans.

In this chapter, I built upon work of the previous chapters and showed

how the processes associated with vision in mammals comprise a hierarchically

organized system exhibiting the same kinds of properties of information

exchange, selectivity, and integration found in organisms in general.

I distinguished four levels of visual processing in animals: a noncognitive

visual processing, two cognitive/psychological forms of visual processing,

and a conscious cognitive visual processing that occurs at the highest level

of the visual hierarchy. Since in this project I am concerned mostly with

the progression from cognitive visual processing to conscious cognitive

visual processing, the relationship of these processes to one another, and,

ultimately, how conscious cognitive visual processing evolved from cognitive

visual processing, I showed that the visual systems of mammals function

so as to produce visual cognition.

Visual cognition is the phenomenal representation of some object in the

animal’s visual fi eld that is the result of the integration of modular visual

information received from that object in association with iconic memory,

attention, and the synchronous fi ring of neurons in the areas of the brain

relevant to the processing of the visual percept. Special attention was paid

to visual modularity, which refers to the fact that the visual system is made

up of distinctly functioning and interacting modules or areas having

evolved to respond to certain features of an object in typical environments,

and visual integration, which refers to a neurobiological process or set of

processes that bind together the relevant information gleaned from visual

modules/areas into a coherent cognitive representation of some object,

enabling an animal to negotiate typical environments. In the next

chapter—which is really the heart of the book—I trace the evolution of

the visual system from organisms that developed a light/dark sensitivity

area to humans who are capable of the complex activities involved in scenario

visualization, one form of conscious cognitive visual processing.

In the fi rst chapter, it was made clear that organisms exchange information

with environments, that these environments can comprise interactions

within the organism as well as interactions with the external world

of the organism, and that environmental pressures can be described in

terms of information that is exchanged within the organism and/or

between environment and organism. Such exchanges with environments

also affect the visual system. This is the last section of this chapter, and

it acts as an important segue into the next chapter where I deal with

the evolution of the visual system. This is so for two reasons: it is the

internal environment of the cell related to genetic mutations in cell differentiation

where evolution principally takes place, and, it is the external

environment of the organism as a whole that acts as the condition for

the possibility of the evolution of the visual system and scenario visualization.

In this section, I describe fi rst how the internal environment of the organism’s processes and subsystems has an effect upon the visual

system. Then, I describe the effects of the external environment upon

the visual system.

The following examples all illustrate that the workings and interactions

of the brain act as internal environmental pressures that affect the processes

and functioning of the visual system. First of all, with the discovery

of HOX genes it has been shown that much of an organism’s phenotypic

characteristics are under direct genetic control. For example, moving

around, replacing, or taking out certain Drosophila (fruit fl y) HOX genetic

sequences produces mutated and monstrous results—antennae grow out

of abdomens, appendages grow out of heads, or basic parts are missing

(Nüsslein-Volhard & Wieschaus, 1980). The visual system is no exception

to this rule, as researchers have been able to adjust gene sequences related

to the visual systems of Drosophila, fi sh, amphibians, mice, and hedgehogs

(Chitnis, 1999; Maconochioe, Nonchev, Morrison, & Krumlauf, 1996;

Belloni et al., 1996; Goddard et al., 1996).

The important point to realize is that the experimenter’s adjustments to

the genetic code are directly analogous to the natural mutations that occur

on a regular basis in the reproductive lives of organisms. During cell division

and reproduction, genes go about their functioning in their own

chemical environments of the cell. What takes place in those environments

directly affects genetic formation in terms of mutant alleles (alternate

forms of a particular gene). When neurons differentiate, there are

natural genetic mutations that constantly occur because of chemical infl uences

upon chromosomal chains. In fact, if it were not for the regular

occurrence of mutant alleles, every living thing would look exactly like everything

else (Mayr, 1976; Eldredge, 2001). The processes associated with

mutant allele formation—rife with internal environmental pressures—

account for the phenotypic diversity of living things. In the next chapter,

before tracing the evolution of the brain and visual system, I talk more

about genetic mutations in relation to the environments of organisms.

Another example illustrating the effect of internal environmental pressures

upon the visual system has to do with neurulation, the successful

positioning of the various kinds of neurons in their appropriate spots

throughout certain developmental stages. Formation of the neural tube,

some three weeks after conception in humans, depends on a fairly precise

sequence of changes in the shape of individual cells, as well as the connections

of cells to one another. Timing is a factor in the process, since

neurulation must be coordinated with the ectoderm (outer layer of cells)

and mesoderm (middle layer of cells) of the neural tube. At the molecular level, neurulation is dependent upon specifi c sequences of gene expression

that are affected, to a large degree, by the positions and local chemical

environment of the cell. For example, a defi ciency of folate—a chemical

found to be important in the healthy development of the neural tube—

may cause a malformation of the retina, which develops out of the ectoderm.

This is one reason why doctors will ask women to take certain doses

of folate during pregnancy.

A fi nal example that illustrates the effect of internal environmental pressures

upon the visual system has to do with the neurotrophic theory, that is,

the idea that neurons compete for space in their own environment of the

brain (Reichardt & Fariñas, 1997). It is well-known that the developing

nervous system overproduces connections in great excess during development.

Through programmed cell death, as well as through a competition

for space, neuronal connections are pruned away as the nervous system

continues to develop. Hubel & Wiesel (1962, 1968) coined the term binocular

rivalry, which has to do with the inputs from both eyes in layer IV

competing for space (Myerson, Miezin, & Allman, 1981; Lumer, 2000).

Interestingly enough, this internal environmental confl ict is necessary for

the appropriate development and functioning of the nervous system (Craig

& Lichtman, 2001; cf. Lumer, Friston, & Rees, 1998; Zhang, Tao, Holt,

Harris, & Poo, 1998). Other forms of visual competition have been documented

(e.g., Antonini & Stryker, 1993; Blake & Logothetis, 2002; DiLollo

et al., 2000). Also cats, rats, and birds that have had their eyes occluded or

removed in early development show evidence of synaptic competition for

the unused visual space (Shatz & Stryker, 1978; Antononi & Stryker, 1993).

It is important to note that overproduction and competition were the fi rst

two observations Darwin (1859) made concerning species in general that

led to his formation of evolutionary theory.

There is a time frame in the development of the nervous system known

as a critical period. During this critical period, it is important for the nervous

system to receive information from the external world so as to aid in

appropriate neuronal maturation and synapse formation. As Zigmond

et al. (1999, p. 637) make clear: “During a critical period, the pathway

awaits specifi c instructional information, encoded by impulse activity, to

continue developing normally. This information causes the pathway to

commit irreversibly to one of a number of possible patterns of connectivity.

If appropriate experience is not gained during the critical period, the

pathway never attains the ability to process information in a normal

fashion and, as a result, perception or behavior is permanently impaired.”

It is widely agreed that a combination of natural genetic factors (nature) as well as environmental stimuli (nurture) are necessary for normal, healthy

nervous system development. Notably, even though it is the genetic blueprint

that acts as the formal guideline by which differentiated neurons

move into position in development, there can be material factors in the

environment of the neuron—like some kind of lesion or another mutated

neuron—that prevent the neuron from achieving its blueprinted designation.

It is not only the environment of the neuron but also the external

environment of the organism that affect the development of the nervous

system. For example, Bear et al. (2001) note that a lack of appropriate

nutrition, socializing, and sensory stimulation can contribute to the malformation

of dendritic spines, a key factor in mental handicaps.

The sensory pathways from one brain region to the next are organized

in such a way that neighboring groups of neurons maintain the spatial

relationship of sensory receptors in the periphery of the body. In fact, the

olfactory, visual, and somatosensory systems share the common feature of

topographic mappings of sensory surfaces, as well as parallel processing,

cortical modules, multiple cortical representations, and synaptic relays in

the dorsal thalamus. Topographical organization is an important way of

conveying information about the world to the nervous system. In essence,

the sensory pathways in the brain topographically refl ect the spatial relationships

of the environment (Kandel et al., 2000; Kosslyn, Thompson,

Kim, & Alpert, 1995). What this suggests is that the environment determines,

to a great extent, what we cognize. This has caused Sekuler & Blake (2002, p.

26) to claim that the “information picked up by the senses is not merely

a series of unrelated, incoherent data. Instead, sensory information closely

conforms to predictable, structured patterns. These patterns arise from the

very nature of the physical world itself, the world our senses have evolved

in.” Sekuler & Blake (2002, p. 168) also claim: “Organization in perception

mirrors the organization of real objects as they actually exist. The correspondence

between perceptual experience and the objects represented in

that experience is not accidental. After all, the visual system did evolve for

a purpose, namely to inform one about the objects with which one needs

to interact.”

The Gestalt psychologists noted that the visual system has built-in

mechanisms whereby the visual scene is grouped according to the following

principles: closure, the tendency of the visual system to ignore

small breaks or gaps in objects; good continuation, the tendency to group

straight or smoothly curving lines together; similarity, the tendency

to group objects of similar texture and shape together; and proximity,

the tendency to group objects that are near to one another together. Numerous studies have ratifi ed these principles as refl ective of the visual

system (Wertheimer, 1912, 1923; Brunswik & Kamiya, 1953; Kanizsa,

1976, 1979; Peterhans & von der Heydt, 1991; Gray, 1999; Sekuler &

Blake, 2002). These mechanisms can work only if the environment actually

displays the features on which the visual system is capitalizing.

There must be these kinds of regularities out there in the world, or else

it seems these principles would not be able to be delineated. Over 100

years ago, James (1890, p. 4) noted that mind and world “have evolved

together, and in consequence are something of a mutual fi t,” and the

Gestalt principles underscore this mutual fi t. Further, in reference to the

second chapter, where I dealt with metaphysical and epistemological

forms of emergence, this apparent mutual fi t of mind and world underscores

the argument from miracles. One might argue that it would certainly

be miraculous for the Gestalt psychologists to delineate their

principles if there were not this mutual fi t between mind and some

actually existing environment in which the mind fi nds itself.

It also has been shown that neuronal size and complexity—as well

as numbers of glial cells—increase in the cerebral cortices of animals

exposed to so-called enriched environments, that is, environments where

there are large cages and a variety of different objects that arouse curiosity

and stimulate exploratory activity (Diamond, 1988; Diamond &

Hopson, 1989; Mattson, Sorensen, Zimmer, & Johansson, 1997; Receveur

& Vossen, 1998). In these environments, it is important that animals

be exposed to objects having a wide variety of shapes, colors, and sizes

because there seems to be a close correlation between seeing these kinds

of objects and brain development. From such data, we can infer that

experiences in environments are refl ected to some degree in the structure

of our brains.

Add to this the most recent data suggesting that regions of the brain can

be trained, through mental and physical exercises, to pick up tasks from

other regions. The evidence for this comes from stroke patients who regain

the ability to speak, musicians who relearn how to play an instrument

after nerve damage, and cerebral palsy patients who learn to perform

activities long thought impossible to perform (Holloway, 2003; van Praag,

Kempermann, & Gage, 2000; Schwartz & Begley, 2002). Not only does this

suggest that certain brain processes are highly malleable and fl exible

(Malenka & Siegelbaum, 2001; Singer, 1995) but it again points to the fact

that the external environment exerts a causal infl uence upon the brain

and visual system. As we will see in the next chapter, the implications of

synapse strengthening from environmental stimuli, as well as the ability

The Visual System 89

of neuronal processes to perform alternate functions, are integral to an

evolutionary account of conscious visual processing and creative problem

solving in humans.

In this chapter, I built upon work of the previous chapters and showed

how the processes associated with vision in mammals comprise a hierarchically

organized system exhibiting the same kinds of properties of information

exchange, selectivity, and integration found in organisms in general.

I distinguished four levels of visual processing in animals: a noncognitive

visual processing, two cognitive/psychological forms of visual processing,

and a conscious cognitive visual processing that occurs at the highest level

of the visual hierarchy. Since in this project I am concerned mostly with

the progression from cognitive visual processing to conscious cognitive

visual processing, the relationship of these processes to one another, and,

ultimately, how conscious cognitive visual processing evolved from cognitive

visual processing, I showed that the visual systems of mammals function

so as to produce visual cognition.

Visual cognition is the phenomenal representation of some object in the

animal’s visual fi eld that is the result of the integration of modular visual

information received from that object in association with iconic memory,

attention, and the synchronous fi ring of neurons in the areas of the brain

relevant to the processing of the visual percept. Special attention was paid

to visual modularity, which refers to the fact that the visual system is made

up of distinctly functioning and interacting modules or areas having

evolved to respond to certain features of an object in typical environments,

and visual integration, which refers to a neurobiological process or set of

processes that bind together the relevant information gleaned from visual

modules/areas into a coherent cognitive representation of some object,

enabling an animal to negotiate typical environments. In the next

chapter—which is really the heart of the book—I trace the evolution of

the visual system from organisms that developed a light/dark sensitivity

area to humans who are capable of the complex activities involved in scenario

visualization, one form of conscious cognitive visual processing.