Chapter notes

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20 Jun 2011

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Roshan Singh
Mr. Joordens
Chapter 9 Notes
Historically, people have taken 3 philosophical positions about the nature of consciousness:
Consciousness is not a natural phenomenon. (Natural phenomena are those subject to the laws of
nature that all scientists attempt to discover: laws purely involving matter and purely physical
forces.) It is supernatural and cannot be understood by the human mind.
Consciousness is a natural phenomenon but also that, for various reasons, we cannot understand
it. So, consciousness exists because of the nature of the human brain, but just how this occurs is
People are indeed conscious; that this consciousness is produced by the activity of the human
brain and that there is every reason for us to be optimistic about ability to understand this
Donald Hebb supported the 3rd position and stated that, “consciousness, a variable state, is a present
activity of thought processes in some form; and thought itself is an activity of the brain. He rejected the
notion that concepts like consciousness were nothing but neural impulses.
To understand consciousness, we must not mix it up with processes such as perceiving, remembering or
thinking. Consciousness is the awareness of these processes, not the processes themselves. In other words,
it is a characteristic that exists in addition to functions such as perception, memory, thinking and planning.
The word consciousness is a noun, but it does not refer to a thing as life is a noun as well but you dont see
scientist looking around for life. Instead, they study characteristics of living organisms. Similarly,
consciousness doesnt exist. Instead, humans have the ability to be conscious.
Consciousness is a private experience, which cannot be shared directly. We experience our own
consciousness but not of others. Consciousness is primarily a social phenomenon. (author of book
Verbal communication allows us to express our needs, thoughts, perceptions, memories, intentions, and
feelings to other people. All of these accomplishments require 2 general capacities:
We must be able to translate private events (needs, thoughts, and other processes) into symbolic
Our words (or other symbols) must have an effect on the person listening.
We can make plan in words, think about the consequences of these plans in words, and use words to
produce behavioursall without actually saying the words. We think them. The brain mechanisms that
permit us to understand words and produce speech are the same ones we use to think in words.
The ability to communicate with ourselves symbolically gives rise to our consciousness. We are conscious
of those private events we can talk about, to ourselves or to other people our perceptions, needs,
intentions, memories and feelings.
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Roshan Singh
Mr. Joordens
Chapter 9 Notes
Cheesman and Merikle (1986) presented people with a word that was either congruent or incongruent
with the colour of a subsequent target. People were asked to name the colour of the target. They found that
incongruent primes produced a stroop-like interference even when the jumble of lines had interfered with
the ability to consciously identify the word. They used the same experiment with more regularity in terms
of colours so a person was able to predict that the same colour was likely to be shown again such as green
after green had been shown previously.
Conscious awareness has this property: We become able to describe, and thereby use, the psychological
events that are private to ourselves.
Animals have consciousness to but our ability to communicate symbolically far surpasses that of any
other species; thus, our consciousness is much more highly developed. But, the underlying brain
mechanisms, such as those of the explicit memory system, may be present in species closely related to
In order for a computer to be conscious, it would have to possess devices that enable it to perceive events
in its environment, think about these events, remember them, and so on. It would also have to
communicate symbolically with us describing its perceptions, thoughts, and memories. Furthermore,
when we described our own mental events, our words would have to evoke thoughts and perceptions in the
computer, just as they do in the brain of a human. In an abstract sense, many of the computers can serve as
metaphors for self-awareness.
Anderson and colleagues (1999) reported the case of 2 individuals who, before they were two years of
age, suffered damage to the prefrontal areas of the brain. Now, they have struggled making moral
decisions as to what is right and wrong in their life.
Thinking of consciousness as the result of the brains activity will most certainly help us understand the
phenomenon of consciousness.
Selective attentionThe process that controls our awareness of, and readiness to respond to, particular
categories of stimuli or stimuli in a particular location.
The process of selective attention determines which events we become conscious of. Attention may be
controlled automatically (when an intense stimulus captures our attention), instructions or by the demands
of the particular task we are performing. Attention to visual events in particular tends to act like a
spotlight that highlights the events within some spatially contained area.
Attention plays an important role in memory. By exerting control over the information that reaches short-
term memory, it determines what information ultimately becomes stored in explicit long-term memory.
But the storage of information in implicit memory does not require conscious attention. Not all of the
information we do not pay attention to is lost.
Broadbent (1958) suggests that the brain mechanisms responsible for conscious processing of this
information have a limited capacity. There is only so much information that these mechanisms can handle
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Roshan Singh
Mr. Joordens
Chapter 9 Notes
at one particular moment. Thus, we need some system to serve as a gatekeeper, controlling the flow of
information to this system.
Dichotic listeningA task that requires a person to listen to one of 2 different messages being presented
simultaneously, one to each ear, through headphones. Devised by Cherry (1953)
ShadowingThe act of continuously repeating verbal material as soon as it is heard.
The results suggested that a channel of sensory input can simply be turned off. Perhaps, neurons in the
auditory system that detect sound from the unattended ear are inhibited so that they cannot respond to
sounds presented to that ear.
Other evidence show that some information can break through into consciousness. Example: a person is
likely to remember the name that was uttered in the unattended ear or if it contained sexually explicit
words then they tend to hear them immediately. This indicates that even unattended information
undergoes some verbal analysis. If the unattended information is filtered out at some level, it must not
occur until after the sounds are identified as words.
McKay (1973) showed that words in the unattended ear can affect the sentence that was heard in the
attended ear.
Besides being able to notice and remember some characteristics of information received by the unattended
sensory channel, we are able to store information temporarily as it comes in.
Treisman (1960) showed that people can follow a message that is being shadowed even if it switches from
one ear to the other. As a result, even though an unshadowed message cannot be remembered later, it
produces some trace that can be retrieved if attention is directed to it soon after the words are presented.
The visual experiments have shown that we can successfully attend to the location of the information or to
the nature of the information.
Posner, Snyder, and Davidson (1980) had people watch a computer controlled video display screen. The
study showed that selective attention can affect the detection of visual stimuli: If stimuli occurs where we
expect it, we perceive it more quickly; if it occurs where we do not expect it, we perceive it more slowly.
Neurologically, in this case, the mechanism of selective attention sensitized the neural circuits that detect
visual stimuli in a particular region.
Inhibition of returnA reduced tendency to perceive a target when the targets presentation is consistent
with a noninformative cue. Usually, inhibition of return is tested with respect to spatial location and is
present when the target is presented several hundred milliseconds after the cue.
ODonnell and Pratt (1996) created their own rendition of the inhibition of return in their experiment.
Neisser and Becklen (1975) showed people a videotape that overlapped a basketball game and a hand
game. People could focus on either one but not both of them simultaneously.
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