Free Essays: Behavioral Science

The Attentional Blink
The Glutamate Theory of Schizophrenia
Non-intelligent Perception
Anxiety and the GABA-A receptor subunit
On The Theory-Ladenness of Observation
ECT in Depressed Older Adults
Daniel Dennett Indented?



The Attentional Blink

Attention seems to be intimately linked to consciousness. We cannot attend to something (be it a physical object or a thought) without at the same time being conscious about the object of attention. Thus, it seems reasonable that the neuronal substrates of attention correlate with those of consciousness. Given that all the information available from the retinas do not enter consciousness, and that that being attended to usually does, it seems like the study of visual attention may give a glimpse into the brain mechanisms of consciousness.

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The Glutamate Theory of Schizophrenia

Schizophrenia is a complex disease, which shows itself through what are called positive (Type I) and negative (Type II) symptoms. Type I symptoms include paranoia, hallucinations, thought disorders, and delusions (Carlson, 2001; Egan & Weinberger, 1997). Amongst the type II symptoms, we find flattened emotional response, social withdrawal, and reduced initiative (Carlson, 2001). In short, positive symptoms are recognisable through their presence, and negative symptoms by the absence of normal behaviours (Carlson, 2001). In addition, schizophrenic patients often show cognitive deficits (Kay & Sevy, 1990; as cited in Javitt & Zukin, 1991). It is estimated that about a half to one percent of the world’s population has schizophrenia (Carlson, 2001; Javitt, Sershen, Hashim, & Lajtha, 2000).

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Non-Intelligent Perception

Some researchers have proposed that perception is intelligent (e.g., Gregory, 2001; Kennedy,
2001; Rock, 2001); that some kind of intelligent inference is made every time an object in the
world is perceived, or, stated in other words, that perceiving is problem-solving, or
hypothesis-making (Gregory, 1980, 1997, 2001). Mayer, Caruso and Salovey (1999) list three
criteria an intelligence must meet “before it can be considered scientifically legitimate”. In the
present paper, three theories of intelligence in perception will be examined and criticised, and
they will all be shown not to follow the third criterion: “the abilities of the intelligence should
develop with age and experience” (Mayer, Caruso and Salovey 1999, p. 267), from now on
called C3. Several other objections to the notion of intelligence in perception will also be
raised. The three theories of Rock, Kennedy, and Gregory will be examined in turn, and
hopefully, their weaknesses will be exposed on the way. It will be concluded that the concept
of intelligent perception is not a useful one.

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Anxiety, the GABA-A receptor subunit isoforms, and benzodiazepines

Fear is a normal and adaptive response to threatening stimuli, but when fear is repeatedly
experienced inappropriately, it might be characterised as an anxiety disorder (Bear, Connors,
Paradiso, 2001); anxiety disorders are the most common of psychiatric disorders (Robbins &
al., 1984). To treat anxiety, several substances have been used: e.g., alcohol, opiates, and
barbiturates. Benzodiazepines (BZDs) were discovered in the early 1960s. They are
anxiolytic, and are not as addictive as other substances that have been used in the treatment of
anxiety (Leonard, 1992). BZDs are some of the most widely prescribed drugs (e.g., diazepam)
(Rosenzweig, Leiman, Breedlove, 1999), to treat anxiety disorders, epilepsy, and to induce
general anaesthesia (Williams & Akabas, 2000). BZDs work by increasing the channelopening
rates of the GABAA receptors (Study & Barker, 1981). As such, they have an effect
on balance and coordination as controlled by the cerebellum, on the limbic areas and cerebral
cortex (Leonard, 1992). In the present essay, GABA and the GABA-A receptor will be
introduced; the BZD receptor will be examined before the mechanisms of how BZDs bind to
it are discussed. Then, the BZD receptor will be revisited and examined in greater detail.
Several of the seven protein units that make up BZD-binding GABA-A receptors will be
discussed, but the focus will be on the a2 subunit. It will be argued that the a2 subunit of the
GABA-A receptor is important in mediating the anxiolytic effects of BZDs, and the
distribution of a2 subunits in the brain will be touched upon. The methods of investigation are
assessed before some side effects of BZD-treatment are considered. It will be concluded that
even though some caution should be applied in interpreting the data, different subunit
isoforms do seem to account for the different effects of BZDs. It will be suggested that these
findings provide guidelines for the development of newer drugs with fewer side effects.

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On the Theory-Ladenness of Observation

Whether or not observation is theory-laden has important bearings upon the way in
which we view the scientific process. If all observation is theory laden, we might have
to conclude that we can never discover truth; that the results of all scientific
endeavours are mere isomorphic representations of some postulated "real world," i.e.,
relativism. In this essay, I will address the question of whether observation is
necessarily theory-laden, by investigating the issue with respect to current
neurobiological understanding of the brain. Specifically, I will look at two arguments
(both due to Churchland) for the theory-ladenness of perception, the first coming
from connectionist modelling, thus being a theoretical approach, the other drawing
upon findings from biological neuroscience: that the brain has massive reentrant
connections going from the higher to the lower levels, all the way out to, for example,
the retina. An attack on the connectionist argument will be encountered, but shown to
be wrong. An attack on the second, biological argument will also be encountered,
arguing that the role of the massive reentrant connections in the brain is not to impose
a theory on the input, but is rather to make the peripheral systems part of higher
cognitive functions. Against this view, it will be argued that the two positions are not
mutually exclusive. Finally, the plasticity of the brain will be looked at. It will be
concluded that perception is theory-laden.

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Electroconvulsive Therapy in Depressed Older Adults

Depression is an illness. It is associated with a feeling of sadness that will not go away, a disinterest in life, and it might be followed by changes in sleep and appetite (Pace & Glass, 2001). It reduces people’s productivity, and the mortality rate is high (Doris, Ebmeier, & Shajahan, 1999); it is estimated that 5 million Americans over 65 years of age are depressed. This represents 12% of the population, but people in this age group account for 25% of all suicides (Zal, 1999). Major endogenous depression is a depression that occurs without any obvious cause, and is often recognised by its melancholic features (Rush & Weissenburger, 1994).

Electroconvulsive therapy (ECT) is a way of inducing grand mal type seizures electronically (Fink, 2000; Kelly & Zisselman, 2000), and since its development in 1938, ECT has shown itself a safe and effective way of treating, amongst other conditions, mania and depression (Cohen et al., 2000; Kelly & Zisselman, 2000; Wharton, 1968; Zorumski, Rubin, & Burke, 1988).

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Dennett Indented?

As humans, we often explain each other’s behaviours by alluding to mental states such as intentions, beliefs, and desires. These are all non-observable; they might be inferred from watching other people’s behaviour and making analogies with our own, private mental world.

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Short notes

Analogies and The Copycat Project


(c) Copyright 2004 Sten Morten Andersen,