Visual Cognition-in 1814 words! - Charles Brand

8/8/2019 Visual Cognition-in 1814 words! - Charles Brand

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In recent years, the study of cognitive psychology has become influenced by neuroscience and neuropsychology. What

has this type of research told us about our capacity for attention, or visual perception?

Introduction

Cognitive psychology is generally agreed to be concerned with the scientific study of processes in

the mind that help us to make sense of our external world. It is also concerned with how these processes

function and how we appropriate responses to our world (Solso, 2001; Eysenck & Keane, 2005).

Cognitive science is a multi-disciplinary science that includes areas of computer science, artificial

intelligence, philosophy, linguistics and neuroscience (Wylie & McMahon, 2010). Within the neuroscientific

area are; neuropsychology, cognitive neuropsychology and cognitive psychology. Cognitive

neuropsychology is the closest relative to cognitive psychology as it developed from a merging of

neuroscience and cognitive psychology (Solso, 2001 p.38). Cognitive neuropsychologists model the

workings of a normal brain and compare this to the functionality of an impaired brain. Neuropsychological

research conclusions can have a direct influence upon the field of cognitive psychology; they can thus be

though of as complementary disciplines. (Ellis & Young, 1996, p.24).

Getting the Bigger Picture

While cognitive psychology approaches this examination by way of observation (Quinlan &

Dyson, 2008), the neuropsychological approach consists of observing the physiological activity in the

brain during cognitive tasks. One of the most influential technological areas to have had a direct impact

on the mutual advancement of disciplines interested in neurological and neuropsychological cognitive

function is that of neurophysiological sensing. The lesion method is widely used in neurological research

and Damasio (2000, p. 77) defines the purpose of a lesion research as relating a specific type of

behaviour within a neuropsychological experiment with the site of the lesion. While of use to the cognitive

neuropsychologist in terms of correlating physiological location and elements of cognitive function, lesion

based studies do not tell much about the cognitive processes at work (Ellis & Young, 1996; Groome et al,

1999). Lesion studies have however given significant weight to the assertion that; functional brain

deficits cannot necessarily be attributed to particular regions of the brain where lesions are located

(Steinberg & Mio, 2008). This is of importance, as it highlights the fact that that in order for the brain

(from a neuropsychological perspective) to be able to perform functions of the mind (from a cognitive

psychological perspective) such as problem solving, abstraction, language acquisition and visual

interpretation, etc. we must acknowledge that many disparate physical parts of the brain are involved

(Damasio, 2000, p. 78; Steinberg & Mio, 2008, p. 207).


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The goal of neurophysiological sensing is to represent areas of elevated glucose and oxygen

levels as well as increased blood flow. All cognitive activity requires increased metabolic activity, so by

providing an accurate representation of this increase we can view particular cognitive processes occurring

at specific locations in the brain (Solso, 2000, p. 56). Consequently, we can see neurophysiologicalimaging is useful for determining functional as well as structural information.

Positron Emission Tomography (PET) brain scanning involves the introduction of minute amounts

of radioactive material into the bloodstream which are tracked in the brain in order to identify areas of

increased neural activity. Magnetic Resonance Imaging (MRI) and Echo-Planar MRI (EPI) also provide a

picture of the brain. Both utilise powerful magnets that align the hydrogen molecules found in water. The

difference in densities between the hydrogen atoms and other tissue are then represented to build a

graphical representation of the brain. Images produced by both MRI and EPI have been prone to blurring

due to patient movement during the imaging process but this problem is currently being addressed (New

Capabilities, 2006) and makes available previously unavailable cohorts of subjects for examination e.g.

Parkinson's patients and children who are unable to remain stationary during the imaging process. As we

have shown, lesion studies and imaging techniques provide cognitive scientists with powerful physical

evidence that can be related, in particular ways, to behaviour and function deficit in humans. However,

from a perspective of cognitive psychology this information must be regarded as partial in the overall

view of behavioural cause and effect the map, but not the territory.

Visual Perception - The Current Picture

An early theoretical position on the nature of visual perception was known as intelligent

perception; a precursor to constructive theory. Constructivist perception theory holds that perception

takes place within an array of cognitive processes (Coren, Ward & Enns, 1994, p. 14). Rock (1981) found

that the role of attention played a significant part in the ability of subjects to process a complex visual

form. This integrative approach holds that several elements of our cognition (attention and visual

perception) interact to construct our final percept.

Palmer's work involved testing the parsing paradox i.e. whether we recognise the parts of our

environment and build up a representation through our vision (bottom-up processing), or begin with a

complete representation and progress to individually recognise the individual elements (top-down

processing). This is described by Palmer as being part of the overall process of perceptual organisation

(cited in Weiner et al. 2003, p. 179). The dichotomous processes of the parsing paradox have been

theorised by Palmer to occur simultaneously, and as he demonstrated, context plays an important role


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during this interpretive process (Palmer, cited in Solso, 2000, p.121). He showed that in a simple line

drawing, facial features (ear, nose eye and mouth) are easily recognised when shown in context of a

complete facial representation but are less so when shown in isolation. However, once the simple line

drawings of the isolated features are more elaborately represented they become more easily identifiablethus demonstrating the bottom-up and top-down principles at work within a contextual framework (cited

in Solso, 2000, p.121).

As the neurological load capacity and exact adherence requirements of template matching theory

became more problematic (Solso, 2000), Biederman proposed a much more flexible and pragmatic

approach. Intelligent assembly of his geons (geometrical ions) allows for the fabrication of complex

shapes from a library of 24 simple and distinct forms (Solso, 2000, p.125). In terms of contextual

influence, Biederman's experiment (cited in Weiner et al. 2003, p. 1999) showed that subjects who were

presented with photographs containing randomly arranged objects took longer and were less accurate in

their recognition. This demonstrates that we seek appropriateness when attending to objects within our

visual field. This work along with that of Rock and Palmer all contributes to constructivist theories of

visual perception; they are driven by the belief that complex higher cognitive processes are paramount in

our attempts to accurately perceive the world.

Direct perception conversely- holds that the stimulus contains all the information required to

formulate our visual perception, and that the role of cognition and learning is negligible (Solso, 2000).

Direct perception could be seen to be closely aligned with an ecologically based psychological outlook

insofar as it stresses the connective properties between the environment and it's inhabitants. J.J. Gibson

was a leading proponent of this ecological stance and he argued that it was our relationship with our

environment as well as the available stimuli garnered by our senses that enabled us to form our percepts

(Galotti, 2009). This relationship underlines an important aspect of Gibsonian thought; that of

affordances. Best described by Michaels & Carello (1981) as the acts or behaviours permitted by objects,

places and events (cited in Galotti 2009, p. 89) affordances are the properties of objects in our

environment that are presented to our senses and guide our interaction and behaviour with those objects

(Galotti, 2009). Therefore, according to Gibson the reason we do not swim in a chair and sit on a lake of

water is because we pick up on the affordances these objects offer, hence our action and perception are

inextricably linked.

Another principle within direct perception is that of invariance, which holds that certain properties

of a stimulant object remain fixed even though the image projected onto the retina may change

constantly due to movement of the observer (Coren, Ward & Enns, 2000; Galotti, 2008). In the


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Gibsonian tradition this highlights the importance of the relational value between stimuli e.g. the same

piece of music can be recognised even when played in two different keys because the main elements (the

notes) have remained invariant. The influence of invariance upon visual perception was strongly

supported by experiments conducted by Johansson (cited in Galotti, 2008, p.87). Lights were fitted to ahuman subject at particular points along the body and they were dressed in black and placed against a

black background. Subjects were then videoed while performing a series of actions. Study participants

instantly identified different actions from the video when they could only see the movement of the lights.

This demonstrated the possibility that certain patterns of motion were susceptible to some degree of

invariance. From a neuropsychological perspective, the concept of invariance in cognitive psychology is

highly relevant. Common fundamental organisational structures between normal human subjects are the

bedrock upon which modelling, the hypotheses for neurophysiological experimentation, is formed

(Temple, 1997). Subsequently, both disciplines gain from this shared conceptualisation.

The view that all required information for forming percepts is one shared by the computational

theories of perception. Computational theory differs from direct perception however in that it posits that

simple dimensions such as line endings, edges etc. can be pieced together and synthesised in order to

present a conceptual picture of the world (Coren, Ward & Enns, 2008). Marr (cited by Galloti, 2009, p.77)

posits that there are several sequential steps in the process of visual perception e.g. colour analysis,

movement analysis etc. These steps, or modules, operate autonomously, without influence from other

modules in terms of input and output and do not take regard of real-world knowledge . Thus the viewer

builds up a partial representation from the arriving stimuli and this can be viewed as a bottom-up

process. Once the building process reaches a certain point of completion; real-world knowledge or other

subjective elements (top-down processes) are incorporated to present the final perceptual experience.

Here we see echoes of neurophysiological rationale previously mentioned and posited by Damasio (2000)

that concurs with a cognitive psychological approach to visual perception.

Conclusion

From a cognitive neurophysiological perspective, in the case of visual perception, we have shown

that some of the approaches taken by cognitive psychology have more to offer than others. Gibson's

direct perspective has been criticised for not being sharply enough defined in relation to the concepts of

variance and affordances (Galotti, 2008), and without sufficiently defined concepts where do cognitive

neurological scientists begin to investigate possible physiological associations? Computational

perspectives have more credible common ground and share the concept of modularity in visual


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perception purported by Marr (cited by Ellis and Young, 1996, p.61), which complements a neurological

approach insofar as it supports a more isomorphic hypothesis of brain function. What has become clear

then is that there is a bi-directional flow of influence between the areas of cognitive neuroscience and

cognitive psychology, and that attention can be demonstrably shown, through neuroscience, to have astrong bearing on our visual percept.


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References

Coren, S., Ward, L.M., Enns, J.T. (1994). Sensation and Perception. Texas, U.S.A.:Harcourt Brace &

Company

Damasio, H. (2000). The Lesion Method in Cognitive Neuroscience. In F. Boller & J. Grafman Eds.Handbook of Neuropsychology: Volume 1 Section 1. Introduction. (2 nd ed.)(pp. 77-102)

Amsterdam, Netherlands:Elsevier Science.

Eysenck, M.W., Keane, M.T. (2005). Cognitive Psychology: A Student's Handbook. (5 th ed.). New

York, U.S.A.:Psychology Press.

Galotti, K.M. (2009). Cognitive Psychology: In and Out of the Laboratory. Belmount, California:Cengage

Learning

Groome, D., Dewart, H., Esgate, A., Gurney, K., Kemp, R., Towell, N. (1999). An introduction to

cognitive psychology: processes and disorders. Cornwall, Great Britain:Psychology Press.

Quinlan, P., Dyson, B. (2008). Cognitive Psychology . Lombarda, Italy:Pearson Education.

Weiner, I.B., Healy, A.F., Proctor, R.W., Schinka J.A. (2003). Visual Perception of Objects. In. I.B.

Weiner, A. F. Healy, D.K. Freedheim, & R.W. Proctor Eds. Handbook of Psychology:

Experimental psychology Volume 4 (pp. 179-212) New Jersey, U.S.A.:John Wiley and Sons.

Rock, I. (1981). The Effect of Inattention on Form Perception. Journal of Experimental

Psychology:Human Perception and Performance, (7)2, 275-285.

Rock, I. (1983). The Logic of Perception Massachusetts, U.S.A:M.I.T. Press.

Solso, R.L. (2001). Cognitive Psychology . (6 th ed.). Massachusetts, U.S.A:Allyn & Bacon.

Steinberg, R., Mio, J. (2008). Cognitive Psychology. Belmount, California:Cengage Learning

St. Joseph's Hospital and Medical Center (2006, January 5). New Technology Enhances MRI Capabilities.

ScienceDaily. Retrieved December

http://www.sciencedaily.com/releases/2006/01/060105083855.htm

Temple, C. (1997). Developmental cognitive neuropsychology. East Sussex, U.K.:Psychology Press

Wylie, J., McMahon, C. (2010) Oscail Psychology 4:Cognitive Psychology Dublin, Ireland:Oscail.
http://www.sciencedaily.com/releases/2006/01/060105083855.htmhttp://www.sciencedaily.com/releases/2006/01/060105083855.htm

Visual Cognition-in 1814 words! - Charles Brand

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