Consciousness in Perception and Perceptual Memory - Essay Example

Consciousness in Perception and Perceptual Memory Introduction Psychological researchers over time have focused research in the field of perceptual memory, especially the role of consciousness in enhancing human memory of perceived stimulus. George Sperling is one such remarkable researcher whose works on the field of neuropsychology have continued to provide invaluable instincts in the memorization process and how consciousness influences the process. The paper will focus on Sperling’s experiment regarding the duration of stimulus generation, induced consciousness and perceptual memory with a view to understanding the correlation between the three processes. Sperling’s Experiment George Sperling is acknowledged for the discovery of iconic memory. He carried out a classical experiment to determine memory span. In doing so, he carried out seven experiments. The first three were a number of immediate memory, exposure duration and partial report experiments. The rest were decay of available information, exposure parameters, letters and numbers, and order of report. In Sperling’s procedure, he used five subjects who went through twelve sessions. In his procedure, Sperling used a tachistoscope. The subjects were shown an array of letters arranged in matrix form. Each subject was shown the letters in a short span of 5-500ms. Thereafter, each reported how many letters they could recall. From the results, Sperling noted that the subjects recalled 4.5 items on average. This was irrespective of stimulus duration or display size. This was known as the immediate memory span. In the partial report experiment, Sperling cued the subjects at random. He used an auditory signal in this experiment. A high tone indicated that the subjects were to report letters in the top row. Medium tone indicated report of middle row and low tone indicated report of bottom row.pon asking them to recall the subsets, the results were different. Each subject could remember 75-90% of the items. This meant that much more information was available to the subject after stimulus display. 75% contrasted with the 33% from the full report experiment. Sperling went on to alter the duration between stimulus offset and cue presentation. As the interval increased, there was a decline in the superiority of partial report. He noted equality in the two experiments at a one second cue interval. Sperling also noted change in strategy by the subjects with increasing cue interval. With longer cue delays, subjects anticipated where the cue would show up. Consequently, there was better remembrance of certain stimuli and poorer recollection of other stimuli. From his experiments, Sperling made various conclusions. He concluded that sensations made from a physical stimulus outlast the physical duration. This implies memory storage. This meant that what one could not recall was not lost. In fact, their memory stored it. For this reason, a subject could recall more things in the partial report experiment. Sperling concluded that man has visual memory storage. This visual memory storage is what contains a mental image of what we see. However, these images quickly fade away. For this reason, the subject could only report 4.5 items. After that, the subject could not recall anything else. This is attributed to the fading of memory. He also concluded about the sensory memory. This memory has the capability to hold large amounts of memory, but for a short period. He also acknowledged iconic memory as a property of memory storage. Block’s Overflow Interpretation Based on Sperling’s experiment, Ned block came up with the concept of overflow. The overflow argument suggests that all the 12 items had a conscious representation. The subjects could recall one letter from the three rows. Nevertheless, subjects could recall whatever letter they were asked upon post-stimulus cueing. According to Block’s interpretation, there is an overflow of information from working memory. In other words, one sees a full display of letters but only reports a limited amount. Block suggests that one can be in phenomenally conscious states without having cognitive access. Philips Article’s Description of the Visual Bounce Post-Diction Experiment Post-diction experiments assert that our conscious formation is derived from interplay of information in the brain. Philips documents that this is influenced by two types of stimulus: target and modulator stimulus. The modulator stimulus is aimed at affecting the target stimulus. This leads to additional information that influences the past information we have previously received. Philips aims at evidencing that auditory stimulus has the propensity to modulate visual stimulus. Consequently, the post-diction experiment avows that 300ms is the timescale for post-diction experiment. This is aimed at affirming Sperling’s hypothesis: cue- sensitivity of initial display of perception. Also Philip aims at assessing the overflow arguments as stipulated by Sperling in his model (Philips, 386). Visual bounce post- diction experiment appreciates the modulation of the perception rather than its degeneration. This experiment evaluates how sound affects the visual perception of an image. It entails the presentation of subjects with two dots and latter the inculcation of sound. The dots are either perceived as bouncing on each other, or reversing direction before streaming together. Upon application of sound, subjects reported that the dots seem to bounce rather than stream. This serves as the basis of assessing casualty and the relationship between visual and auditory stimulus. Post-diction experiments are able to reach the past conscious and modulate high level precepts. Auditory content over a long period of time is attributed to influence the visual bouncing. Moreover, visual bounces are not influenced by acoustic property of the sound. However, visual bounce is influenced by auditory stimulus that does not affect the consciousness (Philips, 389). Why Philips Thinks That Such Experiments Undermine Overflow Interpretation With Reference to the Stalinesque Model of Post Diction Stalinesque model is aimed at illustrating the stream of consciousness by portraying impediment in conscious knowledge. This delay in the conscious perception is what is described as Stalinesque. Tye uses temporal experiences to try and illustrate the post- diction findings. Tye uses A and B as prototypes hence illustrate the backward looking post-diction experiment. He asserts that A has to precede B and B consequently influences A by modulating A. This means that for A to be perceived, it has to look back at B. it is described as the simplest overflow interpretation of perceptions (Phillips, 392). The use of lag illusion and color phi is inculcated to explain the Stalinesque model. This is where a subject views different color by moving a disc within the visual range. Flash light illustrates how light lags behind a spinning ring depending on direction. This affirms the capability of our brains to look into the future. It means that we are able to perceive events in the future prior to their occurrence. This is in turn referred to as temporal consciousness since the temporal is responsible for memory (Phillips, 393). Philips thinks that this experiment underpins overflow information since it relies on temporal consciousness. This is since he perceives this as more of iconic memory. The iconic memory is what aids in the post- diction perception. This enables one to perceive the future while still in the present time. This is since it inculcates visual cognition and apprehension span and does not just rely on temporal consciousness. Stalinesque undermines overflow interpretation as it focuses on introspective judgments. Consequently, there’s no distinction of information from sensory persistence hence undermining overflow interpretation (Phillips, 394). Block’s Rejection of Counter Argument Block gives several reasons against the counter-arguments of his overflow argument. His critics think that supporting the overflow argument means embracing the idea of inaccessible consciousness. Inability to report does not mean inability to access information. Another reason Block gives is in relation to unconscious images. His critics believe that these images form the default view that is inerasable. In an experiment, subjects are given rectangular gradient patches in a circle. A grey interstimulus mask is introduced. Thereafter, the one of the rectangles’ orientation is changed or not. This can be classified as a phenomenally conscious experience where the stimulus persists for some time. This is after the actual stimulus is absent. Block argues that the subjects could be right in saying that they saw all rectangles. One counter argument dismisses this. It says that it’s impossible for the subjects to recall the rectangles and their orientation. Block says that such an argument lacks authority. He argues that a phenomenally conscious experience occurs. Thus, it is true that subjects see all rectangles only that they cannot report. Thus, Block defends his overflow argument. Conclusion Sperling’s experiment provides a good basis for understanding and undertaking further research on the correlation between consciousness and perceptual memory. Discussions regarding this experiment continue to generate important input into the study of human memory, which all clearly indicated the significant role of awareness in the process. Research should therefore focus on strengthening the findings of this experiment while eliminating any weaknesses of the experiment to draw correct conclusion on the discussion. Work cited Phillips, Ian. “Perception and Iconic memory: What Sperling Doesn’t Show”, Mind Lng. 26; (2011): 381- 412. Web. 15 Feb 2012. Read More