Perception (Information Processing Theory)

Perception, or pattern recognition as it is sometimes known, alludes to the ascription of significance to environmental stimuli apprehended via the faculties of sense. For a given stimulus to be duly perceived, it is prerequisite that it be retained within one or more of the sensory registers and subsequently juxtaposed with pre-existing knowledge residing within Long-Term Memory.

Gestalt theory, a nascent cognitive paradigm, posited a challenge to numerous presuppositions inherent within the doctrine of behaviourism. Albeit the Gestalt theory no longer maintains unassailable currency, it proffered salient principles which find resonance in contemporary conceptualisations of both perception and learning. An exposition of this theory shall ensue, followed by a discourse on perception from an information processing vantage.

The Gestalt movement had its genesis with a small coterie of psychologists in early twentieth-century Germany. In the year of Our Lord 1912, Max Wertheimer penned an article concerning apparent motion. This article, whilst significant amongst German psychologists, exerted no influence in the United States, where the Gestalt movement was yet to commence. The subsequent publication in English of Kurt Koffka’s 'The Growth of the Mind' (1924) and Wolfgang Köhler’s 'The Mentality of Apes' (1925) did assist the Gestalt movement in its dissemination to the United States. Many Gestalt psychologists, including Wertheimer, Koffka, and Köhler, eventually emigrated to the United States, where they applied their notions to psychological phenomena.

In a typical demonstration of the perceptual phenomenon of apparent motion, two lines, situated closely together, are exposed successively for a fraction of a second, with a brief temporal interval intervening between each exposure. An observer perceives not two lines, but rather a solitary line moving from the line exposed first towards the line exposed second. The timing of this demonstration is of critical import. Should the temporal interval between the exposure of the two lines be excessively protracted, the observer shall perceive the first line and then the second, but no motion. Conversely, should the interval be unduly abbreviated, the observer shall perceive two lines juxtaposed, but likewise without any motion.

This apparent motion is known as the phi phenomenon, and it doth demonstrate that subjective experiences cannot be elucidated by reference to the objective elements involved. Observers perceive movement, notwithstanding the absence of any actual movement. Phenomenological experience (apparent motion) doth differ from sensory experience (exposure of lines). The endeavour to explicate this, and related phenomena, did lead Wertheimer to challenge psychological explanations of perception as the summation of one’s sensory experiences, inasmuch as these explanations did not take into account the unique wholeness of perception.

Meaningfulness of Perception

Imagine a woman, christened Betty, who stands at a height of five feet. When we observe Betty from a distance, our retinal image is considerably smaller than when we observe Betty at close quarters. Yet Betty remains five feet in stature, and we are cognisant of this fact, irrespective of her distance. Albeit the perception (retinal image) doth vary, the meaning of the image remaineth constant.

The German term 'Gestalt' doth translate as 'form,' 'figure,' 'shape,' or 'configuration.' The very essence of Gestalt psychology is that objects, or events, are viewed as organised wholes (Köhler, 1947/1959). The basic organisation doth involve a figure (that upon which one doth focus) against a ground (the background). That which is meaningful is the configuration, and not the individual parts (Koffka, 1922). A tree is not a haphazard assemblage of leaves, branches, roots, and trunk; it is a meaningful configuration of these constituent elements. When viewing a tree, individuals typically do not focus upon individual elements, but rather upon the whole. The human brain doth transform objective reality into mental events organised as meaningful wholes. This capacity to view things as wholes is an innate quality, albeit perception is modified by experience and training (Köhler, 1947/1959; Leeper, 1935).

Gestalt theory originally applied to perception, but when its European proponents came to the United States they discovered an emphasis on learning. Applying Gestalt ideas to learning was not difficult. In the Gestalt view, learning is a cognitive phenomenon involving reorganising experiences into different perceptions of things, people, or events (Koffka, 1922, 1926). Much human learning is insightful, which means that the transformation from ignorance to knowledge occurs rapidly. When confronted with a problem, individuals figure out what is known and what needs to be determined. They then think about possible solutions. Insight occurs when people suddenly “see” how to solve the problem.

Gestalt theorists disagreed with Watson and other behaviourists about the role of consciousness. In Gestalt theory, meaningful perception and insight occur only through conscious awareness. Gestalt psychologists also disputed the idea that complex phenomena can be broken into elementary parts. Behaviourists stressed associations: the whole is equal to the sum of the parts. Gestalt psychologists felt that the whole is meaningful and loses meaning when it is reduced to individual components. (In the opening scenario, “x” loses meaning unless it can be related to broader categories.) Instead, the whole is greater than the sum of its parts. Interestingly, Gestalt psychologists agreed with behaviourists in objecting to introspection, but for a different reason. Behaviourists viewed it as an attempt to study consciousness; Gestalt theorists felt it was inappropriate to modify perceptions to correspond to objective reality. People who used introspection tried to separate meaning from perception, whereas Gestalt psychologists believed that perception was meaningful.

Principles of Organization

Gestalt theory doth postulate that individuals employ principles to organise their perceptions. Amongst the most salient of these principles are figure-ground relation, proximity, similarity, common direction, simplicity, and closure (Koffka, 1922; Köhler, 1926, 1947/1959).

The principle of figure–ground relation doth postulate that any perceptual field may be subdivided into a figure against a background. Such salient features as size, shape, colour, and pitch do distinguish a figure from its background. When figure and ground are ambiguous, perceivers may alternatively organise the sensory experience one way and then another.

The principle of proximity doth state that elements within a perceptual field are viewed as belonging together according to their closeness to one another in space or time. The majority of individuals shall view the lines in Figure 5.3b as three groups of three lines each, albeit other modes of perceiving this configuration are possible. This principle of proximity is also involved in the perception of speech. Individuals hear (organise) speech as a series of words or phrases separated with pauses. When individuals hear unfamiliar speech sounds (e.g., foreign languages), they encounter difficulty in discerning pauses.

The principle of similarity doth signify that elements similar in aspects such as size or colour are perceived as belonging together. When viewing Figure c, individuals tend to perceive a group of three short lines, succeeded by a group of three long lines, and so forth. Proximity can outweigh similarity; when dissimilar stimuli are situated closer together than similar ones (Figure d), the perceptual field tends to be organised into four groups of two lines each.

The principle of common direction doth imply that elements appearing to constitute a pattern, or flow, in the same direction are perceived as a figure. The lines in Figure e are most likely to be perceived as forming a distinct pattern. The principle of common direction also applies to an alphabetic or numeric series in which one or more rules define the order of items. Thus, the next letter in the series abdeghjk is m, as determined by the rule: Commencing with the letter a and progressing through the alphabet sequentially, list two letters and omit one.

The principle of simplicity doth state that individuals organise their perceptual fields in simple, regular features, and tend to form good Gestalts comprising symmetry and regularity. This notion is captured by the German term 'Pragnanz,' which, when roughly translated, doth mean 'meaningfulness' or 'precision.' Individuals are most likely to perceive the visual patterns in Figure f as one geometrical pattern overlapping another, rather than as several irregularly shaped geometric patterns. The principle of closure doth signify that individuals fill in incomplete patterns or experiences. Notwithstanding the absent lines in the pattern depicted in Figure g, individuals tend to complete the pattern and perceive a meaningful picture.

Many of the concepts embodied within Gestalt theory are pertinent to our perceptions; however, Gestalt principles are quite general and do not address the actual mechanisms of perception. To assert that individuals perceive similar items as belonging together doth not explicate how they perceive items as similar in the first instance. Gestalt principles are illuminating, yet vague, and not explanatory. Research doth not support certain of the Gestalt predictions. Kubovy and van den Berg (2008) discovered that the joint effect of proximity and similarity was equal to the sum of their separate effects, and not greater than it, as Gestalt theory doth predict. Information processing principles, discussed next, are clearer and provide a better explanation of perception.

Environmental inputs are apprehended and assimilated through the faculties of sense: sight, audition, tactility, olfaction, and gustation. Information processing theories posit that each sense possesses its own register, which transiently retains information in the self-same form in which it is received (e.g., visual information is retained in a visual format, auditory information in an auditory format). Information persists within the sensory register for but a fleeting instant. A modicum of sensory input is transferred to the working memory (WM) for further ratiocination. Other input is expunged and supplanted by novel input. The sensory registers operate in parallel fashion, inasmuch as several senses may be engaged simultaneously and independently of one another. The two sensory memories that have been most extensively explored are the iconic (sight) and the echoic (audition) (Neisser, 1967).

In a typical experiment designed to investigate iconic memory, a researcher presents learners with rows of letters, the presentation being exceedingly brief (e.g., 50 milliseconds), and requests that they report as many as they can recall. It is commonly observed that they report only four or five letters from an array. Early work by Sperling (1960) afforded insight into iconic storage. Sperling presented learners with rows of letters, then prompted them to report letters from a particular row. Sperling estimated that, subsequent to exposure to the array, they could recall approximately nine letters. Sensory memory, therefore, could accommodate more information than was previously believed, but whilst participants were recalling letters, the vestiges of other letters rapidly faded. Sperling also ascertained that the greater the temporal separation between the termination of the presentation of the array and the commencement of recall, the poorer the recall. This finding lends credence to the notion that forgetting involves trace decay, or the loss of a stimulus from a sensory register over time.

Researchers debate whether the icon is, in reality, a memory store or a persisting image. Sakitt contended that the icon is located in the rods of the eye’s retina (Sakitt, 1976; Sakitt & Long, 1979). The active role of the icon in perception is diminished (albeit not eliminated) if the icon is a physical structure, albeit not all researchers concur with Sakitt’s position.

There exists evidence for an echoic memory, which is similar in function to iconic memory. Studies by Darwin, Turvey, and Crowder (1972), and by Moray, Bates, and Barnett (1965) yielded results comparable to Sperling’s (1960). Research participants were exposed to three or four sets of recordings simultaneously and were subsequently requested to report one. Findings demonstrated that echoic memory is capable of retaining more information than can be recalled. Analogous to iconic information, vestiges of echoic information rapidly decay following the removal of stimuli. The echoic decay is not quite as precipitous as the iconic, but periods exceeding 2 seconds between the cessation of stimulus presentation and the onset of recall result in poorer recall.

Perception, as Matlin (2009) doth aver, proceedeth via both bottom-up and top-down processing. In the bottom-up approach, the tangible properties of stimuli are apprehended by the sensory registers, whence this information is conveyed to working memory for comparison with data held within long-term memory, thereby to ascribe meanings. Environmental inputs possess manifest physical attributes. Assuming normal colour vision, one who observeth a yellow tennis ball shall recognise it as a yellow object; yet, only those conversant with tennis shall identify it as a tennis ball. The sundry meanings attributed to objects stem from the diverse knowledge that individuals have accrued.

However, perception is influenced not merely by objective attributes but also by antecedent experiences and anticipations. Top-down processing alludeth to the influence of our knowledge and beliefs upon perception (Matlin, 2009). Motivational states, too, bear import. Perception is swayed by that which we desire and hope to perceive. Oftentimes, we perceive that which we anticipate and fail to perceive that which we do not. Hath one ever fancied one heard one's name uttered, only to discover that another appellation was being proclaimed? Whilst awaiting a friend in a public locale or anticipating the collection of an order in a restaurant, one might imagine one hears one's name due to the expectation thereof. Furthermore, individuals may not perceive objects whose appearance hath altered or that occur out of context. One might fail to recognise colleagues encountered upon the beach, owing to the unexpectedness of their attire in such a setting. Top-down processing oft transpires with ambiguous stimuli or those registered but fleetingly (e.g., a stimulus espied in the 'corner of the eye').

An information processing theory of perception is template matching, which positeth that individuals store templates, or miniature likenesses of stimuli, within long-term memory. Upon encountering a stimulus, they compare it with extant templates and identify the stimulus should a match be ascertained. This notion, though appealing, is fraught with difficulties. Individuals would needs carry about myriad templates within their crania to recognise each and every entity in their environment. Such a vast repository would exceed the brain's capacity. Moreover, template theory doth poorly account for stimulus variations. Chairs, for instance, present themselves in diverse sizes, shapes, colours, and designs; hundreds of templates would be required merely to perceive a chair.

The shortcomings of templates may be ameliorated by supposing that they admit of some variation. Prototype theory doth address this. Prototypes are abstract forms encompassing the fundamental constituents of stimuli (Matlin, 2009; Rosch, 1973). These prototypes are stored within long-term memory and are compared with stimuli encountered, which are subsequently identified based upon the prototype they match or resemble in form, scent, sound, and so forth. Research lendeth support to the existence of prototypes (Franks & Bransford, 1971; Posner & Keele, 1968; Rosch, 1973).

A salient advantage of prototypes over templates resideth in that each stimulus possesseth but a single prototype, rather than countless variations; thus, identification of a stimulus should prove easier, the necessity of comparing it with sundry templates being obviated. A concern appertaining to prototypes concerneth the quantum of acceptable variability of the stimuli, or the closeness with which a stimulus must align with a prototype to be identified as an instance thereof.

A variant of the prototype model encompasseth feature analysis (Matlin, 2009). According to this perspective, one acquireth knowledge of the critical attributes of stimuli and storeth these within long-term memory as either images or verbal codes (Markman, 1999). When a stimulus entereth the sensory register, its attributes are juxtaposed with memorial representations. Should a sufficiency of attributes coincide, the stimulus is identified. In the case of a chair, the critical attributes may comprise legs, seat, and a back. Many other attributes (e.g., colour, size) are irrelevant. Any exceptions to the basic attributes must be learned (e.g., bleacher and beanbag chairs, which lack legs). Unlike prototype analysis, information stored in memory doth not constitute an abstract representation of a chair but rather includeth its critical attributes. A merit of feature analysis resideth in that each stimulus doth not possess but a single prototype, which partially addresseth the concern regarding the quantum of acceptable variability. Empirical research doth bolster feature analysis (Matlin, 2009).

Treisman (1992) proposed that perceiving an object establisheth a temporary representation within an object file, which collecteth, integrateth, and reviseth information concerning its present characteristics. The contents of the file may be stored as an object token. For newly perceived objects, we strive to match the token to a memorial representation (dictionary) of object types, which may or may not attain success. The subsequent time the object appeareth, we retrieve the object token, which specifieth its attributes and structure. The token shall facilitate perception if all of the attributes coincide, yet may impede it should many not coincide.

Irrespective of the manner in which long-term memory comparisons are effected, research lendeth support to the notion that perception is contingent upon both bottom-up and top-down processing (Anderson, 1980; Matlin, 2009; Resnick, 1985). In reading, for instance, bottom-up processing analyseth attributes and constructeth a meaningful representation to identify stimuli. Novice readers typically employ bottom-up processing when encountering letters and novel words, endeavouring to articulate them. Individuals also utilise bottom-up processing when experiencing unfamiliar stimuli (e.g., handwriting).

Reading would proceed at a snail's pace were all perception to necessitate detailed analysis of attributes. In top-down processing, individuals cultivate expectations regarding perception based upon the context. Adept readers construct a mental representation of the context whilst reading, anticipating certain words and phrases within the text (Resnick, 1985). Efficacious top-down processing is contingent upon extensive prior knowledge.