Visual information from brief visual storage is transferred into short-term memory. According to Haber and Hershenson
"the sequence represents the encoding of visual information into conceptual or linguistic representations which may occur either in parallel with the construction of a visual image or in series with it."
The creation of a visual image occurs soon after the onset of visual stimulation; this visual image is correlated with the conscious awareness of the experience of perceiving. It is thought that, when the stimulus is letters, the visual form of the letters is scanned very rapidly in the iconic stage, so that they are initially coded into either letters or names. If the letters spell’a familiar word, not all of them need be scanned separately - the word as a whole is coded, the sum rather than the parts. After this process the correct name of the word would be ready for storage in the short-term memory.
Haber and Hershenson hold that the visual image is
correlated with the conscious awareness of the experience of perceiving and that this representation is integrated over time. Successive saccades introduce visual information which combine with previous ones to build up a whole or integrated* image
(picture). Formation of the same is dependent on normal
principles of perceptual organization. Duration of visual image is purely related to the correct visual fixation, the entire or 1whole* visual scene is perceived in the image which is held by rapidly changing fixations of the visual scene.
Haber and Hershenson consider that the visual image is different from the specific contents of the brief visual storage,
because, although it can be removed by a process of transfer and fade, the visual image can still persist especially if it is reinforced from short-term memory.
3B8 AUDITORY PROCESSING (ACOUSTIC CODE)
Haber and Hershenson*s model deals with both visual and auditory processing as major initial stages. Accordingly
auditory information causes a primary flow of information within their model which can be defined as a physiological process of a complex nature. However, certain basic components can be related directly to physical properties of the stimulus, e.g. amplitude or loudness.
There is a substantial amount of evidence that the short term memory representation is in the form of an acoustic code. They consider the process of naming literally as an internal function quite distinct from visual processing. The perceiver might name internally the letters presented individually or as phonemes if they are ordered, before transfer from iconic
storage to short-term memory. Again they hold that there might be a sequence of processing auditory stimuli where the acoustic
signal is held briefly in what they term ’echoic* storage while the acoustic features are processed and encoded.
The duration of information in short-term memory is very much longer than * iconic* storage*lasting minutes
if rehearsal is used. Short-term memory is not a permanent store, but it is capable of holding auditory coded information, e.g. letters and word names, and it does have a time
duration sufficient to retain information until it can be encoded and stored in long-term memory, or used in an immediate response.
Information is initially transformed in the auditory processing stage where information about the stimulus is coded in parallel processes. Simultaneous coding of a large number of auditory features into this brief auditory store is considered to be a fairly immediate process. This concept is compatible with processes and terminology used by Sperling (1963) of auditory information store, together with that of Neisser (1967).
Echoic storage is held to be related both to the
attention and kind of information being presented. Dichotic listening tasks require a refractory period of approximately 100 milli seconds for the necessary phonemic coding to
take place. Representations are lost either because of rapid decay of information, or suppression of auditory sensitivity on a fixed cyclical basis. It is considered that brief auditory storage is of such transient nature
together with a comparatively small holding store that new information erases previous inputs of information.
Like iconic memory, echoic memory has automatic persistence
mechanisms. This means in effect that if exposure duration
of the auditory field is less that 100 milli seconds the automatic persistence mechanism extends the duration of
brief auditory echoic storage to 100 milli seconds. Naturally the quality of the representation deteriorates over this
brief period and fades completely after the 100 milli seconds. For auditory perception to occur the perceiver must have approximately 100 milli seconds to respond; processing of the initial auditory stimulus takes place
during this time and information has various potentials, viz transfer to a more stable temporary store, to permanent
storage or to fade. 3B9 AUDITORY IMAGERY
From brief auditory storage information is directly transferred to short-term memory. Almost simultaneously with auditory stimulation formation of an auditory image occurs. The auditory image, according to Haber and
Hershenson, is correlated closely with the process of
conscious awareness of the perception of sound. Integration of this representation occurs over time as continuous auditory processing and gradually builds up a *picturer of the sounds, as in a word, or in a melody.