Complex interconnections between the different processes give information about the action and its influence. Arrows in both directions indicate that information can flow in
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both directions and also that each process can influence the other.
Inputs to the iconic storage are shown in parallel. All the information about the luminance discontinuities that
is extracted from the retina is assumed to arrive at the same time.
The two exits from iconic storage are assumed to be parallel and independent. Thus, there can be simultaneous naming of items represented in iconic storage along with a construction of their visual image representation. These are both information feature extraction processes. Haber and Hershenson contend that visual image construction always occurs but the naming may only occur if the requisite vocabulary is available. However, both of these processes are affected by the contents of short-term memory which is itself often
influenced by long-term memory so that the two processes may be affected by the extraction processes.
The interconnections between the visual and short-term memory representations indicate that both affect the other
interactively and that they both can be used to generate each other. Thus from a name, a visual image is generated even in the absence of concurrent visual stimulation.
Long-term memory is reciprocally connected.to short term memory. Thus the names of the components in the
stimulus are stored more permanently either as literal names, or more commonly as ideas or concepts. To retrieve these concepts at a later time from long-term memory they have to be recoded or encoded as words again. However these will necessarily be in the form of paraphrases of the original
coded information, since the original was not stored. Certain visual image representations are translated directly into
long-term storage as concepts or ideas. Haber and Hershenson are undecided whether an image of stimulation can be generated directly from long-term memory or whether short-term memory relay is involved. For this reason a dotted line is used for this process in the model. At all stages they hold that substages can be fitted into the overall model.
The inputs to the echoic storage are shown in parallel. All of the incoming information about the differences in air pressure that are extracted from the cochlea is assumed by them to arrive at the same time. The two exits from echoic storage are assumed to be parallel and independent although the
possibility that they are serial is not yet disproved. 3B15 ADVANTAGES OF HABER AND HERSHENSON*S INFORMATION PROCESSING MODEL
Haber and Hershenson*s model makes a distinction between retinal projection and immediate internal representation of the same, as do they that of auditory * echoic* representation. It also makes distinction at the external process, between internalized hierarchical mental organization necessary to produce alert responses and the fundamental basic responses themselves. The information processing model presented is characterized by its focus on how the information of the
luminance discontinuities contained in the retinal projection is transformed into different forms of representations or codes, visual codes, auditorily represented linguistic codes, and semantic codes. This model has the advantage of avoiding
the temptation of assuming that visual feature analysis is
the first central representation of information. The
model makes clear that several stages or processes are involved, and that in no sense can perceptual processing be considered immediate or instantaneous. Each process is
stored or rehearsed so that information processing sequences can be subdivided into stages, stores and processes - each with its own sequences, time constants and interactions.
Haber and Hershenson for this reason speak of a general model; this seems reasonable considering that any model based on
current features may be modified and distorted by future
findings. Prominence is given to visual image representation in this model It is a unique position in that previous models have not done so. What this means is that it enables the
presented model of information processing to explain various processes, not just the processing of linguistic information
(Posner and Keele 1970) but also the perception of scenes, objects and pictures.
Popper (1957) holds that,
'Experiment presupposes measurements, and measurements presuppose theories."
Bearing this in mind Haber and Hershenson1s model is employed as the central frame of reference in this investigation of the dyslexics1 abilities to process both visual and auditory material, and as such has influenced the experiments undertaken. With this in mind it must be stated here that each experiment
and findings should be able to stand on its own merits. In fact it is held that they do, irrespective of the adequacy
of the model. The model serves to integrate the separate
experiments and the findings into a workable understandable 1whole*.
It is important that one should work towards an integration of the part^ especially, as so often has happened in the
past, individual parts have been left to stand on their own with the result that no direction or trend has been observed and a general amorphous collection of parts has resulted in wanderings and justifiable criticism of this state.
3B16 RATIONALE FOR USING HABER AND HERSHENSON*S INFORMATION