model pemerhatian berpilih treisman

Treisman's Attenuation Model

Selective attention requires that stimuli are filtered so that attention is directed. Broadbent's model suggests that the selection of material to attend to (that is, the filtering) is made early, before semantic analysis.
Treisman's (1964) model retains this early filter which works on physical features of the message only. The crucial difference is that Treisman's filter ATTENUATES rather than eliminates the unattended material.  Attenuation is like turning down the volume so that if you have 4 sources of sound in one room (TV, radio, people talking, baby crying) you can turn down or attenuate 3 in order to attend to the fourth.

The result is almost the same as turning them off, the unattended material appears lost. But, if a nonattended channel includes your name, for example, there is a chance you will hear it because the material is still there.
Treisman's Attenuation


Treisman agreed with Broadbent that there was a bottleneck, but disagreed with the location. Treisman carried out experiments using the speech shadowing method.  Typically, in this method participants are asked to simultaneously repeat aloud speech played into one ear (called the attended ear) whilst another message is spoken to the other ear.

In one shadowing experiment, identical messages were presented to two ears but with a slight delay between them. If this delay was too long, then participants did not notice that the same material was played to both ears.  When the unattended message was ahead of the shadowed message by up to 2 seconds, participants noticed the similarity.  If it is assumed the unattended material is held in a temporary buffer store, then these results would indicate that the duration of material held in sensory buffer store is about 2 seconds.

In an experiment with bilingual participants, Treisman presented the attended message in English and the unattended message in a French translation.  When the French version lagged only slightly behind the English version, participants could report that both messages had the same meaning.  Clearly, then, the unattended message was being processed for meaning and Broadbent's Filter Model, where the filter extracted on the basis of physical characteristics only, could not explain these findings.  The evidence suggests that Broadbent's Filter Model is not adequate, it does not allow for meaning being taken into account.

Treisman's ATTENUATION THEORY, in which the unattended message is processed less thoroughly than the attended one, suggests processing of the unattended message is attenuated or reduced to a greater or lesser extent depending on the demands on the limited capacity processing system.

Treisman suggested messages are processed in a systematic way, beginning with analysis of physical characteristics, syllabic pattern, and individual words.  After that, grammatical structure and meaning are processed. It will often happen that there is insufficient processing capacity to permit a full analysis of unattended stimuli. In that case, later analyses will be omitted.  This theory neatly predicts that it will usually be the physical characteristics of unattended inputs which are remembered rather than their meaning.
 
To be analysed, items have to reach a certain threshold of intensity All the attended/selected material will reach this threshold but only some of the attenuated items.  Some items will retain a permanently reduced threshold, for example your own name or words/phrases like 'help' and 'fire'.  Other items will have a reduced threshold at a particular moment if they have some relevance to the main attended message.

Evaluation of Treisman's Attenuation Model

1. Treisman's Model overcomes some of the problems associated with Broadbent's Filter Model, e.g. the Attenuation Model can account for the 'Cocktail Party Syndrome'.
2. Treisman's model does not explain how exactly semantic analysis works.
3. The nature of the attenuation process has never been precisely specified.
4. A problem with all dichotic listening experiments is that you can never be sure that the participants have not actually switched attention to the so called unattended channel.