Models of Attention

Models of Attention

Early selection theories

Broadbent’s model of selective attention or Filter theory

The theories described here belong to the group of filter and bottleneck theories. A filter blocks some of the information going through and thereby selects only a part of the total of information to pass through to the next stage. A bottleneck slows down information passing through. The models differ in two ways. First, do they have a distinct “filter” for incoming information? Second, if they do, where in the processing of information does the filter occur (early or late)?

Broadbent’s Model

According to one of the earliest theories of attention, we filter information right after we notice it at the sensory level. Multiple channels of sensory input reach an attentional filter. Those channels can be distinguished by their characteristics like loudness, pitch, or accent.

The filter permits only one channel of sensory information to proceed and reach the processes of perception. We thereby assign meaning to our sensations. Other stimuli will be filtered out at the sensory level and may never reach the level of perception.

Broadbent’s theory was supported by Colin Cherry’s findings that sensory information sometimes may be noticed by an unattended ear if it does not have to be processed elaborately (e.g., you may notice that the voice in your unattended ear switches to a tone). But information requiring higher perceptual processes is not noticed if not attended to (e.g., you would likely not notice that the language in your unattended ear switches from English to German).

Selective Filter Model

The evidence began to suggest that Broadbent’s model must be wrong. Moray found that even when participants ignore most other high-level (e.g., semantic) aspects of an unattended message, they frequently still recognize their names in an unattended ear. He suggested that the reason for this effect is that messages that are of high importance to a person may break through the filter of selective attention. But other messages may not. To modify Broadbent’s metaphor, according to Moray, the selective filter blocks out most information at the sensory level. But some personally important messages are so powerful that they burst through the filtering mechanism.

Attenuation Model

To explore why some unattended messages pass through the filter, Anne Treisman conducted some experiments. She had participants shadowing coherent messages, so they must have been somehow processing the content of the unattended message.

Moray’s modification of Broadbent’s filtering mechanism was clearly not sufficient to explain Treisman’s findings. Her findings suggested that at least some information about unattended signals is being analyzed. Treisman proposed a theory of selective attention that involves a later filtering mechanism (Figure 4.9). Instead of blocking stimuli out, the filter merely weakens (attenuates) the strength of stimuli other than the target stimulus. So when the stimuli reach us, we analyze them at a low level for target properties, we pass the signal on to the next stage; if they do not possess those target properties, we pass on a weakened version of the stimulus. In a next step, we perceptually analyze the meaning of the stimuli and their relevance to us, so that even a message from the unattended ear that is supposedly irrelevant can come into consciousness and influence our subsequent actions if it has some meaning for us.

Late-Filter Model

Deutsch and Deutsch developed a model in which the location of the filter is even later. They suggested that stimuli are filtered out only after they have been analyzed for both their physical properties and their meaning. This later filtering would allow people to recognize information entering the unattended ear.

Note that proponents of both the early and the late-filtering mechanisms propose that there is an attentional bottleneck through which only a single source of information can pass. The two models differ only in terms of where they hypothesize the bottleneck to be positioned.

Late selection theories

Neisser’s synthesis model

A Synthesis of Early-Filter and Late-Filter Models

Both early and late selection theories have data to support attention models. In 1967, Ulric Neisser synthesized the early-filter and the late-filter models and proposed that there are two processes governing attention:

• Preattentive processes: These automatic processes are rapid and occur in parallel.

They can be used to notice only physical sensory characteristics of the unattended message. But they do not discern meaning or relationships.

• Attentive, controlled processes: These processes occur later. They are executed serially and consume time and attentional resources, such as working memory.

They also can be used to observe relationships among features. They serve to synthesize fragments into a mental representation of an object.

A two-step model could account for Cherry’s, Moray’s, and Treisman’s data. The model also nicely incorporates aspects of Treisman’s signal-attenuation theory and of her subsequent feature-integration theory.

Feature‐Integration Theory

Treisman (1980) started this theory with simple foundations, however the current form of the theory is complex and complicated. Three different aspects

of the theory are considered.

a. Basic elements of the theory

b. Research on the theory

c. Current status of the theory

Basic Elements

1. Treisman suggests that we look at a scene, two kinds of attentional processes take place.

2. In the beginning, all parts of the scene are processed at the same time called distributed attention (divided attention). Such attention is

automatic, effortless, fast and is carried out as a parallel process.

3. The second kind is focused attention, which involves consciously driven, effortful, slow processing carried out as a serial process.

Research on Theory

1. Treisman suggests that we look at a scene, two kinds of attentional processes take place.

2. In the beginning, all parts of the scene are processed at the same time called distributed attention (divided attention). Such attention is

automatic, effortless, fast and is carried out as a parallel process.

3. The second kind is focused attention, which involves consciously driven, effortful, slow processing carried out as a serial process.

Illusory Conjunctions

1. Later research showed that we make in search when two features in two objects are confused. Presented with blue N and green T, results in blue T.

2. For our auditory sense we make similar errors.  Given “dax” and “kay” as nonsense syllables participants respond by the word “day”.

3. Such errors (illusory conjunctions) are cussed by object proximity or if there is distraction in attention to begin with.

4. Presence of illusory conjunctions suggests that features are processed separately and then put together later in our minds (binding problem).

5. Lack of focused attention leads to illusory conjunctions and thus form the basis of integrated perception of features or binding problem.

Current Status of the Theory

1. Over 25 years Feature‐integration theory has gone through major revisions and has become a complex theory.

2. Errors based on illusory conjunctions can be reduced with practice (Coren et al., 2004; Treisman, 1992)

3. For some tasks distributed and focused attentional processes loose distinction.

4. Theory awaits new neurophysiological insights. However serves as a strong framework to explain visual attention.