The rigid and attenuated filter models: what do they say about attention?

Two complementary explanations of how attention works.

People are constantly subjected to very complex situations in which a large number of stimuli compete for our attention. Although we may not realize it, we spend a lot of time sorting the relevant from the irrelevant, separating the wheat from the chaff.

This is mainly because our resources for processing information are very limited, so if we were to open the dam of our attention without any control, we would end up feeling how our capacity to understand what is going on around us overflows.

In order to find out how our brain works in situations as frequent as this, a series of hypotheses were postulated throughout the 20th century that would mark over the years the path to follow. Of these, the rigid and attenuated filter model was the pioneer..

In this article we will discuss the postulates of this classic model, with special emphasis on the different points that information passes through from the time it is perceived by the senses until it is persistently stored in memory.

Rigid filter model and attenuated filter model

The rigid filter model and the attenuated filter model propose a dynamic for the functioning of attention that is notable for the insertion of a filter or sifting mechanismThe rigid filter model and the attenuated filter model propose a dynamic for the functioning of attention that stands out for the insertion of a filter or screening mechanism, by means of which the complexity of the environment would be purified and relevant information would be selected. It includes elements of the multistore theory of memory, whose prior knowledge is basic for the correct understanding of these models: sensory store, short-term memory and long-term memory.

1. Sensory store

The sensory store is the first stop in the processing of information, since it is the space in which sensations from the sense organs are deposited.

The perceptual fact, through any of its different modalities (visual, acoustic, olfactory, gustatory and tactile), requires little time to be captured by the nervous system, but requires a more elaborate analysis to determine its properties. requires a somewhat more elaborate analysis to determine its physical properties and nuances..

In this store, of very large capacity but of very limited duration, an extraordinary volume of elements about the situation in which we find ourselves is sedimented, although almost all of them are diluted in a few seconds (without a deep cognitive analysis). The information would be transferred from here to the short-term memory, after being sieved by the attentional filter.which will be discussed in detail later.

Short-term memory

After the information coming from the senses has crossed the aforementioned sensory store, it would be projected to the short-term memory. At this point, an abstraction of the sensory image an abstraction of the sensory image is retained, a sort of interpretation of the objectThis interpretation is an inaccurate image, a sort of interpretation of the object on which the attention was deposited.

This interpretation is an inaccurate image, since it has been subjected to an initial has been subjected to a first process of cognitive elaboration, in which process in which some of its objective properties may have been altered.

This memory has a smaller amplitude than the sensory store, but its duration is much longer. Thus, the (now conscious) retention of this data may last for a few minutes, but will tend to dissolve if it is considered irrelevant by the receiver. Generally speaking, it is estimated that an individual (under normal circumstances) can retain up to seven simple items at this processing station, the normal range being three to eleven.

Anterograde amnesia provides reliable information on the very existence of this store, and is one of the arguments most commonly used by advocates of memory compartmentalization. This phenomenon describes the formation of new learning that lasts only a few minutes, after which it disappears without consolidation.after which they disappear without being consolidated in any case (so they would never enter the long-term storage).

Long-term memory 3.

When the information has been perceived by the sense organs, forwarded to the sensory storehouse and transferred to the short-term memory, a process of conscious analysis of its importance takes place in order to transfer it to the last station: the long-term memory. It is in this place where the declarative memories that are distant in time, and to which we resort from time to time, live.and to which we voluntarily resort when we wish to do so.

Long-term memory has an indefinite duration and can last a lifetime. Here is stored a declarative crystallization of lived events (episodic), knowledge about the world (semantic) and acquired skills (procedural), all of which are necessary for their emotional relevance and/or adaptive value. Many brain regions are involved in this process.It is therefore often affected during the evolution of dementia processes.

The filter models

Once we know the different stores into which memory is divided, and after the analysis of its process from the time the object is grasped by the senses until it is eventually stored in a lasting form, it becomes easier to understand the rigid and attenuated filter model. These theories were developed with the aim of understanding how a human being the way in which a human being deals with complex situations in which a wide variety of information in which very diverse information competes with each other to be perceived, processed and stored.

Thus, it explores the characteristics of selective attention: how we discriminate information from the environment when it is complex, in order to pick up what is relevant and articulate appropriate responses according to the context. Here we will review two pioneering hypotheses on this subject: the rigid filter (Donald Broadbent) and the attenuated filter (Anne Treisman).Both are the theoretical foundation on which later theoretical elaborations (such as the late filter model or others) would be built.

To get a better understanding of these models, the most useful approach is to give an example: imagine we are with a friend in a bar, drinking coffee, while he or she is telling us an interesting story. How do we focus our attention on his or her words if the environment is flooded with other competing sounds (such as people talking, clinking cutlery, and even cars driving near us)?

In order to explore what happens in our brains in everyday situations like this, the authors used an experimental procedure known as dichoptic listening, which consists of simultaneouslyThis consists of the simultaneous emission of two different messages through each of the auditory channels (with the help of headphones). The participant would remain seated listening to its content (numbers, words, etc.), and after the exposure would point out what he/she thought he/she had perceived.

With this simple method, the dynamics of selective attention could be explored.one of the expressions of this executive function, which consists of choosing a relevant stimulus and omitting irrelevant ones when both are presented at the same time. It is a basic skill for the development of daily life activities, together with sustained attention (or vigilance) and divided attention (efficient approach to two or more important tasks at the same time).

Although it is true that both Broadbent and Treisman agreed on the basic aspects, such as the existence of a sensory store and the process of transmission of information from short-term memory to the long-term store, they showed some discrepancies related to the concept of "filter". In both cases its existence was contemplated as a pre-screening phase for the as a preliminary screening phase of the stimulus complexity, but different views were held regarding its degree of permeability (as will be seen below).but different views were held regarding their degree of permeability (as will be seen below).

1. Rigid filter model

The use of a filter could be likened, in Broadbent's own words, to the "neck of a bottle". Although the stimulus field in which we find ourselves may be very complex, our cognitive capacities only allow a discrete percentage of it to be processed and analyzed without exceeding the resources available to us. For this purpose, the filter would act as a sieve of the environmental diversity to translate it into clear, operative and manageable terms.

This filter would be located, according to the author (although it was later called into question from Deutsch and Deutsch's late filter framework), just at the end of the sensory store and before short-term memory.. In this way, the stimuli would be processed in series, and never in parallel (which implies that the information is analyzed one at a time and never simultaneously). This filter would facilitate a selection of what is relevant and what is irrelevant, so that the former would transcend to short-term memory and the latter would be radically omitted.

According to Broadbent, the screening criterion would be the physical property of the stimulus, such as pitch or loudness of the stimulus.such as the pitch or volume of the human voice, as well as the unpredictability with which it burst into the perceptual field. Be that as it may, from these variables the individual would choose what is relevant to him, while the rest of the elements would be completely ignored without being attended to or understood.

Broadbent provided empirical evidence by means of dichotic listening, through an experimental condition that consisted of the emission of a brief list of numbers in each ear of the evaluee. For example, if the left ear heard the sequence 947 and the right ear heard 246, only one or the other would be remembered (but never information combining the two sources or the totality of the items included in the test). He concluded that each ear would function as an independent channel, with only one ear being chosen and the other completely omitted.

Attenuated filter model

The attenuated filter was proposed by Treisman, following his attempts to replicate Broadbent's findings. There is a basic difference between the proposals of these two authors, located precisely in the qualities of the filter as an element inserted within information processing.

Treisman considered that there was no absolute blocking of the unattended stimulus.The message was processed in some way even though the person tried to focus on what was relevant. The unattended messages would see their salience reduced, but they would not disappear.

Like Broadbent, he used dichotic listening to test his hypothesis. In this case, verbal-type messages (meaningful sentences) were used, but dividing the informative segments in a particular way.

For example, two logically unconnected messages (such as "I took a coat, we caught four fish") would be played in succession through the left ear, while the right ear would hear another message very similar in structure ("We went fishing because it was cold"). In such a case, the person would hear either "I took a coat because it was cold" or "We went fishing and caught four fish", showing that he or she had attended to both messages at the same time.

The explanation for this finding for Treisman was that the filter does not completely annul the unattended messageThe filter does not completely override the inattentive message, but rather it continues to be processed at some level and may come to the forefront of attention if it brings congruence to what was being perceived up to that very moment. He also demonstrated, for example, that people remembered basic aspects of the "ignored" information, even using Broadbent's own paradigm (changes in the volume of the voice, timbre, tone or sex of the speaker; as well as the reproduction of the name of the subject being evaluated).

Thus, certain conditions of the individual (such as life experience or future expectations) would be responsible for attributing perceptual relevance to the stimulus. In addition, the filter would act by weakening the less relevant messages, but these would not be completely inhibited (as suggested in the rigid filter). There would therefore be a basic processing at the semantic level. (de tipo precategorial) con el que se optimizarían las tareas de selección sin saturar el sistema cognitivo.

Referencias bibliográficas:

• Driver, J. (2001). A selective review of selective attention research from the past century. British Journal of Psychology, 92, 53-78.
• Lee, K. y Choo, H. (2011). A critical review of selective attention: An interdisciplinary perspective. Artificial Intelligence Review, 40(1), 27-50.