In cognitive psychology, “attention” is the terminology refer to the capacity of selectively concentrating on the focused items while ignoring other things. In the post “what is working memory?”, a multi-component model of working memory was presented where the concept of “central executive controller” was formulated as a functional area in the brain for processing and manipulation of attentional selected information for short-term memory as well as long term storage afterwards. One of the major capacity of the executive controller is the attention control including the process of selection and inhibition (filter out irrelevant information).
Attention is one of the most studied area in cognitive neurobiology and cognitive psychology. The concept of attention is essential in understanding how memory works. The theories of attention form the basis on how to improve memory, prevent memory decline with age through attention control training. Patients with Adult ADHD (attention-deficit hyperactive disease) display such symptoms as
- disorganization
- extreme distractibility
- difficulty in following instructions or apparently not listening
- difficulty relaxing
- difficulty starting a task
- chronic lateness
- angry outburst
- mis-prioritize obligations (spending long time on insignificant things, but forgetting important things or tasks)
Attention can be functionally or clinically divided into several types: focused attention, selective attention, sustained attention, alternating attention and divided attention – in the order of increasing level of difficulty. The model is based on the observation in the recovering of attention processes in brain-damaged patients after coma. The clinical classification of attention or the clinical model of attention has its application in evaluating attention in patients with various pathologies corresponding to different daily difficulties and is particularly helpful for designing attention training programs and rehabilitation programs.
Focused attention is the ability to respond discretely to specific visual, auditory or tactile stimuli. Selective attention involves a selection process for focusing on a specific perception while ignoring others. Selective attention measures the ability to maintain a cognitive set in the presence of distracting or competing stimuli. The selected attention can be voluntary attentions. They can be unconscious or automatic as well (in a photo with a background, the focused image will receive attention initially). The “cocktail party effect” refers to that selective auditory attention (one only attend to one voice) with the background noises and other conversations in the room being ignored. The selective visual attention is sometime also called “attentional spotlight” where the spotlight scene will receive attention selectively which suggests visual attention can be focused on a small portion of the environment.
Sustained attention is the ability to direct and focus cognitive activity on specific stimuli for a duration of time. Sustained attention measures the vigilance capacity – the ability to maintain a consistent behavioral response during continuous and repetitive activities. A distraction can interrupt and consequently interfere in sustained attention as well. When a person has difficulty in sustained attention, they often showing difficulty in adapting to environmental demands or modify behavior.
Alternating attention (task-switching) measure the ability in shifting focus of attention between tasks having different cognitive requirements. Divided attention is the most difficult level of attention. It measures the ability to respond simultaneously to multiple tasks.
An individual’s working memory capacity is closely linked to their attentional control capacity. Attentional control allow simultaneous information being filtered and selected and gain access or entry into working memory for evaluation, manipulation and for forming behavioral decisions. The model described here explains how information across different domains (environmental stimuli: sensory or motor; stored memory, internal state) are competitively selected and transduced to the working memory through the attention system . Four processes or components are fundamental to attention: working memory, top-down sensitivity control, competitive selection, and automatic bottom-up filtering for salient stimuli (i.e. salient filter). Each process makes a distinct and essential contribution to attention. The model depicts both voluntary (endogenous attention) and involuntary attention (exogenous attention, automatic attention).
Involuntary attention or exogenous attention is the bottom-up process to capture and competitively select relevant important information (i.e salient stimuli) from external (sensory or motor) environment and filter out the irrelevant or unimportant information. Salient stimuli are those stimuli standing out from the background as in the examples of “cocktail party effect” and photo mentioned in the post. Involuntary attention involve the three processes: from automatic salience filter to the competitive selection which selects the information that gains access to the circuitry for working memory. What the salience filter does is to modulate the neural electrochemical signal strength of those competing representations of exogenous information. The competitive selection procedure determines what information will be allowed to gain access to working memory by comparing the relative signal strengths of competing representations of information.
Voluntary attention (or endogenous attention) process is a top-down goal-directed process in that the attention originates from within one’s own knowledge (stored memory or internal state). Voluntary control of attention involves the three processes from working memory to top-down sensitivity control and then going through the “competitive selection” procedure which allow new neural representations of information enter into working memory for re-processing. This loop completes the voluntary attention process. The top-down sensitivity control is the process during which signal strength representing endogenous information are modulated and increased in intensity. The responsiveness to these signals are enhanced in the brain. The endogenous signals are said to be biased because they are based on the decisions made in working memory and are derived from goal and task demand. The voluntary (endogenous) attention sometimes can be overwritten or distracted away by involuntary external stimuli if they are sufficiently salient to capture the attention.
The proposed conceptual framework for attention process suggests that attention does not consolidate information or make decisions. It is the working memory where information are further analyzed, manipulated and where decisions are made. The information subject to competitive selection are across all the domains (endogenous or exogenous). These information can be from outside environment (sensory perception, motor responses) or from internal state of the mind such as ongoing thoughts, motivations, moods as well as stored memories. Research has shown that both top-down and bottom-up control of attention requires frontal and parietal cortices. It appears that prefrontal neurons signal first during top-down voluntary attention whereas parietal neurons are activated earlier during bottom-up automatic attention.
Many factors can affect an individual’s attention control capacity including :fatigue, stress, substance use, age. Both the clinical model and conceptual model described are necessary in designing attention improvement and attention training programs such as mixed attention training, working memory training.
