Everyone has some concept of what attention is. Modern psychology defines it as the ability to select a portion of the information in our environment for further processing while ignoring other information. We use this ability constantly in our daily lives, for example, to read, use things and search for things. Utilizing this ability optimally helps us perform tasks at work (e.g., talking on the phone in the presence of background noise) and at play (e.g., catching a ball). Different people will use their attention in slightly different ways. However, attention shows marked differences in people with known cognitive impairments such as ADHD, dyslexia and mental illnesses such as schizophrenia. Because the ability is used so pervasively in our lives and because differences in attention are linked to cognitive impairment, it is important to clarify what exactly attention is.
Research on attention dates back to the founders of modern psychology, although it has been a topic of formal discussion since the ancient Greek philosophers. All accounts of attention suggest that it is selective — some information is brought into ‘focus’ while other information is ‘ignored’ or ‘filtered out’. But exactly how does this happen? Modern psychological and neuroscientific work on attention is broadly concerned with elaborating and investigating this process.
Any living organism is in constant interaction with its environment. Sensory activities, such as seeing and hearing involve actively orienting to relevant stimuli and away from irrelevant stimuli, rather than passively receiving incoming information. In order to focus on relevant information in our environment, then, we must first orient toward what may be of interest. Orienting can be driven by sudden changes in the visual field (e.g., the movement of a bird) or abrupt sounds in the auditory domain (e.g., the phone ringing). In general, orienting occurs to highly salient features and objects in the environment. Salience, however, is not necessarily only physical (e.g., a bright light). It can also depend on what is relevant to the observer (e.g., things that look like my keys).
Attention acts as a filter on sensory information such that some sensory information is processed to the extent that the observer can identify that information. Single-channel theory, proposed by Donald Broadbent in 1958, suggested that filtering occurs early in the processing stream and is based on physical characteristics such as location or colour (early selection). Late selection theories instead suggest that all sensory information undergoes some analysis before filtering occurs. There is currently evidence for both early- and late-selection and it is likely that each occurs in different circumstances.
The filtering aspect of attention can be seen in the famous “Gorillas in our Midst” experiment reported by Dan Simons and Christopher Chabris in 1999. In this experiment, observers watched a video display of two teams each passing a ball back and forth and were required to count the number of passes for one team. During this video sequence, a person in a gorilla suit enters the scene on one side, walks through the players and pauses in their midst while thumping their chest and proceeds to walk off on the opposite side of the screen. The gorilla is very obvious to anyone not engaged in the counting task. However, only about half of the naive observers notice the unexpected event. This study shows that, at least as far as vision is concerned, we attend to objects and events rather than spatial locations as the gorilla was present in the space that was being attended to.
The inability to detect unexpected events while attention is otherwise engaged is referred to as “inattentional blindness”. It is related to “change blindness” which refers to the finding that observers do not notice otherwise obvious changes to a scene when these changes occur during some type of visual mask, such as a blanking of the screen. A change blindness demo can be accessed here. These types of induced blindness demonstrate that attention is critically important to perceiving the content of a visual scene and that, when attention is misdirected or otherwise engaged, we can fail to notice important aspects of the scene.
Contrary to the myth of multi-tasking, it is very difficult to allocate attention simultaneously to two or more sources of information. Dividing attention like this is made easier, though, if one or both of the attentional tasks are well-practised by the observer. It is also made easier if the attentional tasks (e.g., typing and listening to the radio) are using different sensory modalities (e.g., vision and hearing).
From the studies and theories discussed above, it is clear that attention is a selective process that involves orienting to relevant parts of the environment and filtering this information. It is also clear that attention is critical to perceiving parts of the environment and that it is directed to objects/features and events, not spatial locations. As well as being selective, attention is typically thought of as integrative, in the sense that it combines different parts of sensory information into some more coherent form. A typical example of this is the combination of visual features (e.g., colour and orientation) into objects. The binding of features into objects is typically thought to require attention. Binding itself is thought to be necessary given that we perceive and recognize a world of objects and surfaces, not simply raw physical features. A theory that deals with these concepts is Anne Treisman’s Feature Integration Theory, which suggests raw visual features are combined into objects by attention acting as a binding “glue”.
Given that attention selects what information we process in more detail and integrates different aspects of that information, it is obviously a central component of human cognition. It is also related to concepts such as working memory, as what we remember can depend to some extent on what we attend to. Given that attention not only selects but also integrates, it is also possible that attention can give us insight into the human consciousness as what we are conscious of at any one moment is determined in part by our attentional system and our control over that system.
Attention is the process that selects information from our environment, filters that information and integrates different aspects of it so that we can identify, be conscious of and interact with the things in the environment that gave rise to that sensory information. It is central to human cognition and abnormal attentional patterns are observed in many cognitive impairments and mental illnesses. An understanding of attention is also critical to fields such as user interface design and human-computer interaction, as knowing what attention is and how it operates can help us better design systems that take into account the way attention operates.