Attention and Perception

Abstract

This article discusses several key issues concerning the study of attention and its relation to visual perception, with an emphasis on behavioral and experiential aspects. It begins with an overview of several classical works carried out in the latter half of the 20th century, such as the development of early filter and spotlight models of attention. This is followed by a survey of subsequent research that extended or modified these results in significant ways. It covers current work on various forms of induced blindness and on the capabilities of nonattentional processes. It also includes proposals about how a "just-in-time" allocation of attention can create the impression that we see our surroundings in coherent detail everywhere, as well as how the failure of such allocation can result in various perceptual deficits. The final section examines issues that have received little consideration to date, but may be important for new lines of research in the near future. These include the prospects for a better characterization of attention, the possibility of more systematic explanations, factors that may significantly modulate attentional operation, and the possibility of several kinds of visual attention and visual experience.

Full text

In Emerging Trends in the Social and Behavioral Sciences, R.A. Scott and S.M. Kosslyn (Eds).
Thousand Oaks CA: Sage Publications.
Attention and Perception
Ronald A. Rensink
Departments of Psychology and Computer Science
University of British Columbia
Vancouver, Canada
Abstract
This article discusses several key issues concerning the study of attention and its relation
to visual perception, with an emphasis on behavioral and experiential aspects. It begins with an
overview of several classical works carried out in the latter half of the 20th century, such as the
development of early filter and spotlight models of attention. This is followed by a survey of
subsequent research that extended or modified these results in significant ways. It covers current
work on various forms of induced blindness and on the capabilities of nonattentional processes.
It also includes proposals about how a "just-in-time" allocation of attention can create the
impression that we see our surroundings in coherent detail everywhere, as well as how the failure
of such allocation can result in various perceptual deficits. The final section examines issues that
have received little consideration to date, but may be important for new lines of research in the
near future. These include the prospects for a better characterization of attention, the possibility
of more systematic explanations, factors that may significantly modulate attentional operation,
and the possibility of several kinds of visual attention and visual experience.

1. Introduction
Whenever we open our eyes, we experience an ever-changing world of colors, shapes,
and movements. This experience is so vivid and so compelling that we rarely stop to consider
whether the underlying mechanisms may have limitations. Instead, we simply have a strong
impression that we always perceive everything in front of us. Although we may need to
scrutinize something on occasion, for the most part our visual system appears to operate in an
automatic and seamless way, providing us with a complete and detailed representation of
whatever is in our field of view.
But however appealing it may be, this impression cannot be correct. Suppose someone
wants to keep track of various players in a sports game. A single player can usually be tracked
without problem. Three or four can also be tracked, although now with some effort. But as the
number increases further, simultaneous tracking of all the selected players becomes impossible.
Performance evidently depends upon a factor which enables certain kinds of perception to occur,
but which has a clear limit to its capacity. This factor is generally referred to as attention.
Work on human vision is providing increasing evidence that visual perception is the
result of several interacting processes, most of which are quite sophisticated, and many of which
have definite limits to their abilities. And rather than the outputs of these processes
accumulating in a detailed construction, much of our perception results instead from the co-
ordination of these processes. In accord with this, much of our visual experience appears to
depend on managing attention so that it is sent to the right item at the right time. As such,
attention is more than something that simply modifies or assists our perception on occasion—it is
instead a factor central to our awareness of the world around us.
2. Foundational Research
It was recognized long ago that we need to pay attention to adequately perceive our
surroundings. But it is only recently that have we obtained a better understanding of what
attention is and how it relates to perception. Building upon proposals of philosophers of the 17th
and 18th centuries, researchers in the 19th century began to map out several of its main
characteristics. For example, Hermann von Helmholtz discovered that an observer could attend

to (in the sense of recognizing) letters at locations outside of where the eyes were aimed (or
"fixated"), showing that attention is not equivalent to eye fixation. Meanwhile, William James
distinguished "sensorial" from "intellectual" attention—the former concerned with concrete
objects such as particular sports players, the latter with more abstract structures such as the
quality of the game. James also associated sensorial attention—in particular, visual attention, the
focus of this review—with clarity of perception, intensity of perception, and visual memory.
Many of these concerns became an enduring backdrop for subsequent work.
Filter Models
A more rigorous approach to understanding attention was developed during the middle
decades of the 20th century, when researchers began focusing more on its selective aspects,
and—in line with the "cognitive revolution" of that time—replaced the original emphasis on
subjective experience with an emphasis on objective models. Donald Broadbent proposed an
influential filter model, in which conscious perception was achieved via a sequence of processes
in a single perceptual pathway, with an attentional filter that gated selected aspects of a stimulus
through to later processes. An important issue was the locus of this filter: was it was early
(selection affecting the initial stages, which measured simple properties such as color and
motion) or late (selection appearing only at the highest levels, gating properties such as semantic
category)?
The work undertaken to settle this issue resulted in a great deal of information about the
ways various operations were affected by attention. However, a complete resolution of this issue
eluded researchers, and continues to do so to this day. This strongly suggests that some of the
original assumptions were incorrect: there may be, for example, more than one filter in the
pathway (not to mention more than one pathway), making questions concerning a single filter
somewhat ill-founded. To get further insights, a different approach was needed.
Spotlight Models
Despite the failure to determine whether selection was early or late, investigations into
this issue resulted in a variety of new methodologies and new frameworks. Over time, concerns
about the nature of filters receded, and were replaced by an emphasis on how attention affected
the representations themselves.

An example of such a methodology is visual search, where observers are asked to report
on a prespecified target item in a visual display. It was found, for example, that some items can
be detected immediately and without much attention (e.g., a blue dot among a set of yellow dots)
whereas others cannot (e.g., a "T" among a set of "L"s). Among the more prominent frameworks
to account for such findings was Anne Treisman's feature integration theory. This framework
modeled visual processing in terms of two stages. The first is a preattentive stage that
determines simple properties (features) such as color or motion rapidly and in parallel at each
point of the visual field, resulting in a "map" describing the spatial distribution of each feature.
The second involves a limited-capacity "spotlight" of attention that travels from item to item at a
rate of about 50 milliseconds per item, not only filtering but also binding features that correspond
to the same item (e.g., integrating the representations of the "blue" and "vertical" properties at a
location into a single representation of both). Later refinements included the guided search
model of Jeremy Wolfe and colleagues, in which items in a feature map could be selectively
inhibited or excited to improve the efficiency of search. Other variants examined issues such as
the extent to which attention might be allocated in parallel rather than in a serial fashion. All
these models had natural connections to other areas of vision science: for example, the features
found in visual search could be related in a fairly straightforward way to many of the elements
underlying texture perception.
Other approaches yielded similar results. Michael Posner and colleagues did seminal
work on cuing, showing that if a cue (such as a dot) were shown at the location of a target just
before the target appeared, detection could be sped up by several hundred milliseconds. This
speedup diminishes as the separation between target and cue is increased, something readily
accounted for by a model in which the edges of the spotlight are smooth. Meanwhile, Charles
Eriksen and colleagues showed that a spotlight mechanism could also account for the ability of
nearby items (or flankers) to interfere with detection; results also suggested that only one
spotlight operates at any time, and that it can rapidly adjust its size, "zooming" in or out as
required by the task. Owing to its ability to account for a variety of effects, therefore, the
spotlight model has become the "classical" explanation of visual attention, forming the basis of
much of our current understanding of how it operates.

Multiple-Object Tracking
A rather different approach to studying attention was developed by Zenon Pylyshyn and
colleagues, based on multiple-object tracking. Here, a set of identical items—dots on a screen,
say—is initially displayed. A subset of these is marked (e.g., some of the dots flash) and the
marked items then tracked as they randomly move around the display. The ability to track is
severely limited: under most conditions no more than 3 or 4 can be handled. The extent to which
multiple-object tracking can be explained by a spotlight mechanism remains unclear. However,
there is considerable—although not universal—belief that this tracking does involve a form of
attention, if only because of the limited capacity found.
Underlying Mechanisms
One of the more successful quantitative models of attentional filtering and binding was
the Theory of Visual Attention of Claus Bundesen, which could account for a considerable
variety of experimental data. It was also compatible with later suggestions that filtering and
binding could be implemented via neural assemblies that inhibit their neighbors when activated.
Another (possibly complementary) proposal about implementation was neural synchrony, which
posited that an attended item could be represented by the synchronized firing of a group of
neurons. More generally, many of the classical results could be explained by models based on
the dynamics of neural interactions, along with the selective routing of information from various
areas of the brain.
In parallel with this, other work focused on understanding attentional control. Michael
Posner suggested that the movement of attention involved three distinct components: (i) the
disengagement of attention from the current item being attended, (ii) the shifting of its location
(e.g., the center of the spotlight) over space, and (iii) the re-engagement of attention on a new
item. Among other things, this model successfully accounted for several perceptual problems
encountered in developmental disorders and degenerative diseases. Subsequent work placed an
increased emphasis on the extent to which control was affected by properties of the image—for
example, the extent to which the size or color of an item differed from that of its neighbors.

3. Cutting-Edge Research
The late 20th and early 21st century saw the development of several new research
directions. Some were direct continuations of classical work, and led to further refinement of
earlier results. But others involved new perspectives, and sometimes caused a reconsideration of
previous assumptions. Although these investigations have yet to result in a coherent, generally-
accepted account of attention, they have provided a better understanding of its operation,
including how it relates to other mechanisms involved in visual perception, and how its
limitations can intrude into everyday life.
Induced Blindness
Much of recent work has returned to the issue of how attention relates to conscious visual
experience—in particular, the way that an absence of attention can cause a failure to see an item
in clear view of the observer. One example is inattentional blindness, where an observer fails to
see an unexpected object or event, even when these are large and quite visible. This has been
taken to indicate that attention is needed to see an object or event. Some uncertainty exists as to
the extent of its implications at the theoretical level: does the observer fail to see all aspects of
the object, or do they still see its basic features but are blind to its structure or meaning? Either
way, inattentional blindness is increasingly recognized as being important at the practical level.
For example, many traffic accidents are likely due to a driver failing to see a pedestrian (or
another car) because their attention was focused on something else.
A variant of this is continuous flash suppression. Here, a set of random images is
continually flashed into one eye at a rate of about 10 Hz, suppressing the experience of the image
shown to the other eye. This can be sustained for several minutes. Various explanations have
been put forward for this phenomenon. The predominant hypothesis is that it occurs because
attention cannot be sent to the suppressed image, and that no other effects are responsible—i.e.,
that continuous flash suppression is a form of inattentional blindness. If so, it could be a
powerful way to study the extent to which perception can occur in the absence of conscious
visual experience.
Another phenomenon that has received a great deal of interest is change blindness. Here,
the observer fails to notice a change that occurs in an object, even if the change is large and can

easily be seen once the observer knows what it is. This phenomenon strongly suggests that
attention is needed to see change. It appears that attention engages visual short-term memory
(vSTM) to create a representation that is coherent—i.e., is integrated over some extent of space
and has continuity over some duration of time. The number of items that can be monitored
simultaneously for change is about 3 or 4, a limit similar to the capacity of vSTM. Unlike
inattentional blindness, change blindness can occur even when a change is expected. This can
lead to severe problems in everyday life, in that people can miss even a large, obvious event if
they are not attending to it the moment it occurs.
Other types of induced blindness are also of interest. One of these is the attentional
blink. This occurs when two different (prespecified) targets in a stream of rapidly-presented
stimuli appear at slightly different times; under some conditions, the first target will be seen but
not the second. This has been explained in terms of attention not being allocated to the second
item in time, possibly because the representation for the first has not yet been completed. A
related phenomenon is repetition blindness, where the observer can miss the occurrence of a
repeated item in a stream of rapidly-presented images. This is likewise believed to be due to the
failure of attention to create sufficiently quickly a representation of the repeated item.
Nonattentional Processing
The earliest stages of visual processing are generally thought to be concerned with simple
properties such as color, motion, and orientation. It was originally assumed that attention acted
directly on such properties—that they were the preattentive features uncovered in visual search.
But later work showed that search can be influenced by relatively complex localized structures
(or proto-objects) created by processes acting prior to attention. These processes can group line
segments, bind features, interpret dark regions as shadows, and perhaps even recover three-
dimensional orientation at each location in the image, essentially creating a "quick and dirty"
map of scene structure. The strength of cuing and speed of search can be similarly influenced by
the inferred structure of the background, being enhanced for items on the same surface and
diminished for items on different ones. All these results point to a considerable amount of
processing that occurs rapidly (and likely in parallel across the visual field), before attention has
had much of a chance to operate.

Recent work has also shown that observers can accurately estimate summary statistics,
such as the average size of the disks in an image, even if this image is presented for only a
hundred milliseconds or so; more sophisticated properties (e.g., Pearson correlation) can also be
estimated this way. Observers can even determine the appropriate category (or gist) of a scene
under such conditions, possibly based on these statistics. In all of these, there is no time to filter
or bind more than a few items, suggesting the existence of processes that operate prior to—or
perhaps in tandem with—visual attention.
The "intelligence" of such nonattentional processes is an open issue. Observers show
little inattentional blindness to words and pictures with a strong emotional impact (e.g., the
observer's name), indicating that some degree of recognition exists before attention is sent to the
item. In general, then, all these results imply that nonattentional processes are capable of more
than previously believed. And attention may correspondingly do less: although attention can be
used on occasion to bind visual features, for example, it may not be necessary for all aspects of
binding.
Connections with Scene Perception
Phenomena such as inattentional blindness and change blindness suggest that attention is
necessary for visual experience. And most studies concur that attention is severely limited. Why
then do we not experience such limits when viewing a scene? One possibility is that attention
can create a representation—a visual object—possessing detail and coherence, but only as long
as attention is maintained. If this can be done on a "just in time" basis—i.e., attention is sent to
the right item at the right time—the result would be a virtual representation that would appear to
higher-level processes as if it were "real", i.e., as if it contained detailed and coherent
representations everywhere. An important goal of current work is therefore to understand the
nature of the mechanisms underlying such co-ordination.
One suggestion begins with nonattentional processes providing a constantly-regenerating
array of proto-objects, which represent simple properties of the scene that are visible to the
observer. Attention can select a subset of these, "knitting" them into a coherent visual object. In
tandem with this, the statistics of the (unattended) proto-object array could determine gist; this
could help access high-level knowledge about the scene, and so guide attention to appropriate
parts of the image. In this characterization, then, scene representations are no longer long-lasting

structures built up from eye movements and attentional shifts, but are relatively temporary
structures that guide such activities. Among other things, this implies that different observers—
with different knowledge, different goals, and therefore different attentional strategies—can
literally see the same scene differently.
Connections with Perceptual Deficits
Given that attention is needed for visual experience, problems with its allocation may
explain various perceptual deficits. In unilateral neglect, for example, patients with damage to
the right posterior parietal cortex (at the top and back of the head) can fail to visually experience
whatever is in the left half of the visual field, even if this is directly in front of them. (Oddly, a
corresponding deficit does not usually result from damage to the left side.) A related condition is
extinction, where such a failure also occurs, but only when an something also exists in the right
half of the visual field. Such deficits may result from problems in shifting attention to the
relevant location (or at least, keeping it there), possibly because of damage to the parietal circuits
that control it. Interestingly, words and pictures in the neglected—and presumably unattended—
part of the visual field can still affect the observer, consistent with the proposal of intelligent
nonattentional processes.
Another condition likely related to these is simultanagnosia. Patients with this deficit
cannot see more than one coherent object (or coherent part of an object) at a time; the rest of the
scene is experienced only in a fragmented way, or not experienced at all. This has been
associated with damage to the parieto-occipital areas (at the upper part of the back of the head),
which may cause problems in allocating attention to particular objects.
4. Key Issues for Future Research
Most issues in attention research—both classical and subsequent—are still far from being
resolved. For example, what is the relation between attention and vSTM? How many
nonattentional process exist, and how intelligent is each? How exactly do the knowledge and
goals of the observer determine how attention is allocated? The answers to all of these are

necessary for a complete understanding of attention. Finding them will take many more years of
work.
Meanwhile, other issues are also beginning to emerge. Part of the reason they have
received little consideration to date is sociological: given the work still to be done on current
issues, little incentive exists to embark upon riskier ventures elsewhere. Part is methodological:
it is unclear how some of these issues could be addressed in a productive way. And part is
simple ignorance: we didn't know enough until recently to realize that some of these issues even
existed. But whatever the reason for their previous obscurity, many of these issues are becoming
increasing prominent, and may well form a critical part of future research.
Characterization
One of the most basic—and oldest—issues concerning attention concerns its nature: what
exactly is it? Over the years, attention has been characterized in various ways, such as the
quality of visual experience, or a limited “resource” that enables particular operations to be
carried out. But the greatest increase in our understanding seems to have been achieved by
focusing on the idea of selection. Could this idea be developed further, ideally in a way
consistent with most of the other characterizations that have been applied?
One possibility would be to define an attentional process as one that is contingently
selective, with that selectivity controlled via global considerations (e.g., tracking a particular
person of interest). From this perspective, “attention” is more an adjective than a noun. Any
globally-controlled process of limited capacity—such as binding visual features, or placing them
into vSTM—would be "attentional", since limited capacity implies selectivity of one form or
other. This would also be the case for any process that selectively improves the quality of visual
experience, provided only that this is done on the basis of some global consideration (e.g., not
done reflexively).
Computational Explanation
Even if attention could be described in terms of a particular function or mechanism, our
understanding of it would be incomplete: we might know how it operates, but not why. For
example, if some capacity were limited to three items, why should this be? Why not four? Why

not one? Of course, such a limit may simply be an accident of history. But it may also reflect
the influence of deeper principles.
One possible way of investigating this is to apply the computational framework of David
Marr. This framework posits that any (visual) process can be analyzed from three interlocking
perspectives: (i) function (both description and justification), (ii) mechanism (algorithm and
representation), and (iii) neural implementation. Such explanations have led to deep insights
into the nature of processes at early levels of human vision, and have helped develop their
equivalents in machine vision. A few studies, such as those of John Tsotsos, have begun
applying this approach to attention as well. Such analyses could eventually provide considerable
insights into its nature and the exact role it plays in perception.
Modulatory Factors
Attention is often assumed to be governed entirely by the demands of the task and the
knowledge of the observer. However, evidence is emerging that other factors also play an
important role:
1. Stress. Stress can cause tunneling, where the observer loses awareness of anything
beyond the center of their visual field. It can also speed up visual search for simple
features (e.g., a particular orientation, such as "vertical"), although apparently not for
their combination (e.g., "blue" and "vertical"). Such effects suggest that stress causes
attention to improve its selectivity by reducing the range of the properties allowed
through. However, it may be that such improvement is obtained at the cost of a slower
switching of the underlying mechanisms.
2. Aging. Another important perspective is how attention changes over lifespan. Different
aspects of attention appear to be differently affected: filtering and binding appear to be
largely unaffected, while top-down control (e.g., disregard of irrelevant stimuli, switching
speed) deteriorates noticeably with age. More investigation would be of great practical
importance, and could provide new perspectives on underlying mechanisms.
3. Cultural / Visual Environment. Recent work suggests that observers from Western
countries (e.g., the United States) generally attend to individual objects in a scene,
whereas observers from East Asian countries (e.g., Japan) generally attend to the scene as

a whole. Western observers show a search asymmetry: they can detect a long line among
short lines more quickly than vice versa. Meanwhile, East Asian observers are equally
slow for both. Preliminary work suggests that some of these differences disappear when
significant time is spent in the other culture. If these results hold, they would indicate a
strong effect of culture—or at least, visual environment—on the way attention is used.
Interesting issues would then arise as to which (visual) characteristics are relevant, and
why.
4. Mental Set. Attentional control—including the speed of visual search—can be
influenced by the nature of the task and explicit instruction to the observer. Such results
suggest that an observer may have available several processing modes, each
corresponding to a particular "mental set". (Some of these may account for the cultural
differences mentioned above.) If so, interesting questions arise as to the nature of these
modes, and the conditions that trigger them.
Kinds of Attention
Another important issue is whether there exists one kind of attention or several.
Occasional conflicts have occurred in claims regarding the speed, sensitivity, and even function
of attention. Some of these issues could be resolved if there existed more than one kind of
attention. The existence of different kinds of attention would also create new challenges, such as
determining the taxonomy that would best describe these kinds, and establishing the various
ways in which a process could be "preattentive" or "nonattentional".
Based on function, speed, and structures operated upon, several groupings of attentional
processes can be delineated. An important question is the extent to which these groupings
correspond to distinct aspects—or even kinds—of attention (or perhaps more precisely,
attentional processing):
1. Attentional Sampling. This is the selective pickup of information by the eye. The eye
has high acuity and color perception only in the few degrees around the point of fixation.
It must therefore—together with the head and body—move around to pick up the right
information from the environment. Sampling has traditionally been referred to as overt

attention. It has long been known to differ from operations carried out internally, which
are often collectively referred to as covert attention.
2. Attentional Filtering (Gating). Irrelevant information can degrade performance, and
must be removed as soon as possible. Ways of doing so include spatial filtering
(selection only from a particular region of space) and feature filtering (selection of items
containing a particular feature); these are largely the focus of classical approaches.
Selection can be diffuse (over a wide range) or focused (over a restricted range). It
appears that the mechanisms involved can be switched quickly (typically, within 50
milliseconds) and operate on the basis of simple properties, such as color, motion, or
spatial position.
3. Attentional Binding. This is the selective linking of properties so as to capture the
structure of the world at any given moment. This can be done in various ways, such as
feature binding (e.g., linking the color and orientation of an item) and position binding
(e.g., linking an item to a precise position in space). Binding differs from filtering, being
concerned not with access, but construction. The mechanisms involved also appear to
differ, being slower (completing within about 150 milliseconds) and involving organized
structures rather than simple properties.
4. Attentional Holding. When a physical object changes over time (e.g., a bird takes
flight), it is useful to perceive an underlying structure that remains the same. The
associated representation must be stabilized (or "held") across time, likely via vSTM;
such holding therefore differs from binding. The mechanisms involved also appear to
differ, being even slower (completing within about 300 milliseconds) and operating on no
more than 3-4 items at a time.
5. Attentional Individuating. It is often useful to perceive not just an object, but a
particular object (e.g., when determining if one item is to the left of another). Such
individuating (or "indexing") may also be the basis of tracking. The mechanisms
involved can act quickly (about 50 milliseconds per item) and involve up to 7-8 structures
at a time.

Kinds of Visual Experience
A parallel set of concerns involves the nature of conscious visual experience. As in the
case of attention, it has been widely assumed there exists only one kind of visual experience.
But just as color and motion are distinct aspects—or even kinds—of experience concerned with
distinct physical properties of the world, so might there be other kinds of experience concerned
with distinct structural properties:
1. Fragmented experience. This is the experience of simple features with little structure
and poor localization; in some ways, it is what is experienced when viewing an
Impressionist painting. It can be encountered in brief displays, where the experience is
one of a fleeting array of simple colors and poorly-articulated shapes. This has
sometimes been referred to as "background consciousness"—the experience of the
background when attention (binding) is focused on foreground objects.
2. Assembled experience. This is the experience of unstructured properties (fragmented
experience) along with a degree of superimposed static structure. It can be encountered
in displays presented for about 150 milliseconds, the time needed for binding; it is
essentially what is experienced under stroboscopic conditions. Although no new sensory
(physical) properties are present, new kinds of structure are (e.g., the linking of line
segments into particular shapes). Among other things, this distinction allows two kinds
of inattentional blindness to be distinguished: Type 1, the absence of fragmented
experience (i.e., the absence of sensory qualities, perhaps caused by an absence of
attentional gating), and Type 2, the absence of assembled experience, with simple sensory
qualities still present but no higher-level structure (perhaps caused by an absence of
attentional binding).
3. Coherent experience. This is the "standard" experience encountered when giving
complete attention to a physical object: not only is the static structure of assembled
experience present, but also movement—or more generally, change—along with the
impression of an underlying substrate that persists over time. The absence of coherent
experience (change blindness) might be regarded as Type 3 inattentional blindness,
caused by an absence of attentional holding.

4. Sensing. Observers in change detection experiments occasionally report that they
“sense” or “feel” a change without having any visual experience of it. The status of this
"sensing" is controversial. It is sometimes considered simply a "weakened" form of
seeing (i.e., coherent experience). However, it differs qualitatively from the other kinds
of visual experience, and appears to involve different mechanisms as well.
An important challenge for future work is to determine the extent to which these really are
distinct kinds of visual experience, and how they may relate to various kinds of attention.
Important issues also exist concerning what might be called "dark structure": structure that is
never experienced, yet still affects visual perception.
5. Conclusion
The nature of attention and its relation to perception have long been issues cloaked in
mystery, involving matters that are highly subjective and poorly defined. But a great deal of
progress has been made, particularly over the past century. A considerable amount of
understanding now exists as to how attention operates, and the role it plays in our conscious
experience. And, importantly, this understanding has suggested new questions, concerning
issues that researchers of earlier times had not even imagined. Investigating these issues will no
doubt require much time and effort. But the results are likely to shed interesting new light on the
way we experience our world.

Further Reading
Bundesen, C. & Habekost, T. (2008). Principles of Visual Attention: Linking Mind and Brain.
Oxford: University Press.
Itti, L., Rees, G., & Tsotsos, J.K. (2005). The Neurobiology of Attention. San Diego: Academic
Press.
Mack, A., & Rock, I. (1998). Inattentional Blindness. Cambridge MA: MIT Press.
Pashler, H.E. (1999). The Psychology of Attention. Cambridge MA: MIT Press.
Rensink, R.A. (2013). Perception and attention. In D. Reisberg (Ed). Oxford Handbook of
Cognitive Psychology. Oxford: University Press. pp. 97-116.
Simons, D.J. (Ed.). (2000). Change Blindness and Visual Memory. New York: Psychology
Press.
Styles, E.A. (2006). The Psychology of Attention (2nd ed.). New York: Psychology Press.
Tsotsos, J.K. (2011). A Computational Perspective on Visual Attention. Cambridge MA: MIT
Press.
Wolfe J.M. (2000). Visual attention. In K.K. De Valois (Ed), Seeing (2nd ed). San Diego:
Academic Press. pp. 335-386.
Wright, R.D. (Ed.). (1998). Visual Attention. Oxford: University Press.

Biography
Ronald A. Rensink is an Associate Professor in the departments of Computer Science and
Psychology at the University of British Columbia (UBC) in Vancouver, Canada. His interests
include human vision (particularly visual attention and consciousness), computer vision, visual
design, and the perceptual mechanisms used in visual analysis. He obtained a PhD in Computer
Science from UBC in 1992, followed by a postdoctoral fellowship for two years in the Psychology
department at Harvard University. This was followed by six years as a research scientist at
Cambridge Basic Research, a laboratory sponsored by The Nissan Motor Company. He returned
to UBC in 2000. He is currently part of the UBC Cognitive Systems Program, an interdisciplinary
program that combines Computer Science, Linguistics, Philosophy, and Psychology. Among
other things, he is a co-founder of the Vancouver Institute for Visual Analytics (VIVA), an
institute dedicated to facilitating the development of systems that can combine human and
machine intelligence in optimal ways.
Webpage:
http://www.psych.ubc.ca/~rensink
http://www.cs.ubc.ca/~rensink