The three figures shown above exemplify the capacity of the human visual system to generate complete forms from limited sensory information.
In the bottom left we see either a complete, six-point star or a whole, white circle set within these points, the dotted lines in the middle of the image are seen as a complete winding curve, and the top right figure is perceived as a whole circle dissected by two white crosses.
All of these perceptions represent continuous forms where the actual, available sensory information is not as explicit or complete. The visual system effectively fills in the blanks to generate a more complete image than the sensory stimulus actually provides.
Reification and Form Generation
The form-generating capacity that underlies human perception was documented and highlighted by early Gestalt psychologists. The Gestaltists referred to this perceptual ability as reification, which is the conversion of an abstract concept into something concrete.
When we are only provided with part of a whole picture or an object is obscured, our visual system attempts to construct a complete impression in the mind to make the scene more meaningful and less confusing.
If the visual system made conclusions on the basis of limited sensory information, we would frequently derive the wrong impression from our environment.
For example, think of pint glasses stacked on a shelf; when we go to pick one of the glasses from the back (i.e. one obscured by those at the front) we have a complete mental image of the glass; we do not think it begins and ends at the visible portion (e.g. the rim of the glass).
Therefore, we can prepare to pick the glass up whilst accounting for the length, weight, width, and any other factor that will determine grip, pressure and the speed we lift the glass. For this reason, human perception is said to be constructive, in that a whole mental representation is constructed from less explicit sensory information.
Therefore, the visual system helps us to form a comprehensive view of our surroundings, even when there is a restricted amount of information available.
Reification is thought to arise from illusory/subjective contours, which evoke the perception of an edge without luminance or color change across that edge. Friedrich Schumann, one of the founding members of the "Society for Experimental Psychology" which was instrumental in the development of Gestalt theory, is often credited with first identifying illusory contours.
However, illusory contours were being exploited in art from the Middle Ages, so our awareness of this perceptual quality dates back long before the Society for Experimental Psychology was established in the late 19th century.
Perhaps the most common example of illusory contours in action comes from Kanizsa's Figures, which perfectly demonstrate how we perceive clearly defined shapes when the contours required to generate such a shape are not present.
We are often deprived of a complete view of our surroundings and objects within it; therefore, human perception has to fill in the blanks to help us form a complete and meaningful mental representation of each and every visual scene.
The perceptual ability to form complete representations from limited sensory information is referred to as reification, and represents one of the key principles that underpin Gestalt thinking.
The Law of Familiarity/Meaningfulness
The law of meaningfulness, also referred to as the law of familiarity, is a Gestalt principle of perceptual organisation which observes the human tendency to group visual elements when they form a meaningful or personally relevant object, item or visual scene.
Everything we do is based on the meaningfulness of information fed through our perceptual organs. We have aims and goals, which direct our behaviour, but without the right information we are lost. While the world is a complex place, we are capable of identifying individual objects and determining which elements belong to one item and discerning them from elements that belong to another.
Human perception is 'wired' to see whole objects first and foremost; what use would a mass of unconnected lines, curves, and environmental information be to us? Quite simply, none. If we are to interact accurately and safely with our environment it is essential that we are able to combine all of the elements transmitted from the eye to the brain, into meaningful, and distinct entities.
The unconscious, mental process of converting lines, curves and shapes into whole, meaningful objects represents one of the Gestalt laws of perceptual organisation, the 'Law of Familiarity/Meaningfulness'.
The words familiarity and meaningfulness are generally used interchangeably, as they both capture the perceptual bias to form mental representations that have some use or personal relevance. The principle of meaningfulness can be seen in action when we view the lines and shapes in the image above.
On their own, the component elements mean very little, but we instantly see a stickman waving as he makes his way from a house in the distance. Perceptual organisation ensures we detect regularity and form when we could just as easily see objects, people etc as a series of disconnected and meaningless component shapes, lines and curves.
The Importance of Meaningfulness/Familiarity
Through experience we form mental representations for different objects, figures, animals and any other two-dimensional or three-dimensional form. These mental representations can be applied from one situation to another, either consciously or unconsciously.
The unconscious simulation of an existing mental representation is referred to as recognition, which is a type of memory process occurring when a neural pattern associated with a previous event (e.g. seeing a dog) is excited by a new, similar instance (e.g. seeing another dog).
Over time, these neural patterns become ever more 'hard-wired', making us particularly sensitive to stimulation from new instances that might only bear slight resemblance to the existing mental representation. For example, we often see faces in inanimate objects, such as door handles and car bumpers. This usually occurs when the object(s) consists of two components at the top, such as dots, with a wider component underneath.
Examples of Meaningfulness/Familiarity
There are many examples that show human perception can be fooled into seeing meaningful representations when images or objects are ambiguous. However, from all of the principles of perceptual organisation, the law of meaningfulness is perhaps the most significant to our everyday lives.
In every situation, we are flooded with sensory information and our ability to consolidate all of this information into a coherent and consistent impression of the world is vital to our existence.
Therefore, the principle of meaningfulness allows us to place our trust in human perception and act according to the information processed in the mind, without having to constantly second guess whether we have formed accurate representations from the thousands of lines, curves, and shapes that form objects in both the physical and graphical worlds.
The Law of Symmetry
The law of symmetry is a Gestalt principle of perceptual organisation which observes the human tendency to perceive visual elements as grouped when they are part of a symmetrical arrangement.
The world may be full of complex shapes and objects, but human perception processes these complex forms in a way that leaves us with a much simpler mental representation. Human perception biases our view of complex forms and one of the primary ways this occurs is in the way we interpret and organise visual information to 'create' symmetry.
By create we mean there are many alternative interpretations or configurations possible when we view most objects, but we are biased to perceive symmetry and simplicity, even when there are a myriad of different ways to see an object.
The Gestaltists acknowledged this perceptual phenomenon and the 'Law of Symmetry' represents one of the Gestalt principles of perceptual organisation. When we look at objects, our visual organs focus our attention at the centre, which instantly influences the way in which we see the world.
Symmetry occurs where there is balance between the two halves of an object or scene from the centre. However, it is not by simply focussing on the centre of an object or scene that we experience symmetry; instead, human perception biases the way we interpret visual information, from this centre point, to ensure we extract the most simple and symmetrical form.
For example, when we look at the Audi symbol below we see four interlocking rings, as opposed a more complex series of shapes.
The Importance of Symmetry
Symmetry occurs naturally in our environment, whether it is the two sides of a snail shell, the wings of a butterfly or a human face. We unconsciously choose mates on the basis of facial symmetry, which highlights the significance of symmetry to humans and gives some suggestion why our sensory organs, those responsible for processing visual information, are attuned to detect symmetry.
Take a look at the two sets of parentheses/brackets above; of the two, which would you say is more aesthetically pleasing? The Gestalt principle of symmetry would suggest you have chosen the second set of brackets.
Now consider how this preference for symmetry might affect our viewing experience in other situations and how you might be able to use symmetry.
The Law of Continuity
The law of continuity is a Gestalt principle of perceptual organisation which identifies the human ability to determine object constancy when the whole object is not completely visible. In addition, this law identifies how we are biased to perceive interlinking or bisecting visual elements as continuous forms in a particular direction.
When one object passes over or behind another we still see two distinct forms following a particular path. For instance, when we look at the figure above, we see two distinct lines going from A to D and C to B.
There are alternative interpretations, such as A to C, C to D, and A to B, but we are biased to follow the lines according to expectation, which is based on knowledge acquired from the real-world where there is no break in nature and we learn, even when partially obscured or hidden, objects pass through all intermediate states.
This perceptual phenomenon forms the basis of the Gestalt 'Law of Continuity'; a descriptive principle of perceptual organisation that helps us appreciate how our experience of the world is heavily influenced by internal processes, and not just the information received from the world itself.
Imagine a person standing behind a lamp post with one arm held out one side and one leg held aloft the other. We can appreciate that the arm and leg belong to the same body by the law of continuity. However, there are also times where this strong perceptual bias can draw us to the wrong conclusion.
Think of a wide tree (maybe an oak), with the same arm-leg arrangement as the lamp post example. We would likely perceive this scene as one person hiding behind a tree, but in actual fact the arm and leg are from two different people. In spite of the width of the tree, the law of continuity leads us to piece together the two sides, creating our perception of one person behind the tree.
This represents an example of an optical illusion, which is essentially our perceptual system misinterpreting sensory information according to biases that are either inherent in human perception (i.e. nature) or acquired through experience (i.e. nurture).
The Law of Common Fate
The law of common fate is a Gestalt principle of perceptual organisation which identifies the human tendency to perceive visual elements moving in the same direction or in unison as grouped.
Human perception is naturally inclined to form organised groups, patterns and objects from visual information. The form-generating bias that characterises human perception is demonstrated in a number of specific ways, and they are not specific to static visual information.
For example, visual elements moving in the same direction and at the same or similar speed are perceived as belonging to or forming a group.
Picture the movement of a flock of starlings swirling in the sky; the flock may be comprised of hundreds if not thousands of individual visual elements, but their speed and direction are matched, giving the appearance of one large, cohesive group or body.
Even when two flocks of birds intersect - passing one over the other in our view - we can distinguish them by the direction common to each flock.
The Importance of Common Fate
The Gestaltists Max Wertheimer, Kurt Koffka and Wolfgang Kohler described this particular perceptual bias in their list of grouping laws; referring to it as the 'Principle of Common Fate'. The perceptual ability to trace objects according to their direction and speed is thought to represent an evolutionary need.
Our ancestors' survival was dependent on their ability distinguish potential threats (i.e. predators) from the background scene. In the absence of other visual information, such as the colour or outline of a visual element, the capacity to detect motion was hugely important, and this is still an extremely important feature of human perception, especially in the age of the car.
The Principle of Closure
There are times where we cannot see a whole object, but the human mind combines the visual information available to form a whole meaningful object; this is referred to as the law of closure, a Gestalt principle of perceptual organisation.
Such is our drive to make sense of the world, the human visual system will often interpret blank space as a whole object. The figures above serve as simple examples of the perceptual bias to piece together limited visual information with blank space, to form whole objects.
Rather than perceiving these four figures in terms of the black shapes alone, our visual system fills in the gaps between the black, visible elements, creating the impression of a triangle within a black square, a circle within a black triangle, a triangle within three black dots, and a star within sixteen black dots, respectively. Therefore, human perception 'adds' information to the visual information available to create a complete visual scene.
The Importance of Closure
The ability to piece together limited visual information to form whole mental representations of figures in our environment is an important aspect of human perception.
There are many occasions where we do not have a complete view of a single or group of visual objects; without the biasing processes that occur within our perceptual systems, visual scenes would be harder to comprehend, and extracting meaningful representations would require more time and concentration. Therefore, the biasing effects of human perception help us see the world as whole or complete.
'New' Grouping Laws
The way in which items are grouped affects the speed with which we can extract information from a display.
The graphic above shows the relative times taken to detect two neighbouring, identical shapes in various sequences of circles and squares, under different conditions. This is an example of a repetition discrimination task, developed by Palmer and Beck (2000) as a means of objectively quantifying the effect of grouping - an overarching principle within Gestalt Psychology - on perception.
The stimuli used in Palmer and Beck's (2007) repetition discrimination task consisted of different arrangements of circles and squares. Participants were required to identify neighbouring identical shapes within a sequence where only one such pair was presented in a sequence.
They had to press one key if the pair was comprised of squares or another key if it was comprised of circles. Participants' response times were then measured.
The aim of Palmer and Beck's experiment was to test the dominance of the Gestalt law of proximity, which states that we perceive items as belonging to a group when they are closer to one another. If the law of proximity is correct - and dominant - then identical shapes should elicit faster reaction times when they are closer to each other, regardless of their relationship to other non-identical shapes.
The test sequences were arranged according to these laws, with shape pairs positioned so that their proximity was at varying distances.
Three groups were established:
target pairs were to be perceived as part of the same group by use of a grouping factor like 'law of common region' identical shapes were to be perceived as belonging to two distinct groups and the control condition where no biasing factor was applied as all shapes were equally spaced and belonged to no distinct, grouped pair.
Results showed that response times were significantly slower when identical pairs were farther apart. However, the slowest response times were found in the condition where the matching pair of shapes were a smaller distance apart than in other conditions, but belonged to distinct, non-identical pairs.
Therefore, objects are not perceived as grouped primarily by their greater proximity, as non-identical pair formation was found to inhibit identical pair detection, even when the matching pair of shapes were in close proximity.
Three New Gestalt Laws
Findings from repetition discrimination tasks such as Palmer and Beck (2007) suggested the existing set of Gestalt laws did not sufficiently encompass all of the ways we group items in our environment. Stephen Palmer (1992; 1999) and Irvin Rock had previously proposed three more laws, or heuristics, to add to the established Gestalt laws of similarity and proximity, among others.
These "new" laws were the principle of common region, element connectedness and synchrony:
The Principle of Common Region
- The principle of common region refers to the tendency to perceive items as belonging together when they share a distinct area or region.
For example, pairs of dots appear to be grouped when they are surrounded by ellipses, even when they are actually closer in proximity to dots in neighbouring ellipses.
The Principle of Element Connectedness
- The principle of element connectedness acknowledges the tendency to perceive physically connected items as being grouped.
For example, dots that are joined by a straight line, giving the appearance of miniature dumbbells, are perceived as being grouped together, regardless of distance between the dots.
The Principle of Synchrony
- The principle of synchrony addresses our perception of visual events occurring in unison as representing a group. For example, flashing bulbs are perceived as grouped even when they are arranged around unlit bulbs. This principle is similar to the existing Gestalt 'Law of Common Fate', which states that similarly moving items are perceived as grouped even when spaced apart.
However, the principle of synchrony can be applied to static visual events, as light bulbs that are maintained in on or off positions, respectively, are still perceived as being grouped.
The Law of Element Connectedness
The law of element connectedness represents one of three Gestalt grouping laws added by Stephen Palmer to the existing laws. This particular law identifies the perceptual tendency to group elements when they are connected.
By connecting six of the squares with straight lines, we view these visual elements as distinct from the rest of the arrangement and grouped together. If we were to remove the straight lines, the six squares would simply appear as part of one large group.
Connecting objects in this way not only leads us to assume they are grouped, but we see them as distinct from the rest of the display. Our eye is instantly drawn to the connected items and the other squares seem to be less significant; receding into the background of our view.
Prominent psychologists Stephen Palmer, Irvin Rock and Diane Beck (1992; 1997; 2007; 2008), observed the effect of connectedness on human perception and provided substantive research to demonstrate the existence of such a perceptual bias.
They identified the existing list of Gestalt principles of perceptual organisation did not account for this particular perceptual bias, and added the 'Law of Element Connectedness' accordingly.
The Importance of Element Connectedness
The law of element connectedness is important to human perception, as it allows us to focus our attention on specific elements in our visual field and filter out other, unconnected visual objects. An inability to detect groups when items are connected would have significant implications for human perception and our capacity to draw the correct conclusions from visual information.
For example, hanging clothes on an outdoor airer would be extremely difficult if we did not instantly perceive the poles as connected by the horizontal bars. Therefore, the law of element connectedness plays an important role in our everyday interactions with the world.
The Law of Common Region
We have a strong tendency to perceive items as grouped when they are within the same clearly delineated region of space.
When visual elements are surrounded by a clear boundary, we view all items within this area as belonging to and forming a group distinct from all other surrounding elements. As you can see from the image above, just by adding a black border around three of the coloured dots we view them as distinct from the dots on the outside.
There are innumerable examples of borders being used to give the appearance of grouping, but an example common to us all is in the use of boundaries to distinguish different groups of buttons according to function on many remote controls.
The perceptual bias to see items as grouped when they share a clearly delineated body of space is referred to as the 'Law of Common Region', which was first described as a principle of perceptual organisation by Stephen Palmer, Professor of psychology at the University of California, in 1992.
The law of common region is an important feature of human perception, as it allows us to immediately detect groups without having to account for all of the visual elements contained within a scene or display individually.
The process of distinguishing items belonging to one group from all others would be a significantly more time-consuming process, and without the law of common regions we could not draw accurate, yet immediate conclusions from the visual information available to us.
Therefore, the law of common region serves a number of purposes: a simple border or boundary can speed up the process of extracting information from a scene or display, we are able to direct our attention to specific items, without having to scan all visual elements, disparate items become more meaningful, and we are less likely to confuse items that do not share a meaningful relationship.
The Law of Synchrony
Stephen Palmer added the law of synchrony to the existing Gestalt laws of grouping. This law is similar to common fate, but is distinguished on the basis that it identifies the grouping bias when visual elements appear at the same time yet they are not in motion.
When a number of events take place at the same time we are biased to perceive them as grouped or that they share the same meaning. These events do not necessarily have to be 'active'; we also tend to perceive matching, static events as grouped. Stephen Palmer, a prominent psychologist who has carried out extensive work in the field of visual perception, observed and documented this perceptual bias.
Palmer (1992) referred to this particular group-forming bias as the 'Law of Synchrony', which was added to the established list of Gestalt principles of perceptual organisation provided in the late 19th and early 20th century.
The Importance of Synchrony
The law of synchrony shares much with the law of common fate, but Palmer's grouping principle, as previously mentioned, applies to both active and static events.
Examples of synchrony biasing our perception can be seen in a number of situations, such as pupils standing up together in unison during assembly or a certain selection of bulbs lit on a control panel.
The law of synchrony allows us to instantly identify which visual elements belong to one group and distinguish them from all other unrelated elements. This can be important, especially in the modern world where computer programs use simultaneous events to distinguish items that require attention from those that can be ignored.
Therefore, the law of synchrony is perhaps of increasing importance in a world where we are ever more dependent on technologies to help us allocate our time and improve our productivity.