Science is the attempt to answer questions through the systematic collection and analysis of objective, observable data.

Clever Hans was a horse, which had received an education and seemed to be able to answer a lot of questions, including arithmetic questions. This was, in fact, not true. The horse was able to recognize visual signals to which he responded. The story of Clever Hans shows that the result of an experiment (e.g: asking a horse what 9+10 is) can be influenced by the observers (they give unintended visual signals). This is phenomenon is known as the observer-expectancy effect.

A theory is an idea or conceptual model, that is designed to explain existing facts and make predictions about new facts that might be discovered. A hypothesis is a prediction about new facts based on the theory.

Scepticism leads to more mundane explanations instead of a highly unlikely one because scepticism leads us to test, rather than accept a bizarre theory. A theory has to be parsimonious. The simpler, more sober theories are preferred over complex theories. A theory also has to be falsifiable. Experiments should be conducted in a controlled environment because the observer (and other things) can (unintentionally) influence the outcome of the experiment. It is important that the researcher controls the conditions, to make sure that no unaccounted conditions influence the outcome of the research and to exclude alternative explanations. Besides that, researchers should beware of the observer-expectancy effects.

There are several types of research determined by:

• Research Design
  Experimental research, correlational research and descriptive research
• Research Setting
  Field and laboratory
• Data-collection method
  Self-report and observation

Experimental research is used to determine a cause-effect relationship between two variables. An experiment is a procedure in which a researcher systematically manipulates one or more independent variables and looks for changes in one or more dependent variable while keeping all other variables constant. There are two types of variables in a cause-effect relationship. An independent variable is a variable that is determined and controlled by the researcher. A dependent variable is a variable that (hopefully) is affected by the independent variable. There are two basic types of experiments. A within-subject experiment, in which the participant is exposed to each of the conditions of the independent variables and is repeatedly tested. It is a within-subject experiment if there multiple conditions of the independent variable are applied to the same subject. A between-subjects experiment, in which the participant is only tested in one condition of the independent variable and there are multiple participant groups, a group for each of the conditions of the independent variable.

A correlational study is used when you cannot conduct experimental research, such as when researching personal variables that can´t be manipulated, such as divorce. A correlational study is a study in which the researcher does not manipulate any variable, but observes or measures two or more already existing variables to find a relation between them.

It is not possible to get a cause and effect relation between two variables through a correlational study, because it is never certain that the two variables affect each other the way you might think they do. It is possible that A affects B, but also possible that B affects A, or that C affects A or B and because of this it is not possible to get a cause-effect relation by conducting correlational research. Correlation does not imply causality.

A descriptive study describes the behaviour of an individual or a set of individuals without assessing relationships between variables. A descriptive study can be very similar to a correlational study, especially when a descriptive study uses numbers (e.g: the amount of mental disorders in a community), but when the goal is to describe the situation and not to correlate two variables then it is a descriptive study.

A laboratory study is any study in which the participants are brought to a specifically designated area that has been set up to facilitate the researcher’s collection of data or control over environmental conditions. A laboratory study can be anywhere, as long as the researcher has control over the experiences the participants have at that time. A field study is any research study in which the researcher does not have control over the experiences a participant has.

A laboratory study allows the researcher to collect data under more controlled conditions than in the field, but an artificial environment can cause different behaviour than usual and the one the researcher wants to study. E.g: parent-child interactions may be different in a controlled environment than when at home.

A field experiment is possible when a researcher manipulates a variable but has no control over the other variables. (e.g: putting signs somewhere and observing what happens. The researcher has control over the variable signs, but has no control over the other variables, while he wants to research the behaviour the signs cause)

There are two broad dimensions of data-collection methods. The first one is the self-report. Self-report methods are procedures in which people are asked to rate or to describe their behaviour or mental state in some way. One form of self-report is introspection: the personal observations of one’s thoughts, perceptions and feelings. Introspection is subjective, but not unreal. Another form of self-report is when someone is asked to assessments of other people. (e.g: teacher being asked to evaluate children in terms of aggression).

Observational research includes all procedures by which observe and record the behaviour of interest rather than relying on the participant’s self-report. It is possible to test behaviour or to have a naturalistic observation in which the observer doesn’t do anything but observe. Naturalistic observation has one important disadvantage to it. People may change their behaviour if they know they are being observed. This is called the Hawthorne effect. There are two ways to minimise the Hawthorne effect. The first is called habituation. If a stimulus is repeatedly or continuously present, the participants might habituate to the presence. Another way to minimise the Hawthorne effect is hiding.

Statistics are needed to determine that the likelihood that observed patterns in data are simply the result of chance. The statistic procedures used for these purposes can be divided into two categories: descriptive statistics, which are used to summarize sets of data and inferential statistics, which help the researchers decide how confident they can be in judging that the results they observed are not due to chance.

The mean is the arithmetic average. The median is the centre score. Variability refers to the degree to which the numbers in the set differ from one another and their mean. A common measure of variability is the standard deviation. The further the most individual scores are from the mean, the greater the standard deviation is.

A correlation can be positive or negative. A positive correlation (>0) means that when variable A increases, variable B increases as well. A negative correlation (<0) means that when variable A increases, variable B decreases. If the correlation is near 0, it means that the two variables are unrelated.

Inferential statistic methods are procedures for calculating the probability that the observed effects could derive from chance alone. In a correlational study, p is the probability that a correlation coefficient as large as or larger than observed would occur by chance. If ‘p’ is <0.05 then it means that the results are statistically significant; the chance that the results occurred by chance is acceptably low.

When calculation ‘p’ the following things are needed in the calculations:

• The size of the observed effect
  The larger the size of the effect, the higher the chance that the results are statistically significant.
• The number of participants in the study
  The more participants, the less likely it is that the results occurred by chance.
• The variability of data within each group
  The less variability of data within each group, the less likely it is that the results occurred by chance

Bias refers to non-random effects caused by some factor or factors extraneous to the researchers' hypothesis. Bias can lead researchers to false conclusions, while randomness (and thus error) only increases the chance of finding statistically insignificant results. With a bias, a factor, irrelevant to the hypothesis has influenced the results. Three types of bias are the sampling bias, the measurement bias and the expectancy bias.

If the members of a particular group are systematically different from those of another group or are different than the population the researcher is interested in there is a biased sample. When conducting research, participants should be assigned to a group randomly, because the initial differences will then merely be a source of error, otherwise, there will be a bias. It is not possible to draw conclusions about a population when there is a bias in the research. A sample is biased when it is not representative of the population that researchers are trying to describe.

A measure is reliable if the measurement is:

• Replicable
  It yields about the same result every time it is used with a participant under a set of conditions, also known as replicability. Low reliability decreases the chance of finding statistical significance in research.
• Interobserver reliability
  Two observers should come to the same result when measuring something and they should be able to observe the same behaviour. The behaviour should be carefully defined ahead of time. This is done by generating an operational definition.

A measurement procedure is valid if it measures or predicts what you want it to measure or predict. A lack of validity can be a source of bias. There are several types of validity:

• Face validity
  Common sense should tell us that something is valid (it should be a reasonable way to measure what you want to measure)
• Criterion validity
  Does the measurement correlate with a related variable?

In a previous experiment with autistic children who did not have language ability, but appeared to have exactly that because a facilitator would help them type things on a keyboard. This showed the observer-expectancy bias. The observers (in this case the facilitators) expected something and unintentionally helped the autistic children write exactly that.

The observer-expectancy bias reveals itself in two ways. If an observer expects something he acts (unintentionally) different towards the participants or if the observer expects something he is quicker to see what he expects. This can be prevented by keeping the observer blind from what is expected. Participants also have expectations. This is called subject-expectancy bias. This can also be prevented by conducting double-blind research in which both the observer and the participant don’t know what is expected of them. When administering drugs to participants some should receive a placebo, to make sure that the drug doesn’t only work because of the placebo effect.

In research with humans, ethical considerations revolve around three interrelated issues:

1. A person’s right to privacy
2. The possibility of discomfort or harm
   If there is a possibility of harm there must be made sure that there is no way to test what the researchers want to test with less or no chance of harm and should be outweighed by the human benefits. Besides that, participants have to be free to quit at any time.
3. The use of deception
   Not all psychologists agree on this matter, but some psychologists believe that the use of deception is unethical and undermines the possibility of obtaining truly informed consent. Special considerations, in this case, must be given when the participants are children, have limited intellectual capabilities or have limited capabilities of their own (e.g: prisoners)

When animals are used in research the discomfort and the suffering of the animal has to be outweighed by the potential benefits of the research. Animals must be well cared for and not subjected to unnecessary deprivation or pain.

The brain contains a lot of nerve cells or neurons. The points of communication between neurons are called synapses. The brain and the spinal cord make up the central nervous system. Extensions from the central nervous system, called nerves, make up the peripheral nervous system. The difference between a neuron and a nerve is that a nerve is a bundle of neurons within the peripheral nervous system.

There are three types of neurons:

1. Sensory neurons
   These neurons carry information from sensory organs into the central nervous system.
2. Motor neurons
   These neurons carry messages out from the central nervous system to operate muscles and glands.
3. Interneurons
   These neurons exist entirely within the central nervous system and carry messages from one set of neurons to another. They collect, organize and integrate messages from various sources.

Neurons consist of the following things:

• Cell body
  This is the widest part of the neuron. It contains the cell nucleus.
• Dendrites
  These are thin, tube-like extensions that branch extensively and function to receive input for the neuron. In interneurons and motor neurons, the dendrites extend directly from the cell body. In sensory neurons, dendrites extend from one end of the axon rather than directly from the cell body.
• Axon
  This is another thin, tube-like extension from the cell body. Its function is to carry messages to other neurons or, in the case of motor neurons, to muscle cells. Each branch of an axon with a small swelling is called an axon terminal. Axon terminals are designed to release chemical transmitter molecules onto other neurons (or onto muscle cells or glandular cells in the case of motor neurons). The axons of some neurons are surrounded by a casing called a myelin sheath. This is a fatty substance produced by supportive brain cells called glial cells.

Neurons exert their influence on other neurons and muscle cells by firing off all-or-none impulses called action potentials. In motor neurons and interneurons, action potentials are triggered at the junction between the cell body and the axon. In sensory neurons, they are triggered at the dendritic end of the axon. Each action potential produced by a given neuron is the same strength as any other action potential produced neuron and the action potential retains its full strength down the axon.

A cell membrane encloses each neuron. It is porous skin that permits certain chemicals to flow into and out of the cell while blocking others. Among the various chemicals dissolved in the intracellular and extracellular fluids are some that have electrical charges. These include soluble protein molecules (A-), which have negative charges and exist only in the intracellular fluid, and sodium ions (Na+) and chloride ions (Cl-) which are more concentrated in extracellular than intercellular fluid.

The charge (-70mv relative to the outside) across the membrane is called the resting potential. The action potential is a wave of change in the electrical charge across the membrane and it moves rapidly from one end of the axon to the other. When the action potential is ‘activated’ thousands of tiny channels that permits sodium ions to pass through open up. As a result, enough sodium moves inward to cause the electrical charge across the membrane to reverse itself and become momentarily positive relative to the outside. This sudden shift constitutes the depolarization phase of the action potential. As soon as depolarization occurs, the channels that permitted sodium to pass through close, but channels that permit potassium to pass through remain open. The electrical charge is pushed back to the resting potential and even for a short while below that. This is called the repolarization phase of the action potential. To maintain the original balance of ions across the membrane, each portion of the membrane contains a chemical mechanism, referred to as the sodium-potassium pump.

The speed at which an action potential moves down an axon is affected by two things:

1. The axon’s diameter
   The larger the diameter, the less resistance there is, thus the faster the action potential moves down an axon.
2. Presence of a myelin sheath
   If there is a myelin sheath present, the action potential moves faster down the axon.

Neurons generate action potentials are rates that are influenced by all the information that is sent to them from other neurons. The junction between each axon terminal and the cell body or dendrite of the receiving neuron is referred to as a synapse. When an action potential reaches an axon terminal, it causes the terminal to release packets of a chemical substance, called a neurotransmitter. Having too little or too many neurotransmitters can cause psychological disorders. A very narrow gap, the synaptic cleft separates the axon terminal from the membrane of the cell that it influences. The membrane of the axon terminal that abuts the cleft is the presynaptic membrane and that of the cell on the other side of the cleft in the postsynaptic membrane. Within the axon terminal are hundreds of tiny globe-like vesicles.

At an excitatory synapse, the transmitter opens sodium channels in the postsynaptic membrane. The movement of the positively charged sodium ions into the cell causes a slight depolarization of the receiving neuron which tends to increase the rate of action potentials triggered in that neuron. At an inhibitory synapse, the transmitter opens either chloride channels or potassium channels. This can cause hyperpolarization.

New-born infants have more neurons in their brains than adults do. The process of creating new neurons is referred to as neurogenesis. After a while neurons enter the last stage of their development: differentiation. During this time, neurons grow in size and increase their numbers of dendrites and axons terminals as well as the number of synapses they form. Neurons and synapses die during the development of the brain. This is called selective cell death, or apoptosis. The brain first overproduces neurons and synapses, but then just as a sculptor chisels them away.

Mirror neurons reflect an individual being able to recognize when another is doing something that the self can do. Human’s mirror neurons seem to code for movement forming an action and not only for the action itself. Mirror neurons are important for imitation.

Neurons in the central nervous system are organized into nuclei and tracts. A nucleus is a cluster of cell bodies in the central nervous system and a tract is a bundle of axons that course together from one nucleus to another.

There are three categories of identifying the functions of specific brain areas:

1. Observing behavioural deficits that occur when a part of the brain is destroyed or temporarily inactivated
2. Observing behavioural effects of artificially stimulating specific parts of the brain
3. Recording changes in neural activity that occur in specific parts of the brain when an individual is engaged in a particular mental or behavioural task

Lesions in one area of the brain can also lead to changes in 0ther brain areas. Lesions are areas of damage. There are several ways of recording brain activity in humans:

There are also several ways of studying the effects of certain areas in the brain using non-human animals:

• Deliberately placing brain lesions (using surgery to destroy certain neurons)
• Stimulating specific areas of the brain (using surgery to stimulate certain neurons)
• Electrical recording of single neurons

The nervous system contains two distinct, but interacting hierarchies:

• Sensory-perceptual hierarchy
  This is involved in the data processing. It perceives sensory data about a person’s internal and external environment and it analyses those data to make decisions. The flow is from the bottom (sensory receptors) to top (perceptual centres in the brain).
• Motor-control hierarchy
  This is involved in movement. The flow is from top to bottom (brain to muscles).

The peripheral nervous system consists of the entire set of nerves, which connect the central nervous system to the body’s sensory organs, muscles and glands. Nerves are divided into two classes:

• Cranial nerves
  Nerves that project directly from the brain (12 pairs)
• Spinal nerves
  Nerves that project from the spinal cord (31 pairs)

Sensory neurons are activated at their dendritic ends by the effects of sensory stimuli (e.g: light on the eye, chemical son the tongue). They send their action potentials into the central nervous system. Somatosensation is all the sensory input that comes from the body, with the exception of specialized sensory organs of the head. The nervous system can control behaviour through motor neurons.

Motor neurons act on two broad classes of structures:

1. Skeletal muscles
   These are the muscles that are attached to bones and produce externally observable movement of the body when contracted.
2. Visceral muscles and glands
   Visceral muscles are muscles that are not connected to bones. They form walls of structures such as the heart. Glands are structures that produce secretions, such as sweat.

The peripheral nervous system consists of a skeletal portion and an autonomic portion. The skeletal muscles make up the skeletal portion and the visceral muscles and glands make up the autonomic portion. Most visceral muscles and glands receive two sets of neurons, which produce opposite effects and come from two anatomically distinct divisions of the autonomic system: sympathetic and parasympathetic. The sympathetic division responds especially to stressful stimulation helps prepare the body for fight or flight. The parasympathetic division serves regenerative, growth-promoting and energy-conserving functions.

The spinal cord has three categories of functions:

1. The spinal cord contains pathways to and from the brain
   The ascending tracts carry somatosensory information and the descending tracts carry motor control commands.
2. The spinal cord organizes simple reflex
   Simple reflexes, such as the flexion reflex do not require the brain but are operated by the spinal cord
3. The spinal cord contains pattern generators for locomotion
   The spinal cord contains networks of neurons that stimulate one another in a cyclic manner and thereby produce a burst of action potentials that wax and wane in a regular, repeating rhythm. These networks are called pattern generators.

The lower, more primitive parts of the brain are referred to as subcortical structures. The spinal cord and the brainstem are alike. They both contain ascending (sensory) and descending (motor) tracts. The brainstem also organizes some reflexes and certain species-typical behaviour patterns, but the brainstem organizes more complex and sustained reflex, such as the postural reflexes. This is a reflex that helps an animal maintain balance and vital reflexes such as breathing rate and heart rate in response to input signalling the body’s metabolic needs.

The thalamus is a relay station that connects different parts of the brain with one another. It also plays a role in the arousal of the brain as a whole. The cerebral cortex is the outer layer of the major portion of the brain. The entire folded cerebral cortex is divided into left and right hemispheres. Each hemisphere is further divided into four lobes or segments. The lobes are, from back to front, the occipital lobe, the temporal lobe, the parietal lobe and the frontal lobe.

Hormones are chemical messengers that are secreted into the blood. They are carried by the blood to all parts of the body where they act on specific target tissues. Some effects of hormones are long term or irreversible. Hormones can influence the body on an anatomical level and this can influence behaviour. There are also short term effects of hormones, such as the effects of adrenaline.

The pituitary produces hormones that stimulates the production of other hormones in other glands.

The brain consists of two hemispheres. The areas in the left are specialized for language and comparable areas in the right are specialized for nonverbal, visuospatial analysis of information. Any loss of language resulting from brain damage is called aphasia.

Photoreceptors are specialized light-detecting cells. One possible evolutionary road of the eyes is the following: photoreceptors became concentrated in groups, they began to form light detecting organs and this light-detecting organ developed until it became the eye as we know it today.

The front of the eyeball is covered by the cornea, a transparent tissue. Here the light is focussed. Behind the cornea is the iris. Inside the iris is the pupil. Behind the iris is the lens, which adds to the focusing process began by the cornea. The lens is adjustable and the cornea is not. Light forms an image of the object on the retina. The image is on the retina is upside down, but the retina’s function is to trigger patterns of activity in neurons running to the brain.

The process by which a stimulus from the environment generates electrical changes in neurons is called transduction. Transduction is the function of photoreceptor cells. There are two types of photoreceptor cells on the retina:

1. Cones
   These permit sharply focused colour vision in bright light. They are most concentrated in the fovea, the area of the retina that is in the most direct line of sight.
2. Rods
   These permit vision in dim light. They exist everywhere in the retina except the fovea.

At the place on the retina where the axons of neurons converge to form the optic nerve, there is a blind spot. We normally don’t notice this. There are two separate, but interacting visual systems within the human eye:

1. Cone vision (photopic vision)
   This is focused on high detail and colour perception. There are three types of cones, each with a different photochemical that makes it most sensitive to the light within a particular band of wavelengths.
2. Rod vision (scotopic vision)
   This is focused on seeing very dim light but lacks the capacity to distinguish colours.

The three-primaries law states that three different wavelengths of light can be used to match any colour that the eye can see if they are mixed in the appropriate proportions. The primaries can be any colour, as long as one is from the longwave end of the spectrum, one from the shortwave and one from the middle. The law of complementarity states that pairs of wavelengths can be found that, when added together, produce the visual sensation of white.

There are two theories of colour vision:

1. Trichromatic theory
   Colour vision emerges from the combined activity of three different types of receptors, each most sensitive to a different range of wavelength.
2. Opponent-Process theory
   Colour perception is mediated by neurons that can be either excited or inhibited, depending on the wavelength of the light and complementary wavelengths have opposite effects.

Most of what new-born sees is out of focus. Convergence (both eyes looking at the same object) and coordination (both eyes following a moving stimulus in a coordinated fashion) are poor at birth but develops rapidly. Synapses are formed and maintained when an organism has species-typical experience as experience-expectancy processes. As a result, functions will develop for all members of a species, given a species-typical environment.

The primary visual cortex is responsible for vision. Here, millions of neurons are involved in analysing the sensory input. In the primary visual cortex there are neurons called bar detectors, neurons called edge detectors and neurons called feature detectors.

The feature-integration theory, also called the two-stage theory states that any perceived stimulus consists of several distinct primitive sensory features (e.g: colour and the slant of its lines). The essence of this theory is that the detection and integration occur sequentially in two fundamentally different steps or stages of information processing.

1. Detection of features
   This occurs instantaneously and involves parallel processing. Parallel processing means that this step operates simultaneously on all parts of the stimulus array (our visual system picks up all the primitive features of the objects whose light rays strike our retinas at once).
2. Integration of features
   This requires more time and leads eventually to our perception of objects. This step involves serial processing, which occurs sequentially, at one spatial location at a time, rather than simultaneously (e.g: we can integrate the features of X and then an instant later the features of Y, but we can’t integrate the two sets of features simultaneously).

The Gestalt psychology stated that the whole is greater than the sum of its parts because the whole is defined by the way the parts are organized, not just by the parts themselves. They assume that we automatically perceive whole, organized patterns and objects (e.g: people perceive and recognize the chair as a whole before noticing its arms, legs and other components). The Gestalt principles of grouping are the following:

1. Proximity
   We tend to see stimulus elements that are near each other as parts of the same object and those that are separated as parts of different objects.
2. Similarity
   We tend to see stimulus elements that physically resemble each other as parts of the same objects and those that do not resemble each other as parts of different objects.
3. Closure
   We tend to see forms as completely enclosed by a border and ignore gaps in the border.
4. Good continuation
5. Common movement
   When stimulus elements move in the same direction and at the same rate, we tend to see them as part of a single object.
6. Good form
   Things that are simple, uncluttered, symmetrical, regular and predictable are more likely to be seen as a single object than as two objects.

Besides those six principles of grouping, we tend to automatically divide any visual scene in figure (the object that attracts attention) and ground (the background). This is mostly determined by circumscription. We tend to see the circumscribing form as ground and the circumscribed form as figure.

Once your visual system has hit upon a particular solution to the problem of ‘what is there’,
it may create or distort features in ways that are consistent with that inference. This is called unconscious inference, your visual system uses the sensory input from a scene to draw inferences about what is present.

Control that comes from higher up in the brain is called top-down control and they refer to control that comes more directly from the sensory input as bottom-up control. Perception always involves interplay between bottom-up and top-down control. Bottom-up processes bring in the sensory information that is actually present in the stimulus and top-down processes bring to bear the results of calculations based on that sensory information plus other information, such as that derived from previous experience and from larger context in which the stimulus appears.

The recognition-by-Components theory states that in order recognize an object, our visual system first organizes the stimulus information into a set of basic, three-dimensional components, which are called geons, and then it uses the arrangement of those components to recognize the object (e.g: an aeroplane, no matter how it is positioned relative to our eyes, always consists of the same set of geons). The theory posits that recognition of an object occurs through the following sequence:

Pick-up of sensory features -> detection of geons -> recognition of objects

People with visual agnosia can still see, but can no longer make sense of what they see. There are several types of visual agnosia:

1. Visual form agnosia
   People with this condition can see that something is present and can identify some of its elements, such as its colour and brightness, but cannot perceive its shape.
2. Visual object agnosia
   People with this condition have no problems seeing shapes, but they are unable to identify the object.

The visual areas beyond the primary area exist in two relatively distinct cortical pathways or streams, which serve different functions:

1. “What” pathway
   This stream runs into the lower portion of the temporal lobe and is specialized for identifying objects.
2. “Where-and-how” pathway
   This stream runs upward in the parietal lobe. This stream is specialized for maintaining a map of three-dimensional space and localizing objects within that space. This pathway is also crucial for the use of visual information to guide a person’s movement.

There are several cues for seeing depth. There are binocular cues and monocular cues.

Binocular cues:
There is binocular disparity, which refers to the slightly different views that the two eyes have of the same object or scene. This disparity can serve as a cue for seeing depth. The less the disparity, the greater the distance. The ability to see depth from binocular disparity is called stereopsis.

Monocular cues:
One of the monocular cues is motion parallax, which refers to the changed view one has of a scene or object when one’s head moves sideways. The smaller the change when moving your head, the greater the distance. Motion parallax depends on the geometry of true three-dimensionality. It cannot be used to depict depth in two-dimensional pictures.

There is a way to see depth in two-dimensional pictures. These cues are called pictorial cues for depth and there are several of them:

1. Occlusion
2. Relative size for familiar objects
3. Linear perspective
4. Texture gradient
5. Position relative to the horizon
6. Differential lightning of surface

The ability to see an object as unchanged in size, despite change in the image size as it moves farther away or closer, is called size constancy. Previous knowledge of the object’s usual size may contribute to size constancy.

Multisensory integration refers to the integration of information from different senses by the nervous system. When sight and sound are put in conflict with each other, vision usually wins. This is referred to as the visual dominance effect. The McGurk effect occurs when the sound is not correct according to the vision.

Multisensory integration is most apt to be perceived then the individual sensory stimuli come from the same location, arise at approximately the same time and evoke relatively weak responses when presented in isolation.

Synaesthesia is a condition in which sensory stimulation in one modality induces a sensation in a different modality.

In a model on how the memory works there are three types of memory stores:

1. Sensory memory
   There is some information stored here for a couple of seconds even when you are not paying attention to it (e.g: you can remember things you hear for approximately 4 seconds after you heard it, even if you are not paying attention to it). There is a separate sensory-memory store for each memory system.
2. Short-term (working) memory
   Information in the working memory is lost within seconds when it is no longer actively attended to. Information can enter the working memory from long-term memory and sensory memory.
3. Long-term memory
   We are not conscious of information in the long-term memory unless the information has been activated and moved into short-term memory. The long-term memory is passive.

The model specifies a set of control processes, which govern the processing of information within stores and the movement of information from one store to another. The control processes are:

1. Attention
   This is the process that controls the flow of information from the sensory memory into the working memory. Attention restricts the flow of information because the capacity of the short-term memory is small.
2. Encoding
   This is the process that controls movement from the working memory to long-term memory.
3. Retrieval
   This is the process that controls the flow of information from the long-term memory to short-term memory.

Individual mental operations can be placed on a continuum with respect to how much of one’s limited capacity each requires for its execution.

1. Effortful processes (conscious)
   These processes are available to the consciousness, interfere with the execution of other effortful processes, improve with practice and are influenced by individual differences in intelligence, motivation and education.
2. Automatic processes (unconscious)
   These processes occur without intention, are not available to the consciousness, don’t interfere with other processes, don’t improve with practice and are not influenced by individual differences in intelligence, motivation and education.

All the sensory information is briefly analysed at an unconscious level and this is called preattentive processing. The preattentive processing helps determine whether something is significant and should be paid attention to. People are able to select what they pay attention to. This is shown in a couple of ways:

• Selective listening
  This includes the cocktail party phenomenon. We only hear the conversation we want to hear and are not disturbed by other conversations. We cannot fully select what we want to hear though, as we do hear our name the moment someone says it. In the preattentive processing part, this is determined as significant.
• Selective viewing
  When we look at something we tend to ignore other visuals than the thing we are paying attention to. It is possible to miss a significant event or change because we are paying attention to something else. This is called inattentional blindness.

Auditory sensory memory is called echoic memory and visual sensory memory is called iconic memory. Sensory input can alter behaviour and conscious thought, without itself becoming conscious. This is called priming. Priming is the activation, by sensory input, of information that is already stored in the long-term memory. It is sometimes impossible to not process a stimuli (e.g: it is sometimes not possible to not read a word).

There are three general conclusions that can be drawn from brain studies concerning preattentive processing and attention:

1. Stimuli that are not attended to nevertheless activate sensory and perceptual areas of the brain
2. Attention magnifies the activity that task-relevant stimuli produce in sensory and perceptual areas of the brain, and it diminishes the activity that task-irrelevant stimuli produce.
3. Neural mechanisms in anterior (forward) portions of the cortex are responsible for control of attention.

There are people with spatial neglect, meaning that they are unable to process information in the visual field opposite to the brain hemisphere in which they have a lesion.

The working memory consists of three separate, but interacting components:

1. Phonological loop
   This is responsible for holding verbal information
2. Visuospatial sketchpad
   This is responsible for holding visual and spatial information
3. Central executive
   This is responsible for coordinating the mind’s activities and for bringing new information into working memory from the sensory and long-term stores.

The number of pronounceable items that a person can keep in mind and report back accurately after a brief delay is called the short-term memory span or the phonological loop of working memory. The phonological loop is the part of working memory that holds on to verbal information by subvocally repeating it.  The memory of the working memory is generally two items shorter than the phonological loop.

The working memory is part of executive functions, relatively basic and general-purpose information-processing mechanisms that, together, are important in planning and regulating behaviour and performing complex cognitive tasks. The executive functions consist of three related components:

1. Working memory
   Updating, monitoring and rapidly adding/deleting the contents of the working memory.
2. Switching
   Shifting flexibly between different tasks or mindsets.
3. Inhibition
   Preventing a cognitive or behavioural response or keeping unwanted information out of mind.

There are four general conclusions about executive functions:

1. Executive functions show both unity and diversity
   The executive functions are separate functions but correlate strongly with each other.
2. There is a substantial genetic component to executive functions
   The heritability of executive functions is quite high.
3. Executive functions are related to and predictive of important clinical and societal outcomes
   People who perform better on tasks of executive functions have fewer behavioural problems.
4. There is substantial developmental stability of executive-function abilities
   Although the functions improve, children who perform well on tasks with executive functions tend to perform well on these tasks as adults.

Memory refers to all the information in a person´s mind and to the mind´s capacity to store and retrieve that information. There are two types of memory:

1. Explicit memory
   This is the memory that can be brought into a person’s consciousness. It is also called declarative memory. This is memory we are aware of.
2. Implicit memory
   This refers to memory that we are not aware of. Implicit memories are much more closely tied to the context of the specific stimuli, tasks or problems to which they pertain.

There are two types of explicit memory:

1. Episodic memory
   This is memory from one’s own past experiences. Episodic memories have a personal quality.
2. Semantic memory
   This is general knowledge. There is no personal quality attached to these memories. These memories are more stable and less often forgotten.

The spreading activation model of explicit memory shows that words that are related to words seen earlier are thought of more often than words that are not related (e.g: after hearing the colour red and then asked for a flower they say rose more often than when they are not presented with the colour red first).

There are two types of implicit memory:

1. Classical conditioning effects
   These are memories that lead people to unconsciously react to certain conditioned stimuli.
2. Procedural memory
   These include motor skills, habit and unconsciously learned rules (e.g: riding a bicycle).

Any loss of long-term memory, usually resulting from some sort of physical disruption, is called amnesia. The inability to create new memories is called temporal-lobe amnesia, which is strongly correlated with damage to the hippocampus. With temporal-lobe amnesia, skill learning is not affected. People can recall nothing or barely anything from their infant years and this is called infantile amnesia.

There are two types of rehearsal:

1. Maintenance rehearsal
   This is the process by which a person holds information in working memory for a period of time
2. Encoding rehearsal
   This is the process by which a person encodes information into the long-term memory

There are several ways in which encoding is promoted:

1. Elaboration
   This is also called elaborative rehearsal and promotes encoding.
2. Organization
   This can be done through the procedure known as chunking, grouping several single items together to make them a single item. (e.g: remembering the letters b b c u v a n b c is more difficult if trying to remember it letter by letter, but easier if trying to remember it as bbc, uva and nbc).

Anterograde amnesia is the loss of capacity to form long term memories of events occurring after the injury. Retrograde amnesia Is loss of memories of events that occurred before the injury. Long-term memories are encoded in the brain in two forms: a labile, easily disrupted form and a stable, not easily disrupted form. Consolidation occurs the labile memory form is converted into the stable form. 

Sleep is important for the consolidation of memories, especially the slow-wave in the deep sleep stage.

Memories are linked to each other through associations. A stimulus or thought that becomes a particular memory is a retrieval cue for that memory. There are two principles of association:

1. Association by contiguity
   Some concepts are associated because they have occurred contiguously (e.g: plate is associated to napkin because they occur contiguously).
2. Association by similarity
   Some concepts are associated because they are similar to each other (e.g: apple is associated with pear because they are similar. They are both fruits).

Schema refers to one’s generalized mental representation, or concept, of any given class of objects, scenes or events (e.g: western people might share a schema for a living room). Schemas that involve the organization of events in time, rather than objects in space, are called scripts (e.g: a typical night out).

Leading questions can cause false memories to be created. Memories are often adapted to the schemas and scripts in the mind of a person. The word choice is also important in memories and the word choice can determine memories.

There are two possible causes of false memory construction:

1. Source confusion
   We hear many different stories of an event and may be confused about the hierarchy of the sources over time. This causes us to believe that a story about an event is closer to the truth than the first-hand experience you have yourself. Leading questions and implied meanings are important here (e.g: the roadworker said ‘crash’, so the speed must’ve been great, although you saw the cars just bump each other).
2. Social pressure
   This can lead to the construction of false memories as well.

Prospective memory is memory about things we still have to do in the future. There are two types of prospective memory:

1. Time-based prospective memory
   This involves remembering to perform a particular action when cued by a target time (e.g: answering e-mails in the evening).
2. Event-based prospective memory
   This involves remembering to perform a particular action when cued by a target event (e.g: sending someone a text message next time you see them).

There are three phases in prospective memory: an intention, the intention must be maintained and there must be a switch from the ongoing task to execute the intention.