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MRCPsych : Perception, Memory and Attention. Dr Alexandra Hooper Clinical Psychologist CAMHS. Perception. Perception- Gestalt Theory. Information received through the sensory organs is vast and constantly changing - therefore we must establish some form of order.
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MRCPsych: Perception, Memory and Attention Dr Alexandra Hooper Clinical Psychologist CAMHS
Perception- Gestalt Theory • Information received through the sensory organs is vast and constantly changing - therefore we must establish some form of order. • We have a preference for whole objects “the whole is greater than the sum of the parts” • Proposes the brain organises itself in regular and predicable ways – largely innate • Perceptual grouping egsquareness • Look for organised wholes in figure ground differentiation
Figure-Ground Differentiation • Rubin – visual separation of an object from its setting • Visual field can be divided into two basic parts; figure and ground. • Only able to focus on one at a time – the figure and ground cant be seen simultaneously as ground becomes figure when the focus is shifted
Perceptual Organisation • Law of Closure – we fill in the blanks in order to complete a regular figure / object:
Law of Similarity – Organised together if they look similar. This might depend of relationships of form, colour, size or brightness
Law of Proximity – the closer two figures are to each other the more we will group them together perceptually:
Law of Symmetry – Symmetrical images are perceived collectively:
Law of Continuity – we group with as few interruptions as possible:
Law of Common Fate – elements seen moving together are perceived as belonging together.
Object Constancy The ability to perceive an object as unchanging and constant under changing conditions • Size / depth constancy: Object is same size regardless of distance (as object recedes it is not seen as decreasing in size) Appearing in infants only a couple of weeks old, although not believed to be innate.
Shape Constancy: we perceive the shape of the object more or less independently from the angle from which it is viewed • Brightness constancy: enable us to view object as being the same apparent lightness and colour despite change. Objects appear the same colour at sunset even though proportionally there is far more red light in the sun-light.
Example of object constancy: http://www.youtube.com/watch?v=-RyFPfsxT18&feature=relmfu
Bottom up theory of perception • GIBSON • Perception is a sensation that occurs primarily within the CNS with little further processing • Directly determined by the information presented to the sensory organs. • Primary function of perception is to facilitate interactions between individual and environment. • Optic flow: the point which we appear motionless while other parts of the optic field move more rapidly (pilot take off/land)
Textual gradients: This gives information about depth. Objects which are closer can be seen in greater detail than objects further away • Affordances: Objects afford (offer) us information about their function and the opportunity to use them in some way. How we use them depends on a combination of information from the optic array, the physical surroundings and the person’s psychological and physiological state.
Top down theory of perception • GREGORY • Perception involves analysis of sensory information. We only attend to some information and then fill in the gaps according to what we know and expect to see according to our prior knowledge of the world • Actively construct our own perception • Problem solving – hypothesis testing when sensory input is unusual.
Illusions • Misrepresentations of external stimuli • Gregory took illusions as evidence of his theory
Perceptual Set Theory • Gregory and Allport • Directly relevant to Gregorys view that perception is an active process involving selection, inference and interpretation • We select what we perceive and then interpret it according to different factors • context • previous instructions • personality • previous experience • cultural factors • perceptual accentuation (like)/ defence (dislike)
Factors which influence or induce set include: • Motivation • Emotion • Values • Beliefs • Cognitive styles • E.G. Hungry people more likely to see pictures which are neutral or ambiguous as food. • Anxious people respond more quickly to the presentation of threatening material. (clinical implications)
Human perception • Babies can perceive light in the womb • Colour seen by 4/12 • Depth perception is innate and develops early but avoidance takes 4-6/12
Perceptual experiments • Blind since birth – receives successful corneal transplant • Certain aspects of visual perception were innate such as detection (scanning of a shape such as a triangle, however figural identity (recognising and naming shape as a triangle) is learnt through experience. • Patient S.B.
Perception Abnormalities • Relevant clinically • E.g. Depth perception may be abnormal in those with schizophrenia • Illusions are real objects or stimuli that have been distorted (e.g. dark shadow in a bush) • Hallucinations are perceptions which are not related to any external stimuli and are internally generated • But are perceived as actually external • Can be found in schizophrenia, personality disorder and epilepsy • Also in Charles Bonnet Syndrome in which patients with visual loss and a lack of normal nerve impulses reaching the brain, have complex visual hallucinations – when the brain attempts to interpret the signals it may generate spontaneous nerve activity which causes the hallucinations.
Attention http://www.youtube.com/watch?v=vJG698U2Mvo http://www.youtube.com/watch?v=lHd_L7dg3U4
Information Processing and Attention • Information Processing • Information is any input – tactile, visual, auditory etc. • Processing refers to any action or function carried out on this information. • E.g. visual information is processed to provide derivative information about depth, contour etc. • Information processing is mostly automatic
James (1890) definition.. • “It is the taking possession by the mind, in clear and vivid form, of one out of what seems several simultaneously possible objects or trains of thought. Focalisation, concentration of consciousness are of its essence. It implies withdrawal from some things in order to deal effectively with others.”
What is Attention? • To cope with the vast amount of information, we must selectively attend to only some information and somehow ‘tune out’ the rest. • Focussed attention: Attending solely to one source of info whilst being distracted by another (e.g. cocktail party phenomenon – listening to one of two voices in a hubbub of others) • Divided attention: Attending to two or more sources of attention simultaneously (E.g. driving and answering your phone)
Dual Task Performance • Eyesnck & Keane (1995) identified 3 factors which affect our ability to perform two tasks at one: • Difficulty - Generally the more difficult the task the less successful dual task performance is (subjective) • Practice – Practice improves dual task performance. This could be because people develop new strategies for performing each task minimising interference between them • Similarity – When people are asked to attend to two different stimulus modalities it is more successful
Theories of Attention • Broadbent’s (1958) Filter Model
Attention and Mental Health • Schizophrenia: Attention difficulties due to the lack of early filtering and a consequent overload at the late stage of processing • Attention focus: anxious subjects search for threat-congruent material, detecting it more quickly than controls – which is maintenance factor in anxiety disorders
Blakemore (1988) • “Without the capacity to remember and to learn it is difficult to imagine what life would be like, whether it could be called living at all. Without memory, we would be servants of the moment, with nothing but our innate reflexes to help us deal with the world. There would be no language, no art, no science, no culture. Civilisation itself is the distillation of human memory.”
Memory • Refers to the way in which we record the past and utilise it for later so it can affect the present: • The SENSORY STORE: very brief store for the first level of observation including visual iconic (up to 0.5 second) and auditory echoic memory (up to 2 seconds) • The SHORT TERM MEMORY: Suggested to be 0-18s long where information that is processed is either sent to the long term memory or lost. The short term memory is proposed to have a capacity of 7 (+/- 2) • The LONG TERM MEMORY: ‘indefinite’ storage consisting of episodic and semantic memories.
Types of Long Term Memory • DECLARATIVE (EXPLICIT) MEMORY: Refers to memories which can be consciously recalled such as facts and knowledge: • Semantic Memory: Stores factual information – memory of meanings, understandings and other concept based knowledge unrelated to specific experiences. (E.g. Are wrenches pets or tools? – you can answer without remembering any specific event in which you learnt that wrenches are tools. • Episodic Memory: Stores specific personal experiences – Memory of autobiographical events that can be explicitly stated. Events that are recorded in episodic memory may trigger episodic learning (e.g. bitten by a dog results in fear of dogs is episodic learning) Conscious, intentional recollections of previous experiences and information – use explicit memory throughout the day e.g. remembering time of appointment or recollecting an event from years ago.
2. PROCEDURAL (IMPLICIT) MEMORY: The memory of how to do things. Guides the processes we perform without the need for conscious control or attention. Automatically retrieved and used for the execution of the integrated involved in both cognitive and motor skills (e.g. tying your shoes or reading) Implicit memory in which previous experiences aid in the performance of a task without conscious awareness of these previous experiences.
Encoding, Storage and Retrieval • Encoding: Refers to the registration of the information. The information processing system codes the new/incoming information – can be affected by the ‘serial position effect’ (primary and recency effects) which means information presented first is remembered best and information presented last is remembered second best. • Coding affected by characteristics of the individual – an unknown language will be coded as sounds (phonemically), while one familiar with the language will code it as language – extracting meaning from the sounds.
Storage: Refers to the holding of information • Storage is unlimited and permanent where any ‘memory loss’ is likely due to retrieval problems. The information must be consolidated from the short term memory to the long term memory.
Retrieval: Process of returning information from the long term memory to the short term memory. • Most retrieval is unconscious such as from social behaviour and object recognition • Retrieval is not necessarily the same as recall – e.g. ‘tip of the tongue’ phenomenon, where a word has failed to be retrieved properly from memory, combined with partial recall . • Retrieval easier if cues are present. • Retrieval and Emotion: Mood (especially low mood) can affect retrieval. Depressed participants tend to recall more negative personal events and recall more negative words from a word list.
Memory Problems • Anterograde Amnesia: Refers to sufficient memory for any information before accident, but severe deficits with learning new information. • Normal short term memory, but cant transfer information to long term (or is it a deficit with retrieval?) • No knowledge of current affairs, time of day or family events http://www.youtube.com/watch?v=Vwigmktix2Y • Retrograde Amnesia: Refers to a loss of information / forgetting what happened prior to accident. • Induced with clinical use of electric therapy (ECT)
