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Lecture3:Chapter5-Perception..Dr.Anna
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Lecture3:Chapter5-Perception..Dr.Anna

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this is the book lecture power point not the one we are taking in the lecture. things from this power point are not necessary.

this is the book lecture power point not the one we are taking in the lecture. things from this power point are not necessary.
date: 31/1/2013

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    Lecture3:Chapter5-Perception..Dr.Anna Lecture3:Chapter5-Perception..Dr.Anna Presentation Transcript

    • Chapter 5 PerceptionUse with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • What is the Use of Perception?• Processing & using incoming sensory information – Humans require models of the environment to base perceptions, decisions and behaviour on – To create & maintain models, they need to acquire raw sensory information & organize this into a coherent structure• Five functions of perception – Need to decide which information to process, where object of interest is, recognise what object of interest is, abstract the critical features of the object and keep appearance of the object constant Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Attention• Selective attention – Refers to the process by which we attend to certain stimuli and ignore others – Eye movements – studies of visual attention monitor people’s eye fixation patterns which attend to features most likely to distinguish scene for other similar scenes• Auditory attention – Also use selective attention in audition, e.g. by focusing on the direction the sound is coming from and features of the speaker’s voice, e.g. pitch and intonation Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Attention• Attention, perception, and memory – We are consciously unaware of, and remember little about unattended stimuli• Costs & benefits of selectively attending to stimuli – One cost of selective attention is that observers are often oblivious to other, potentially important, stimuli in the environment – That people are able to switch attention between sets of information can be beneficial e.g. in medicine for the treatment of cataracts Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Localization• To localize objects, need to first separate them and then organise them into groups• Separation of objects – Figure and ground – in stimulus with two or more distinct regions, usually see part as figure (contains objects of interest) and rest as ground (or background) Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Localization• ...Separation of objects – Grouping of objects - according to several determinants – proximity to each other, similarity, good continuation or closure. These serve to create most stable and simple forms possible within a given pattern• Perceiving distance – To know where object is, we use depth cues • Binocular cues – brain uses information from eyes to infer depth • Monocular cues – for distant objects we use environmental information e.g. perspective, interposition, relative size & height, shading & shadows and motion Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Localization• Perceiving motion – To move around environment effectively need to know direction of moving objects either using stroboscopic motion (illusion of motion) or real motion Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Recognition• Recognising object requires that the features of an object are correctly bound together• Global-to-local processing – To know what object is, use the context (the scene) to make inferences – global processing (what the scene is) followed by local processing (using knowledge about scene to identify object) Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Recognition• The binding problem: pre-attentive & attentive processes – Feature integration theory – information about primitive features of an object acquired via pre-attentive processes, and then integrated in subsequent attentive processing stage (using attention to “glue” features together) – Problems with the feature integration theory because research has found too many “primitives” to be realistic. Dynamic control theory proposed – system rearranges itself for different tasks Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Recognition• Determining what an object is – Shape plays critical role in determining what object is – Visual processing – early stages use information on the retina to create description, later stages use comparison with visual memory to select best match – Feature detectors in the cortex – three types of cell • Simple cells – respond when eye exposed to line stimulus at particular orientation and position within receptive field • Complex cells – also respond to bar or edge in particular orientation but do not need specific position • Hypercomplex cells – require stimulus to be in a particular orientation and of particular length Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Recognition• ...Determining what an object is – Relations among features – to describe a shape also need to specify how features combine/relate• Later stages of recognition: network models – Simple networks – knowledge of features associated and not associated with shapes contained in network of connections (connectionist model) for comparison – Networks with feedback – easier to perceive letter as part of word than alone because the word is an additional source of activation for letter – therefore have top-down feedback connections which aid recognition Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Recognition• Recognising natural objects & top-down processing – Features of natural objects • More complex than lines – similar to simple geometric forms, e.g. cylinders, cones, blocks and wedges. Particular set of such forms is a geon – The importance of context • Bottom-up processes driven solely by the input (sensory data), whereas top-down processes driven by person’s knowledge, experience, attention and expectations • When the context is appropriate (that is, it predicts the input object), it facilitates perception; when the context is inappropriate, it impairs perception Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • RecognitionUse with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Recognition• Special processing of socially relevant stimuli: face recognition – Development of special face recognition processes • Three sources of evidence – prosopagnosia – brain injury where person able to recognise objects but not faces; inversion effect – faces hard to recognise upside down but not objects; and face and object recognition develop differently in children – Failure of recognition – happens routinely for people with certain kinds of brain damage (agnosia) Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Abstraction• Exact to abstract – Only need to know enough visual detail to carry out whatever task is requiring you to perceive the object• The advantages of abstraction: required storage and processing speed – More efficient to perceive and encode an abstraction of an object than exact representation in memory – Because abstraction uses less space, faster to work with – Information retained is the critical information needed Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Perceptual Constancies• The nature of constancy – What we perceive is perception of what object is actually like rather than perception based only on the “objective” physical information acquired from environment• Color and brightness constancy – Color constancy – ability of visual system to perceive the reflectance characteristic (an inherent property of the object) – no matter what the source wavelengths (light source – sun/light bulb etc.) Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Perceptual Constancies• ...Color and brightness constancy – Brightness constancy – perceived lightness of object changes very little (if at all) even when intensity of source changes significantly Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Perceptual Constancies• Size constancy – An object’s perceived size remains relatively constant no matter how far away it is – Dependence on depth cues – perceived size of an object increases with both the retinal size of the object and the perceived distance of the object (known as the size-distance invariance principle)• Constancies in all sensory modalities – Although visual constancies most salient, constancies exist in all sensory modalities Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Perceptual Constancies• Illusions – Perception differs systematically from physical reality, often because visual system tries to maintain constancy Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Divisions of Labor in the Brain• The neural basis of attention – Three brain systems in attention • One system functions to keep us alert while the other two systems seem to mediate selective attention, the first (posterior system) by orienting attention to the stimulus on basis of location, shape or color, while the second (anterior system) controls when and how these features will be used for selection – Neural processing on attended objects • Regions of the brain that are relevant to attribute being attended to (e.g. color) will show increased activity Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Divisions of Labor in the Brain• The visual cortex – Visual cortex operates according to the principle of division of labor – different regions specialised for different perceptual functions• Recognition versus localization systems – Recognition depends on branch of visual system which includes primary visual cortex and a region near the bottom of the cerebral cortex, while localization depends on branch of visual system which includes primary visual cortex and a region of the cortex near the top of the brain Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Perceptual Development• Nature and nurture – Research seeks to assess contribution of nature and nurture in perceptual development and identify interactions• Discrimination by infants – Methods of studying infants • Preferential looking method – infant’s tendency to look at some objects more than at others • Habituation method – allow infants to look at an object until bored (habituated to it) and then present new object and measure time looking at it Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Perceptual Development• ...Discrimination by infants – Perceiving forms • Visual acuity develops rapidly over the first six months, then more slowly until reaches adult levels between 1-2 years • Sensitivity to some shape features of objects appears very early in life, e.g. three-day-old infant will direct eye movements to edges when presented with triangle – Perceiving depth • Depth perception begins to appear at three months but not fully established until about six months Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Perceptual Development• ...Discrimination by infants – ...Perceiving depth Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Perceptual Development• ...Discrimination by infants – Perceiving constancies • Also starts to develop in first few months of life, particularly for shape and size constancy• Controlled stimulation – Absence of stimulation • Animals raised in darkness suffered permanent visual impairment suggesting that there is a critical period early in life when lack of normal stimulation produces deficiency in innate perceptual capacities Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning
    • Perceptual Development• ...Controlled stimulation – Limited stimulation • Animals receive stimuli in both eyes but only certain kinds – leads to deficiency in stimuli they do not receive. Facts indicate that certain kinds of stimulation essential for development and maintenance of perceptual capacities present at birth – Active perception • Learning plays major role for coordinating perceptions with motor responses Use with Atkinson & Hilgard’s Introduction to Psychology 15th edition Nolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning