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Chapter 6: Imagery “The mental representation of something that is not physically present”.
Preview and Introduction • Examples of imagery • How common is the use of imagery? Kossylyn & others (1990). • Most common type was _____________ • Typical history of the study of imagery • Wundt, Behaviourism, others, Cognitive Revolution
3 main topics related to mental imagery • 1) The nature of mental images, with emphasis on the way in which mental images are represented in the mind • 2) Cognitive neuroscience research on different types of mental images • 3) Cognitive (mental) maps
The Characteristics of Mental Images • Mental images are the mental representation of something that is not physically present. • The general question concerns the nature of these mental representations. • The specific question is whether mental images are represented in the brain in an analog (picture-like) or propositional (verbal-like) code? • Research on mental images is difficult to conduct, since mental images are not directly observable and they don't last long typically.
Analog Code View • Holds that images of object bear a close resemblance to the physical objects or events that they represent. • Holds that a visual mental image is like a "picture in our head“ • If true, ………………………
Propositional Code View • Holds that the mental representations for images are propositions -- a general abstract …………………………… • Propositional code does not physically resemble the original stimulus (it is abstract). • Storage is verbal-like (rather than picture-like) • Example of difference between the 2 viewpoints • Two types of codes for a “housefly”
Logic of Research • If analog code view is correct then operations performed on mental images will be similar to operations performed on the corresponding physical object. • Rotation of a mental image …………………... • Judgements about size and shape should be ……………. • A mental image should interfere with …………………… • We should be able to discover 2 interpretations of a mental image of ………………. • We should be able to produce illusions and ………………..
Preview of Research • Analog code evidence • 1. Imagery and mental rotation • 2. Imagery and size. • 3. Imagery and shapes. • 4. Imagery and interference. • 5. Other vision-like processes • 6. Neuroscience evidence • Propositional code evidence
Imagery and mental rotation • Shepard and Metzler (1971) • Task is to decide whether or not two block figures are the same or different. • Results shown in Fig. 6.1 on p. 198 • Findings from other studies described in text (p. 199) • Strong support for ……………… view
Imagery and Size • The size of mental images corresponds to the size of physical objects. • Kossylyn (1975) method and results • Same result would occur with real objects or pictures of the objects? • Supports correspondence between ………….. • Follow-up expts. shows similar results and ruled out other explanations. Read about them. • Jolicoeur and Kosslyn (1985) rule out …………..
Imagery and Shape • Paivio's (1978) "mental clocks" experiment. • Which time forms a smaller angle: 3:20 or 7:25? • Results (See Fig. 6.4 on p. 205): • 2 important results • Shows correspondence between mental images and real physical objects again supporting ……………. • Shepard and Chipman's "shape of states judgement" experiment. • The shape of mental images (for states of the U.S.) matches the shape of real physical objects (picture outline of the states).
Imagery and Interference • Research has indicated that visual imagery can interfere with visual perception (and vice-versa). • interferes with • visual perception <---------------------> visual imagery • Segal and Fusella (1970) found that maintaining a visual image can interfere with a visual detection task. • Method • Results
Imagery and Interference • Wexler & others (1998) showed that an actual motor movement can interfere with a mental movement of an image • Method • If physical movement was opposite to “mental movement” decision time was slower.
Other Vision-like Processes • Other similarities between the perception of mental images and the visual perception of real objects (supports analog code position): • Two similarities discussed.
Neuroscience Evidence • No similarity between imagery and visual perception at lower levels of visual system (rods and cones) • At higher levels, the same brain structures may be active during both imagery and visual perception: • Farrah (1988) found that ………………….. • If damage to visual cortex and other visual processing areas, then visual perception and visual imagery is impossible (Farrah, 2000). • Kossylyn & others (1996) brain imaging study • Auditory imagery • Areas in the auditory cortex become active when people imagine hearing popular songs. • Motor Imagery
Imagery and Ambiguous Figures • Reed's (1974) "detection of hidden figures" experiment • Method • Resulats: • Reed, therefore, concluded that the ……….. was supported.
Imagery and Ambiguous Figures II • Chambers & Reisberg (1985) • Method • Results • Finke & others found that certain types of mental images for figures can …………………
Review of Research • Analog code evidence • 1. Imagery and mental rotation • 2. Imagery and size. • 3. Imagery and shapes. • 4. Imagery and interference. • 5. Other vision-like processes • 6. Neuroscience evidence • Propositional code evidence • Ambiguous figures
Revisiting the Imagery Controversy • The Analog Code Position of Kosslyn & Thomson (2000) • Subsystems used by both visual imagery and visual perception include attention shifting, encoding of properties (shape, colour), and spatial properties (location) • The Propositional Code Position of Plyshlyn • Basic level of storage is propositional but analog visual images can be generated from these propositions. • Picture-like mental images would take up too much space. • Emphasizes differences between mental images and perceptual experiences (flashlight example in text) • Hard to disprove.
Matlin’s Conclusions • Matlin concludes that with most stimuli and most tasks, images seem to be represented …………………… • For some stimuli and some specific tasks, a _______________ code may be used. • In many respects -- though not all -- operations performed on mental images resemble the ______________________________