COG Lecture 5 - Mental Imagery

Theories of Mental Imagery

• The pictorial theory suggests mental images are internal pictures, recreating external stimuli in our minds.
• The Functional Equivalence theory(Kosslyn 1980, Decety 1996) proposes mental imagery and actual perception share neural pathways and cognitive processes.
• Both imagined movements and physical actions use the same mental processes.
• Imagery internally unfolds a motor representation without physical movement.
• The Propositional Codes theory (Pylyshyn 2002) considers mental imagery an epiphenomenon linked to cognitive processes.
• Mental representations utilize abstract symbols instead of picture-like images.
• Imagery is independent of sensory and motor systems involving manipulating symbolic representations, rather than images themselves.
• Kosslyn argues imagery and perception use the same mechanism.
• Pylyshyn argues imagery and perception use completely different mechanisms.

Behavioral Evidence for Mental Imagery

• Shepard & Metzler (1971) studied mental rotation, assessing if two objects were the same or different.
• The study involved 2D-match (picture-plane pair), 3D-match (depth pair), and non-match conditions.
• Kosslyn et al. (1978) researched mental travel, requiring subjects to move between locations on a memorized map.
• Participants pressed a button upon mentally arriving at a centered dot.
• A linear relationship exists between the distance and mental travel time between locations.

Cognitive Neuro Evidence for Mental Imagery

• O’Craven & Kanwisher (2000) presented face or house pictures, then asked participants to close their eyes and vividly imagine the pictures.
• fMRI scans compared the fusiform face area (FFA) to the posterior parietal area (PPA).
• FFA is active during face perception and when imagining faces.
• PPA is active during house perception and when imagining houses.
• Mental imagery activates the same content-specific brain regions as visual perception.
• Kosslyn et al. (1999) had participants visualize stripes and compare properties
• There was a longer reaction time in the TMS condition, compared to the control (SHAM) condition.

Neuropsychological Evidence for Mental Imagery

• Bisiach & Luzzatti (1978) asked neglect patients to imagine being in Piazza Del Duomo in Milan and describe features.
• When imagining the square from one perspective, patients failed to mention details on left side of their mental image.
• When participants imagined the square from a rotated viewpoint (180°), they then recalled the previously omitted details, neglecting the side now on their left

Andrade et al. (1997)

• Participants identified personal memories and focused on the mental images associated with them.
• Dual-attention tasks involved participants performing eye movements (EM) ,complex tapping and fixed eyes (No-EM) while thinking of the memories.
• Eye movement tasks decreased the vividness of mental images compared to control.
• Mental images have properties similar to actual perception.

Limitations and Problems

• The results might be affected by participants' implicit knowledge or expectations about the physical world.
• Pylyshyn (1981) researched tacit knowledge.
• The first experiment involved participants scanning from one place to another on a mental map
• The time it took to "scan" related to the distance between places.
• In the second experiment, participants gave compass directions, where distance didn't matter.
• The "scanning" effect is suggested to be expectations about how long things should take.
• Tacit knowledge is implicit, unconscious knowledge or expectations that people have about the world.
• Tacit knowledge can influence how people perform tasks like mental rotation or scanning.
• Simulation of real-world experiences can happen as well.
• Experiments might be due to participant implicit expectations.
• Mental images get shaped by what is known/expected, rather than sensory information.
• Performance on imagery tasks may not match performance on related perceptual tasks.
• Servos & Goodale (1995) did research on the problem of dissociation.
• Patient (D.F.) with agnosia had difficulty in perceiving/discriminating object shapes, sizes, and orientations.
• DF showed normal visual imagery despite profound deficits in visual form perception.
• Dissociation between impaired perception and preserved imagery challenged the notion those processes share a network.
• Different individuals have varying abilities when it comes to mental imagery.
• Individual differences, Zeman, Dewar & Della Salla (2015), some neurotypical people are even 'aphantasic'

Interim Summary

• Imagery is not a single, undifferentiated ability
• Different types of imagery activate different brain areas
• Precise relationship between imagery and perception remains unclear, but may involve both depictive and propositional representations (Pearson & Kosslyn 2015)
• Behavioural evidence open to different interpretations
• Some evidence for overlapping brain systems, but neuropsychology evidence is hard to interpret
• Other evidence for separate systems
• Evidence seems more consistent with separate modules for imagery and perception

Functions of Mental Imagery-Paivio (1985)

• Paivio discovered imagery has two functions.
• Imagery has two levels.
• Imagery distinguishes between imagery content and imagery function.
• Cognitive function involves making spatial judgements and skill rehearsal.
• Motivational functions involve achievement of a specific goal.

Cognitive Specific Imagery

• It focuses on rehearsing and improving specific skills.
• Its purpose is to enhance the execution of particular sport-specific skills/movements.
• Athletes use it to perfect techniques, improve motor skills and enhance muscle memory.
• Driskell et al., (1994) conducted a meta-analysis of the literature on mental practice to determine its effects on performance.
• Findings suggested that mental practice has a significant positive effect, though not as big as real practice.
• Analysis showed that experts and novices could benefit, but the effects are stronger for experts

Cognitive General Imagery

• It focuses on rehearsing strategies, game plans and tactical elements.
• Its purpose is to enhance an athlete's ability to execute complex game strategies.
• Athletes use this before competition to prepare the game plan. Also during practice and competition, and to learn new strategies.

Motivational Specific Imagery

• It focuses on visualizing goals and behaviours.
• It is to enhance motivation and increase effort towards achieving specific performance goals

Motivational General Imagery

• Motivational General-Arousal imagery is to regulate arousal and stress levels before or during competition.
• Athletes visualize being excited, relaxed, or focused before an event and managing anxiety.
• Is can help athletes achieve optimal arousal levels (e.g. Hanin 1987)
• Motivational General-Mastery imagery is to enhance self-confidence, mental toughness, and focus.

In Summary

• Imagery appears to use much of the same machinery as perception, although this may reflect tacit knowledge.
• Underlying representation may be propositional
• Imagery is used to practice specific skills/modulate arousal.
• Mental practice can be successfully applied to many domains such as sport & exercise and psychiatric disorders.