Consciousness and Imagery

CGS 2301, Jiahui Guo, Spring '25

Consciousness Definition

• Awareness of external events

• Awareness of internal situations

• Awareness of yourself as a unique being having experiences

• Awareness of your thoughts about these experiences

Reisberg (2019)

Consciousness is awareness of sensations or ideas, such that you can reflect on those sensations and ideas, know what it feels like to “experience” it, and report to others your awareness.

Components of Consciousness

• Wakefulness

• Awareness

Wakefulness

Level of arousal or alertness

Awareness

Clarity or specificity of content in consciousness.

Gazanaga, Ivry & Mangun, 2009

Sensory analysis is split into conscious and unconscious, conscious is split into attended and unattended, and attended becomes the conscious report.

Mental Imagery

Experiencing a sensory impression in the absence of sensory input.

Visual Imagery

“Seeing” in the absence of a visual stimulus.

Auditory Imagery

“Hearing” in the absence of an auditory stimulus.

Paivio (1963, 1965)

Memory for words that evoke mental images is better than those that do not (dual-coding theory).

Concrete Words

Words that are encoded both verbally and visually (tree, desk)

Abstract Words

Words that are encoded verbally only (truth, justice)

Conceptual-peg hypothesis

Concrete nouns create images that other words can hang onto, enhancing memory for these words

Shepard and Meltzer (1971)

Participants mentally rotated one object to see if it matched the other object: the time to respond strongly correlated with the angle of rotation.

Kosslyn (1973)

Takes longer to mentally move longer distances, suggesting that imagery, like perception, is spatial.

Kosslyn et al. (1978)

Island with 7 trips and 21 locations: Takes longer to scan between greater distances.

The Imagery Debate

Is imagery spatial or propositional?

Epiphenomenon

A phenomenon that accompanies a mechanism but is not actually part of a mechanism (light blinking to let you know computer is on)

Propositional Relationship

A mental representation in which relationships are portrayed by symbols.

Pylyshyn (1973)

Proposed that imagery is propositional, and suggested that spatial representation is an epiphenomenon.

Proposition representation

Symbols, Language

Spatial representation

Pictures

Tacit Knowledge Explanation

People unconsciously use knowledge about the world in making their judgements.

Pylyshyn (2003)

Suggests that Kosslyn’s results could be explained by using real-world knowledge unconsciously (tacit knowledge).

Finke and Pinker (1982)

Experiment that eliminated tacit knowledge, and still confirmed that a longer reaction time when the arrow was further away from a dot.

Comparing Imagery and Perception

Moving closer to an object lets you see more detail: Images are suggested to be spatial like perception.

Kosslyn (1978)

Mental Walk Task: Participants had to “move closer” to see smaller animals than large animals, they are quicker to detect details when an animal takes up a larger proportion of the visual field.

Perky (1910)

Participants asked to project mental images of common objects onto a screen, while the experimenter back-projected very dim images of the same objects. Their descriptions matched the projected images, suggesting they mistook the actual picture for their own mental image.

Farah (1985)

Participants imagined letters H or T on a screen, and then two squares would flash, one of them with the one of the two letters very faintly: target letter was more accurately determined when it was the same as the imagined letter.

LeBihan, et al. (1993)

Similar parts of the visual cortex (V1/V2)are activated during both perception and imagery tasks.

Krieman et al (2000)

Implanted electrodes in human epilepsy patients: Neurons respond to both perceiving and imaging an object.

Ganis, et al., (2004)

Almost a complete overlap of activation by perception and imagery in front of the brain, but there were differences in the visual cortex.

Amedi, et al., (2005)

Deactivation of non-visual areas of brain during imagery. Mental images are fragile, so less activation keeps other things from interfering.

Yoo, Lee, & Choi (2002)

People activate parts of the auditory cortex while imagining a “C Major”

Halpern et al. (2004)

Participants activated similar regions of the auditory cortex during perception and imagery of eight different musical instruments. Activation was less for the imagery condition than the perception condition.