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Psychology - Honours year > Mike Nicholls > Flashcards

Flashcards in Mike Nicholls Deck (16):
1

What are the three hypotheses for why portraits tend to display more of the sitter's left-face?

1. Mechanical Preference of the artists
2. Asymmetries in aesthetic preferences
3. Preference to portray features on the left side of the face

2

Outline the "mechanical preference of the artist" hypotheses of the leftward laterality of expression in portraiture.

Although left-handers are overrepresented in the artist group, there are still more right handers.

Dextral artists (Right handers) may prefer to draw portraits with more left-face because doing so allows them to use abductive movements (which move with the natural swing of the arm) to make the curve of the face, resulting smoother and neater lines. compared to adductive movements, where the movement is against the natural arc of the arm.

The opposite would be true of sinistral artist (left handers)

3

What evidence is there for the "mechanical preference of the artist" hypotheses of the leftward laterality of expression in portraiture?

Although left-handers are overrepresented in the artist group, there are still more right handers.

Dextral artists favouring abductive movements to draw could explain the leftward face portraiture bias.

4

What evidence is there AGAINST the "mechanical preference of the artist" hypotheses of the leftward laterality of expression in portraiture? (4 items)

1. IF this hypothesis is true then samples of portraits done by left-handed artists should not have the leftward face bias. - However, this is not the case, left-hand painters "Raphael" and "Hans Holbien the younger" still demonstrate leftward bias.

2. Self-portrait painters appear to have a right-ward bias, if left-face was a practical mechanical preference then it should occur for self-portraits - it doesn't (they probably used mirrors!)

3. Photography does not require artists to draw the curve of the face at all, yet a leftward face bias still exists in portrait photos.

4. Cannot explain why the bias is stronger in women.

5

Outline the "Perceptual asymmetries of the viewers" hypotheses of the leftward laterality of expression in portraiture.

It may be that the lateral organisation of the viewers brain affects aesthetic judgements.

There is evidence to suggest that features on the left-side of a painting/portrait are perceived as more salient and closer than those on the right-side. This may be related to right hemisphere lateralisation for face recognition. When a portrait is painted with a left-facing, more facial details fall in the left half of the painting.

Chimeric facial stimuli support this proposition - When asked to choose the 'happier' picture from two faces, one with happy expression on the left and sad on the right and the other with sad expression on the left and happy on the right - people tend to select the stimulus with the happy expression on the left-side. Suggesting a biased attention towards the left-side.

6

What evidence is there for the "Perceptual asymmetries of the viewers" hypotheses of the leftward laterality of expression in portraiture?

Chimeric facial stimuli support this hypothesis - When asked to choose the 'happier' picture from two faces, one with happy expression on the left and sad on the right and the other with sad expression on the left and happy on the right - people tend to select the stimulus with the happy expression on the left-side. Suggesting a biased attention towards the left-side.

7

What evidence is there AGAINST the "Perceptual asymmetries of the viewers" hypotheses of the leftward laterality of expression in portraiture?

1. Explanations based on perceptual biases cannot explain why a right ward bias exists for self-portraits - i.e., why the artist would want to portray themselves is a less desirable light

2. Nor does it explain differences between men and women. i.e., unlikely that men would want to portray themselves in a less desirable light.

3. When viewers rate original and mirror-reversed portraits - attractiveness or potency of a portrait was determined by the side of the (original) face shown NOT by the direction that the sitter appeared to be facing.

8

Outline the "Preference to portray features contained on the left side of the face" hypotheses of the leftward laterality of expression in portraiture.

People intuitively know which side (usually the left) of their face will better express emotion and choose to portray these features.

9

What evidence is there for the "Preference to portray features contained on the left side of the face" hypotheses of the leftward laterality of expression in portraiture?

1. Left-side of face produces more emotional expression
-- The left-side of the face produces a more intense expression than the right side (usually) (Borod et. al. 1997)
-- when viewers rate original and mirror-reversed portraits, attractiveness or potency of a portrait was determine by the side of the face shown by the model, not by the direction they appeared to be facing.
---------may relate to the left side of the face being controlled by the right cerebral hemisphere which is dominant for emotional expression.

2. When emotion is manipulated, such that half participants are asked to pose for a 'impassive' researcher portrait and the other for an 'emotive' family-gift portraits - the emotional context has an effect on the lateral bias in posing behaviours. Impassive condition has significantly less left-face than emotive condition (and the scripts overrode gender!) Suggests models intuitively know which side of their face most effectively expresses emotion. This could be ontogenetic (own life development) or phylogenetic (evolution of the species) [see Ekman and Darwin regarding facial expression universality]

3. Can explain the gender different in lateral posing bias. Females more emotive = more left face.

4. Right-face bias in self-portraits due to the mirror used to paint the self portrait

10

Which side of the mouth moves more during speech?

The right side of the mouth moves more than the left during speech. - research measuring movements made by the mouth has revealed that the right side of the mouth opens earlier and wider during speech production.


_____________________________
* This has been observed even in 5-years olds syllabic babbling and in common marmosets during social contact calls. Articulation clearer when right side of mouth not restrained.

* asymmetries in mouth movements may also affect the visual communication of speech. (lip-reading).

*Chimeric pictures each side articulating a different sound, asked to identify what sound was being made by each side - easier to identify based on right side. BUT when included mirror-reversed versions suggested also influence by left-field bias. (left hemi-space)

11

Why is the right side of the mouth usually more expressive for speech?

The right side of the mouth is innervated by the left cerebral hemisphere, increased movement of the right-mouth probably reflects left-hemisphere dominance for speech production. for 95% of the right-handed (Dextral) population.

12

What is the McGurk Effect?

An illusion in which incongruent lip movements cause listeners to miss report sounds.

* E.g., if the mouth movements of "ga" are dubbed over the sound "ba" a fusion of the two (e.g., "da") is often reported (McGurk & MacDonald, 1976)

13

What does the McGurk effect show?

This effect demonstrates that visual processing affects auditory experience in normal individuals.

14

When are McGurk type errors more frequent?

The more visual information there is!

15

In Nicolles et al. 2004, how did they test asymmetries of speech?

Right or left side of mouth covered in stimuli + baseline condition with neither side covered. + included mirror-reversed version of the stimuli. -


Details....

Visual-sound parings of: Ba, Ga, Pa, Da =

Control stimuli consisted of a soundtrack that matched the visual images - e.g., visual 'ba' combined within audio ba, visual ga combined with audio ga.

Experimental stimuli - 6 cased in which the soundtrack did not match the visual image ba-ga, ba-da, pa-da were designed to elicit combination responses.

Also a mirror-reversed version of the six vision-sound pairs.

Images were edited so that the right, the left, or neither side of the mouth was covered by a bar. the side of the bar changed according to the side of th speaker's mouth and covered half of the mouth.


* three possible response errors - fusion (E.g., for vision-sound pair ba-ga, "da" is reported". Combination responses (e.g., for vision-sound pair ba-ga, "Bga" is reported. Lip-reading responses (for vision-sound pair ga-ba, "ga" is reported.) (most errors were fusion errors > lipreading > combination)

16

In Nicolles et al. 2004, what was found? (asymmetries of speech) (what does this suggest?)

* Left-side covered (right-mouth visible) and neither side covered has same error rate - suggesting similar amounts of visual information.

* Right side covered had lower errors (left-mouth visible) - less visual info

THUS, the right side of the mouth is MORE IMPORTaNT than the left in generating the McGurk effect- in turn suggesting hat the right-mouth is more visually expressive than the left-mouth during speech.

MOREVER - when neither side of the mouth was covered, normal orientation (right-mouth in the viewers left-field) had as many errors as left-side covered (Right-mouth visible) errors (i.e., because more info).- suggests attention to left-field.

The right side of the mouth is important in the visual expression and comprehension of speech. Probably due to the lateralisation for speech in the left hemisphere (evolutionary origin).