Understanding Metaphors: Is the RH uniquely involved?
1
Davis ,
Reaction Time
Empirically, most research with brain-injured individuals suggests that
the right hemisphere (RH) is preferentially involved in understanding
figurative language (e.g., Brownell et al., 1990; Kempler et al., 1999).
Although this hypothesis is supported by some investigations of noninjured participants (Anaki et al., 1998; Bottini et al., 1994), a growing
number of studies have failed to provide evidence for this claim (e.g.,
Coulson & Van Petten, 2000; Lee & Dapretto, 2003). These investigations,
however, have used widely different methodologies making it difficult to
draw any firm conclusions.
Theoretically, the RH is suggested to be better suited for comprehending
figurative language because RH meaning activation is broader and
maintained longer, even in the event of contextual inconsistency (Anaki
et al., 1998 Beeman, 1998; Burgess & Simpson, 1988; Faust & Chiarello,
1998). The LH, in contrast, maintains the activation of only the most
dominant, closely related, and contextually consistent aspects of
meaning. The LH is also claimed to be better at grammatical and
syntactic processing than the RH, which is less sensitive to sentence
constraints (Faust, 1998).
PURPOSE - The present study examined the extent to which each
cerebral hemisphere is typically involved in understanding metaphors of
increasing linguistic complexity. Non-brain-injured individuals were
investigated using a divided visual field priming paradigm.
PREDICTIONS - According to most previous empirical and theoretical
claims, the LH was expected to have difficulties processing metaphoric
meaning, particularly in minimal or ambiguous contexts, but not when
presented in a supportive unambiguous sentence. RH meaning activation,
on the other hand, was predicted to be generally broad and
unconstrained.
Experiment 1
20
Literal
Metaphor
15
10
5
Literal
1
Metaphor
0
100
200
800
-1
0
100
200
800
40
30
Metaphor
20
10
SOA (ms)
SOA (ms)
Unambiguous
100
200
800
2
Literal
Metaphor
0
RT Priming (ms)
3
-1
30
10
0
Consistent
Unambiguous
Literal
Metaphor
20
800
10
Unambiguous
Sentence Context Condition
Literal
2
1
Literal
Metaphor
2
Inconsistent
Sentence Context Condition
Reaction Time
3
Metaphor
Experiment 3: Results for LVF / RH
4
1
Accuracy
50
40
30
Literal
20
Metaphor
10
0
Ambiguous
3
Consistent
Sentence Context Condition
0
Ambiguous
4
0
Inconsistent
5
30
SOA (ms)
Literal
Metaphor
20
Accuracy
40
-2
SOA (ms)
40
Sentence Context Condition
50
200
1
Ambiguous
4
100
2
Reaction Time
1
Literal
Metaphor
5
50
Experiment 2: Results for LVF / RH
Accuracy
Literal
Metaphor
3
Sentence Context Condition
Experiment 1: Results for LVF / RH
Reaction Time
4
0
Ambiguous
-2
-10
40
35
30
25
20
15
10
5
0
-5
-10
Literal
Priming (% corr)
-5
2
5
50
Priming (% corr)
25
3
RT Priming (ms)
30
Priming (% correct)
RT Priming (ms)
35
Accuracy
Reaction Time
Accuracy
4
Priming (% correct)
Introduction
40
RT Priming (ms)
Research with brain-injured individuals suggests that the right
hemisphere (RH) is preferentially involved in understanding figurative
language, whereas evidence from non-injured participants has been
mixed (Anaki et al., 1998; Coulson & Van Petten, 2000). We conducted
several divided visual field priming experiments examining each
hemisphere’s involvement in comprehending metaphors of increasing
linguistic complexity. Experiments 1 and 2 investigated ambiguous
words with literal and metaphoric meanings in single word and
sentence contexts, while Experiment 3 involved standard metaphors
(e.g., His girlfriend’s face was a storm). Although some RH metaphor
priming was obtained in both sentence and single word priming
conditions, results did not strongly support the RH figurative language
hypothesis. Metaphor priming also occurred in the LH at early timecourses (100 ms SOA), or when supported by a sentence context.
Results are discussed in terms of current theories of cerebral
asymmetries for processing language, and theories of metaphor
comprehension.
Reaction Time
Accuracy
Priming (% corr)
Abstract
Experiment 3: Results for RVF / LH
Experiment 2: Results for RVF / LH
RT Priming (ms)
Experiment 1: Results for RVF / LH
University of California,
2
Riverside
Priming (% corr)
University of California,
and Christine
2
Chiarello
RT Priming (ms)
Natalie A.
1
Kacinik
Unambiguous
Sentence Context Condition
5
4
3
Literal
Metaphor
2
1
0
Consistent
Inconsistent
Consistent
Sentence Context Condition
Inconsistent
Sentence Context Condition
Experiment 3: Results & Discussion
Experiment 1: Results & Discussion
Experiment 2: Results & Discussion
•RVF/LH - Equivalent priming for literal and metaphor targets at brief
•RVF/LH – Similar literal and metaphor priming with both contexts, but
•RVF/LH – Literal and metaphor targets primed to similar degree when consistent with sentence, but no
SOAs, but no metaphoric priming at long SOA. This indicates that ALL
aspects of meaning are initially activated by the LH, but ONLY the
literal meaning is selected and maintained later in time-course.
greater facilitation following unambiguous sentences. LH processes thus
take advantage of semantic, grammatical, and syntactic constraints to
maintain the activation of ALL aspects of meaning (literal or metaphoric)
consistent with the sentence context, even if it is ambiguous, rather
than selecting and maintaining the activation of only the dominant
literal meaning.
priming for either target when contextually inappropriate. LH processes thus select and maintain the activation
of only contextually relevant aspects of meaning, regardless of whether they are literal or metaphoric per se.
•LVF/RH - Literal priming across SOAs (RT & ACC). Metaphoric priming
only in ACC, but constant over time. Thus, the degree of RH semantic
activation varies for different aspects of meaning. Literal meanings
were activated more strongly than the metaphoric sense, although this
weak metaphoric activation was maintained across time.
•CONCLUSIONS - Time-course and the type of semantic relation
modulate the extent of literal and metaphoric meaning activation in
BOTH hemispheres.
•Minimal evidence for preferential RH involvement in metaphor
comprehension resulting from more bottom-up semantic activation
processes.
•This experiment, HOWEVER, was limited to the literal and metaphoric
meanings of individual words.
•LVF/RH – Very similar to RVF/LH results. Equivalent literal and
metaphor priming with both contexts, but greater facilitation after
unambiguous sentences. In contrast to Experiment 1, these findings
show that the RH can strongly activate and maintain the activation of
metaphoric meanings if there is contextual support, indicating that RH
processes also benefit from the activation of words in the sentence,
even if the context is vague.
•CONCLUSIONS – This experiment still fails to support the hypothesis
of the RH as preferentially involved in metaphor comprehension because
the LH was also able to understand and activate metaphoric meaning to
a similar degree, even after ambiguous sentences.
Experiment 3
Experiment 2
•LVF/RH – Similar literal and metaphor priming when contextually consistent. No priming for inconsistent
metaphor targets, but irrelevant literal aspects of meaning were primed. RH processing of metaphoric
sentences results in a broader activation of meaning than the comprehension of literal sentences, such that
inconsistent literal aspects of meaning remain active. This could be advantageous if an initial interpretation
needed to be revised.
•CONCLUSIONS - As in Experiment 2, literal and metaphor aspects of meaning were active in both
hemispheres when targets were consistent with the meaning of the sentence, indicating that both hemispheres
are able to understand metaphors involving more complex sentence integration processes.
•Metaphoric aspects of meaning were not primed after literal sentences (in either hemisphere) indicating that
metaphoric meaning only emerges upon comprehension of the metaphoric expression as a whole.
General Conclusions
•LH processes were extensively involved in understanding metaphors, and RH meaning activation was considerably affected by
different sentence contexts.
•Any hemisphere differences for understanding literal and metaphoric language can’t be explained according to general
differences in the breadth of meaning activation because time-course, and especially sentence contexts, significantly
modulated the degree of literal and metaphoric meaning activation in both hemispheres although in slightly different ways.
•Indeed, literal and metaphor priming effects in each hemisphere were remarkably similar across the study as a whole.
PURPOSE – To investigate cerebral asymmetries in the timecourse of literal and metaphoric meaning activation of lexical
metaphors (ambiguous words with literal and metaphoric
meaning) in a single word priming paradigm.
METHOD – Three SOAs (100, 200, & 800 ms) with 32 righthanded native English speakers run at each. Centrally
presented primes and lateralized targets. The target task was
lexical decision.
Rel Word Prime
Unrel Nonword Prime
Literal Target
Metaphor Target
flaky
grony
CRUST
SISTER
grasped
prolled
RAILING
IDEA
bright
glomed
COLORS
STUDENT
PURPOSE – To investigate hemispheric differences for literal vs
metaphoric meaning activation of lexical metaphors, going from
ambiguous sentence contexts ->
We all admired the bright COLORS vs STUDENT
to more constrained unambiguous sentences ->
It’s the building with the bright COLORS
The teacher praised the bright STUDENT
METHOD – 64 right-handed native English speakers performed lexical
decisions to lateralized targets after incomplete sentence primes.
PURPOSE – To investigate cerebral asymmetries for standard “an X is a Y”
metaphors (e.g., His girlfriend’s face was a storm), and the extent to
which each hemisphere maintains the activation of contextually appropriate
(e.g., ANGRY) and inappropriate meanings (e.g., CLOUDS).
•The RH can’t generally be considered the preferred substrate for metaphor comprehension, but it is involved (as is the LH)
and may play a unique role in maintaining broadly activated meanings in the event an original interpretation needs to be
modified.
Referemces
METHOD – Literal and metaphoric sentences with targets related to the
literal and metaphoric meaning were presented in a fully-crossed design:
His girlfriend’s face was a storm – ANGRY
His girlfriend’s face was a storm – CLOUDS
The ship was headed toward a storm – CLOUDS
The ship was headed toward a storm - ANGRY
Anaki, D., Faust, M., & Kravetz, S. (1998). Cerebral hemispheric asymmetries in processing lexical metaphors. Neuropsychologia, 36, 353-350.
48 right-handed native English participants were presented with the full
sentences as primes and performed lexical decisions on the lateralized
Faust, M. (1998). Obtaining evidence of language comprehension from sentence priming. In M. Beeman & C. Chiarello (Eds.), Right hemisphere language
comprehension: Perspectives from cognitive neuroscience (pp. 161-182). Mahwah, NJ: Erlbaum.
targets.
Kempler, D., Van Lancker, D., Marchman, V., & Bates, E. (1999). Idiom comprehension in children and adults with unilateral brain damage. Developmental
Neuropsychology, 15, 327-349.
Beeman, M. (1998). Coarse semantic coding and discourse comprehension. In M. Beeman & C. Chiarello (Eds.), Right hemisphere language comprehension:
Perspectives from cognitive neuroscience (pp. 255-284). Mahwah, NJ: Erlbaum.
Bottini, G., Corcoran, R., Sterzi, R., Paulesu, E., Schenone, P., Scarpa, O., Frackowiak, R. S. J., & Frith, C. D. (1994). The role of the right hemisphere in the
interpretation of figurative aspects of language: A positron emission tomography activation study. Brain, 117, 1241-1253.
Brownell, H. H., Simpson, T. L., Bihrle, A. M., Potter, H. H., & Gardner, H. (1990). Appreciation of metaphoric alternative word meanings by left and right braindamaged patients. Neuropsychologia, 28, 375-383.
Burgess, C., & Simpson, G. B. (1988). Cerebral hemispheric mechanisms in the retrieval of ambiguous word meanings. Brain & Language, 33, 86-104.
Coulson, S., & Van Petten, C. (2000). ERPs to parafoveally presented metaphors: The role of the right hemisphere. Poster presented at the 7th annual meeting
of the Cognitive Neuroscience Society, San Francisco.
Faust, M., & Chiarello, C. (1998). Lexical ambiguity resolution by the two hemispheres. Neuropsychologia, 36, 827-836.
Lee, S., & Dapretto, M. (2003). Metaphorical vs. literal word meanings: fMRI evidence against a selective role of the right hemisphere. Poster presented at the
10th annual meeting of the Cognitive Neuroscience Society, New York.