Perceptual foundations of abstract thought

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2005.Includes bibliographical references (p. 75-78).How do people think about things they can never see or touch? The ability to invent and reason about domains such as time, ideas, or mathematics is uniquely human, and is arguably the hallmark of human sophistication. Yet, how people mentally represent these abstract domains has remained one of the great mysteries of the mind. This dissertation explores a potential solution: perhaps the mind recruits old structures for new uses. Perhaps sensory and motor representations that result from physical interactions with the world (e.g., representations of physical space) are recycled to support our thinking about abstract phenomena. This hypothesis is motivated, in part, by patterns observed in language: in order to talk about abstract things, speakers often recruit metaphors from more concrete or perceptually rich domains. For example, English speakers often talk about time using spatial language (e.g., a long vacation; a short meeting). Cognitive linguists have argued such expressions reveal that people conceptualize abstract domains like time metaphorically, in terms of space. Although linguistic evidence for this Conceptual Metaphor Theory is abundant, the necessary nonlinguistic evidence has been elusive.(cont.) In two series of experiments, I investigated whether mental representations that result from physical experience underlie people's more abstract mental representations, using the domains of space and :!I.:e as a testbed. New experimental tools were developed in order to evaluate Conceptual Metaphor Theory as an account of the evolution and structure of abstract concepts, and to explore relations between language and nonlinguistic thought. Hypotheses about the way people represent space and time were based on patterns in metaphorical language, but were tested using simple psychophysical tasks with nonlinguistic stimuli and responses. Results of the first set of experiments showed that English speakers incorporate irrelevant spatial information into their estimates of time (but not vice versa), suggesting that people not only talk about time using spatial language, but also think about time using spatial representations. The second set of experiments showed that (a) speakers of different languages rely on different spatial metaphors for duration, (b) the dominant metaphor in participants' first languages strongly predicts their performance on nonlinguistic time estimation tasks, and (c) training participants to use new spatiotemporal metaphors in language changes the way they estimate time.(cont.) Together, these results demonstrate that the metaphorical language people use to describe abstract phenomena provides a window on their underlying mental representations, and also shapes those representations. The structure of abstract domains such as time appears to depend, in part, on both linguistic experience and on physical experience in perception and motor action.by Daniel J. Casasanto.Ph.D

The QWERTY Effect: How typing shapes the meanings of words.

The QWERTY keyboard mediates communication for millions of language users. Here, we investigated whether differences in the way words are typed correspond to differences in their meanings. Some words are spelled with more letters on the right side of the keyboard and others with more letters on the left. In three experiments, we tested whether asymmetries in the way people interact with keys on the right and left of the keyboard influence their evaluations of the emotional valence of the words. We found the predicted relationship between emotional valence and QWERTY key position across three languages (English, Spanish, and Dutch). Words with more right-side letters were rated as more positive in valence, on average, than words with more left-side letters: the QWERTY effect. This effect was strongest in new words coined after QWERTY was invented and was also found in pseudowords. Although these data are correlational, the discovery of a similar pattern across languages, which was strongest in neologisms, suggests that the QWERTY keyboard is shaping the meanings of words as people filter language through their fingers. Widespread typing introduces a new mechanism by which semantic changes in language can arise

Functional MRI and the Wada test provide complementary information for predicting post-operative seizure control

AbstractPrediction of post-surgical seizure relief and potential cognitive deficits secondary to anterior temporal lobectomy (ATL) are important to pre-surgical planning. Although the intracarotid amobarbital test (IAT) is predictive of post-ATL seizure outcome, development of non-invasive and more precise means for determining post-ATL seizure relief are needed. We previously reported on a technique utilizing functional MRI (fMRI) to evaluate the relative functional adequacy of mesial temporal lobe structures in preparation for ATL . In the present study, we report follow-up outcome data on eight temporal lobe epilepsy (TLE) patients 1-year post-ATL who were evaluated pre-surgically using IAT and fMRI. Functional memory lateralization using fMRI predicted post-ATL seizure outcome as effectively as the IAT. In general, asymmetry of functional mTL activation favouring the non-epileptic hemisphere was associated with seizure-free status at 1-year follow-up. Moreover, when combined, fMRI and IAT provided complementary data that resulted in improved prediction of post-operative seizure control compared with either procedure alone

Motivation and Motor Control: Hemispheric Specialization for Approach Motivation Reverses with Handedness

(SSH), according to which the hemispheric laterality of affective motivation depends on the laterality of motor control for the dominant hand (i.e., the “sword hand," used preferentially to perform approach actions) and the nondominant hand (i.e., the “shield hand," used preferentially to perform avoidance actions).To determine whether the laterality of approach motivation varies with handedness, we measured alpha-band power (an inverse index of neural activity) in right- and left-handers during resting-state electroencephalography and analyzed hemispheric alpha-power asymmetries as a function of the participants' trait approach motivational tendencies. Stronger approach motivation was associated with more left-hemisphere activity in right-handers, but with more right-hemisphere activity in left-handers.The hemispheric correlates of approach motivation reversed between right- and left-handers, consistent with the way they typically use their dominant and nondominant hands to perform approach and avoidance actions. In both right- and left-handers, approach motivation was lateralized to the same hemisphere that controls the dominant hand. This covariation between neural systems for action and emotion provides initial support for the SSH

Structural Integration in Language and Music: Evidence for a Shared System.

In this study, we investigate whether language and music share cognitive resources for structural processing. We report an experiment that used sung materials and manipulated linguistic complexity (subject-extracted relative clauses, object-extracted relative clauses) and musical complexity (in-key critical note, out-of-key critical note, auditory anomaly on the critical note involving a loudness increase). The auditory-anomaly manipulation was included in order to test whether the difference between in-key and out-of-key conditions might be due to any salient, unexpected acoustic event. The critical dependent measure involved comprehension accuracies to questions about the propositional content of the sentences asked at the end of each trial. The results revealed an interaction between linguistic and musical complexity such that the difference between the subject- and object-extracted relative clause conditions was larger in the out-of-key condition than in the in-key and auditory-anomaly conditions. These results provide evidence for an overlap in structural processing between language and music

Hemispheric Specialization During Episodic Memory Encoding in the Human Hippocampus and MTL

Hemispheric specialization during episodic memory encoding was examined using three functional magnetic resonance imaging (fMRI) tasks. Stimuli for the three tasks differed in the degree to which they elicited subjects use of verbal and imagebased encoding strategies. Intentional encoding of visually presented scenes, sentences, and faces was associated with neural activity in the hippocampus and surrounding mesial Temporal Lobe (mTL) structures. Across tasks, materialspecific lateralization of neural activity was observed in the posterior mTL. In contrast, hippocampal activation did not lateralize according to material type for two of the three tasks. These results suggest a functional dissociation between the hippocampus and other mTL subcomponents, and indicate that material-specificity may not fully explain hemispheric specialization in the mTL memory system