Rightward directional bias in art produced by cultures without a written language.

In this study, we coded art painted on rocks located in southern Africa, which was painted with a mixture of ochre, blood, and clay by the San, a Neolithic culture with no written language. These images depict a mixture of humans and animals in a variety of contexts, including (but not limited to) hunts and dances. We calculated a laterality index for the collected available art from each region, finding that although there was variability across regions in the direction of the laterality scores, most regions contained a majority of figures facing rightward. This is in stark contrast with reports of artists drawing leftward facing animals and human profiles (an effect that is influenced by native language writing system direction, gender, and handedness), but interestingly our sample also contained regions with strong leftward biases. Our results are, however, in accord with studies that report people preferring images that depict left-to-right motion, as well as the left-to-right bias in depicting transitive actions, an effect that seems to result from greater right hemispheric activation in scene processing and interpretation. Thus, this study shows that in the absence of a writing system, right-lateralized neural architecture may guide the hands of artists.

The N400 in processing repeated name and pronoun anaphors in sentences and discourse.

We report two EEG/ERP experiments that examined processing of repeated name (e.g., Bill; Experiment 1) and pronoun (e.g., he; Experiment 2) subject anaphors to single antecedents (e.g., Bill) and to antecedents embedded in a conjunction (e.g., Bill and Mary) within sentences and discourses. Experiment 1 replicated previous reports of repeated references to single antecedents eliciting greater N400 negativity than repeated references to conjoined antecedents within sentences, and extended these results to cross-sentence (discourse) references. Experiment 2 found that pronouns also elicited greater N400 negativity following single than conjoined antecedents. In both experiments, references to conjoined antecedents elicited greater frontal negativity than references to single antecedents in both sentences and discourse. Our results indicate that, in processing subject anaphors, the N400 is an index of reference predictability rather than a marker of the fit between antecedent salience and reference form, and that frontal negativity marks referential ambiguity elicited by conjoined phrases.

Syntax response-space biases for hands, not feet.

A number of studies have shown a relationship between comprehending transitive sentences and spatial processing (e.g., Chatterjee, Trends in Cognitive Sciences, 5(2), 55-61, 2001), in which there is an advantage for responding to images that depict the agent of an action to the left of the patient. Boiteau and Almor (Cognitive Science, 2016) demonstrated that a similar effect is found for pure linguistic information, such that after reading a sentence, identifying a word that had appeared earlier as the agent is faster on the left than on the right, but only for left-hand responses. In this study, we examined the role of lateralized manual motor processes in this effect and found that such spatial effects occur even when only the responses, but not the stimuli, have a spatial dimension. In support of the specific role of manual motor processes, we found a response-space effect with manual but not with pedal responses. Our results support an effector-specific (as opposed to an effector-general) hypothesis: Manual responses showed spatial effects compatible with those in previous research, whereas pedal responses did not. This is consistent with theoretical and empirical work arguing that the hands are generally involved with, and perhaps more sensitive to, linguistic information.

Transitivity, Space, and Hand: The Spatial Grounding of Syntax.

Previous research has linked the concept of number and other ordinal series to space via a spatially oriented mental number line. In addition, it has been shown that in visual scene recognition and production, speakers of a language with a left-to-right orthography respond faster to and tend to draw images in which the agent of an action is located to the left of the patient. In this study, we aim to bridge these two lines of research by employing a novel method that measures the spatial bias produced by transitive sentences that use a wide variety of abstract and concrete verbs. Across four experiments, participants read sentences and then responded to probe words appearing on either the left or right sides of the screen. Probe words consisted of agents, patients, other words in the sentence, or newly encountered words. We found consistent lateral biases to responding to agents and patients, which appears to be independent of order of mention in the sentence but which does reflect a correspondence between position in the sentence and role in the causal sequence of the action. Our results also show that this spatial bias is driven by the use of the hands in two different ways: The left hand shows a greater sensitivity to the spatial effect than the right hand, and vocal responses produce no spatial effect.

Bilateral parietal contributions to spatial language.

It is commonly held that language is largely lateralized to the left hemisphere in most individuals, whereas spatial processing is associated with right hemisphere regions. In recent years, a number of neuroimaging studies have yielded conflicting results regarding the role of language and spatial processing areas in processing language about space (e.g., Carpenter, Just, Keller, Eddy, & Thulborn, 1999; Damasio et al., 2001). In the present study, we used sparse scanning event-related functional magnetic resonance imaging (fMRI) to investigate the neural correlates of spatial language, that is; language used to communicate the spatial relationship of one object to another. During scanning, participants listened to sentences about object relationships that were either spatial or non-spatial in nature (color or size relationships). Sentences describing spatial relationships elicited more activation in the superior parietal lobule and precuneus bilaterally in comparison to sentences describing size or color relationships. Activation of the precuneus suggests that spatial sentences elicit spatial-mental imagery, while the activation of the SPL suggests sentences containing spatial language involve integration of two distinct sets of information - linguistic and spatial.

Semantic Relations Cause Interference in Spoken Language Comprehension When Using Repeated Definite References, Not Pronouns.

The choice and processing of referential expressions depend on the referents' status within the discourse, such that pronouns are generally preferred over full repetitive references when the referent is salient. Here we report two visual-world experiments showing that: (1) in spoken language comprehension, this preference is reflected in delayed fixations to referents mentioned after repeated definite references compared with after pronouns; (2) repeated references are processed differently than new references; (3) long-term semantic memory representations affect the processing of pronouns and repeated names differently. Overall, these results support the role of semantic discourse representation in referential processing and reveal important details about how pronouns and full repeated references are processed in the context of these representations. The results suggest the need for modifications to current theoretical accounts of reference processing such as Discourse Prominence Theory and the Informational Load Hypothesis.

The neural representation of plural discourse entities.

Little is known about the underlying neural structures that mediate the generation and tracking of discourse referents. In two functional magnetic resonance imaging experiments, we examined the neural structures involved in generating and maintaining the representations of multiple referents. Experiment 1 used two-sentence discourses with singular and plural conditions linking back to single or conjoined subjects. In Experiment 2, conjunction type was manipulated in order to keep the number of discourse entities constant across the discourse. Both experiments found greater activation in the superior parietal lobule bilaterally for plural entities relative to singular entities in Experiment 1 and for unconjoined plural entities relative to conjoined plural entities in Experiment 2. This parietal activation suggests that referring to multiple entities evokes multiple representations that need to be integrated and tracked. We discuss these findings in terms of psycholinguistic theories of multiple referent representations.

Interference between conversation and a concurrent visuomotor task.

We report 2 experiments during which participants conversed with either a confederate (Experiment 1) or a close friend (Experiment 2) while tracking a moving target on a computer screen. In both experiments, talking led to worse performance on the tracking task than listening. We attribute this finding to the increased cognitive demands of speech planning and monitoring. Growth curve analyses of task performance during the beginning and end of conversation segments revealed dynamical changes in the impact of conversation on visuomotor task performance, with increasing impact during the beginning of speaking segments and decreasing impact during the beginning of listening segments. At the end of speaking and listening segments, this pattern reversed. These changes became more pronounced with increased difficulty of the task. Together, these results show that the planning and monitoring aspects of conversation require the majority of the attentional resources that are also used for nonlinguistic visuomotor tasks. The fact that similar results were obtained when conversing with both a confederate and a friend indicates that our findings apply to a wide range of conversational situations. This is the first study to show the fine-grained time course of the shifting attentional demands of conversation on a concurrently performed visuomotor task.