The neural and cognitive bases of ambiguous and unambiguous conceptual combination

Conceptual representations can be altered to align with the current context given learning and task goals. One cognitive process, known as conceptual combination, allows for a unique perspective for exploring how complex conceptual processing occurs and how this processing influences the underlying representations of concepts. During novel nominal conceptual combination, two constituent nouns, a modifier noun (e.g., lemon) and a head noun (e.g., flamingo) are creatively combined to form a novel meaning (e.g., a lemon flamingo might be a yellow flamingo). Different strategies can be taken up by combiners - typically being either attributive (as above) or relational (e.g., a lemon flamingo is a flamingo that consumes lemons). Importantly, few studies have directly examined more ambiguous combinations, which are more complex to process, having an equal likelihood of being combined attributively or relationally between individuals. This dissertation addresses two main aims for understanding nominal conceptual combination through a series of four studies. First, it explores the pathways driving different kinds of conceptual combination. In Study 1, I examine how easily conceptual combinations can be formed and subsequently remembered. In Study 2, I explore how individual differences in cognition predict ease of combining. The second aim explores how conceptual combination differently impacts the representations of the constituent concepts. In Study 3, I address whether and how the cognitive representations of the head noun in a conceptual combination are altered because of being conceptually combined. Finally, Study 4 addresses both aims using neuroimaging to explore how different types of conceptual combinations are processed and how the neural representations of concepts are altered because of their combination. The findings show representational change due to conceptual combination in early visual processing regions of the brain and suggest that conceptual combination may rely on additional cognitive processes throughout the lifespan. There is also an emerging theme of the importance of cognitive control in the ease of combining. Finally, the findings show differences in the processing of different types of conceptual combinations, both between attributive and relational combinations and between unambiguous and ambiguous, advocating for the inclusion of ambiguous compounds in future studies of conceptual combination

Connectivity Based on Multi-Voxel Patterns Can Selectively Identify Brain Networks Where Condition-based Functional Connectivity Does Not: Evidence from the Scene Network

With a major focus of neuroimaging research on mapping brain network connectivity, it is essential that researchers use the most effective methods for determining which regions comprise functional networks. Here, we compare the functional magnetic resonance imaging (fMRI) brain networks that can be identified through shared fluctuations in regions’ univariate responses to conditions (i.e., condition-based functional connectivity), with those identified by shared fluctuations in multivariate information. To do this, we compare brain networks generated by two approaches for measuring connectivity: psychophysiological interaction (PPI), which measures the effect of conditions on shared univariate responses, and informational connectivity (IC), which measures shared fluctuations in the discriminability of multi-voxel patterns. We compare the findings generated by applying these methods to data collected while people perceptually process scenes and control (pseudo) scenes. Prior work establishing the regions involved in scene processing give us an opportunity to compare the sensitivity and selectivity of these approaches to detect a stimulus-relevant network. We find that, while each measure produces useful information, the PPI method was less selective than IC in detecting scene-related regions. Using PPI led to identifying networks containing both scene and object regions, with little specificity in connections between scene regions. In contrast, the network identified by IC was more consistent with prior literature examining the brain’s scene network. We recommend that – for conditions known to be represented in multi-voxel patterns – researchers wishing to prioritize specificity in mapping networks should examine informational connectivity over univariate connectivity approaches such as PPI

Expertise Moderates Incidentally Learned Associations Between Words and Images

Individuals with expertise in a domain of knowledge demonstrate superior learning for information in their area of expertise, relative to non-experts. In this study, we investigated whether expertise benefits extend to learning associations between words and images that are encountered incidentally. Sport-knowledge-experts and non-sports-experts encountered previously unknown faces through a basic perceptual task. The faces were incidentally presented as candidates for a position in a sports team (a focus of knowledge for only the sports-experts) or for a job in a business (a focus of knowledge for both the sports-experts and non-sports-experts). Participants later received a series of surprise memory tests that tested: ability to recognize each face as being old, the amount of information recalled about each face, and ability to select a correct face from equally familiar alternatives. Relative to non-sports-experts, participants with superior sports expertise were able to better recall the information associated with each face and could better select associated faces from similarly familiar options for the hypothetical prospective athletes. Hypothetical job candidates were recalled and selected at similar levels of performance in both groups. The groups were similarly familiar with the images (in a yes/no recognition memory test) when the faces were prospective athletes or job candidates. These findings suggest a specific effect of expertise on associative memory between words and images, but not for individual items, supporting a dissociation in how expertise modulates the human memory system for word–image pairings