Anya K. Bershad’s scientific contributions

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Publications (3)


The content and structure of dreams are coupled to affect
  • Article

September 2024

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15 Reads

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Anya K. Bershad

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Jes Heppler

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[...]

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Jacob G. Foster

Dreams offer a unique window into the cognitive and affective dynamics of the sleeping and the waking mind. Recent quantitative linguistic approaches have shown promise in obtaining corpus-level measures of dream sentiment and topic occurrence. However, it is currently unclear how the affective content of individual dreams relates to their semantic content and structure. Here, we combine word embedding, topic modeling, and network analysis to investigate this relationship. By applying Discourse Atom Topic Modeling (DATM) to the DreamBank corpus of 18K dream reports, we represent the latent themes arising within dreams as a sparse dictionary of topics and identify the affective associations of those topics. We show that variation in dream affect (valence and arousal) is associated with changes in topical content. By representing each dream report as a network of topics, we demonstrate that the affective content of dreams is also coupled to semantic structure. Specifically, positively valenced dreams exhibit more coherent, structured, and linear narratives, whilst negatively valenced dreams have more narrative loops and dominant topics. Additionally, topic networks of high arousal dreams are structurally dominated by few high arousal topics and incoherent topical connections, whereas low arousal dreams contain more loops. These findings suggest that affective processes are associated with both the content and structure of dreams. Our approach showcases the potential of integrating natural language processing and network analysis with psychology to elucidate the interplay of affect, cognition and narrative in dreams. This methodology has broad applications for the study of narrated experience and psychiatric symptomatology.


The content and structure of dreams are coupled to affect

September 2024

·

35 Reads

Dreams offer a unique window into the cognitive and affective dynamics of the sleeping and the waking mind. Recent quantitative linguistic approaches have shown promise in obtaining corpus-level measures of dream sentiment and topic occurrence. However, it is currently unclear how the affective content of individual dreams relates to their semantic content and structure. Here, we combine word embedding, topic modeling, and network analysis to investigate this relationship. By applying Discourse Atom Topic Modeling (DATM) to the DreamBank corpus of >18K dream reports, we represent the latent themes arising within dreams as a sparse dictionary of topics and identify the affective associations of those topics. We show that variation in dream affect (valence and arousal) is associated with changes in topical content. By representing each dream report as a network of topics, we demonstrate that the affective content of dreams is also coupled to semantic structure. Specifically, positively valenced dreams exhibit more coherent, structured, and linear narratives, whilst negatively valenced dreams have more narrative loops and dominant topics. Additionally, topic networks of high arousal dreams are structurally dominated by few high arousal topics and incoherent topical connections, whereas low arousal dreams contain more loops. These findings suggest that affective processes are associated with both the content and structure of dreams. Our approach showcases the potential of integrating natural language processing and network analysis with psychology to elucidate the interplay of affect, cognition and narrative in dreams. This methodology has broad applications for the study of narrated experience and psychiatric symptomatology.


Figure 1. A: Top: Scatterplot of valence and arousal for the 130 topics modeled over the DreamBank dataset, coloured by topic prevalence. Prevalence denotes the proportion of narratives in which a topic occurs. More blue points indicate that a topic occurs with lower prevalence and more red, greater. There is no significant correlation between topic valence and arousal (fit: black line; Pearson correlation: r=-0.11, p=0.19). Bottom: kernel density map of narratives (n=18622) over the dimensions of median dream valence and arousal. The x-axis was divided into 30 hexagonal bins. Dream report valence and arousal were negatively correlated (fit: black line; Pearson's r=-0.33, p<0.001). B: Heatmaps comparing the prevalence of topics in dream reports in the top and bottom quartiles for valence (left two columns) and for arousal (right two columns). Each horizontal bar represents one topic. C: Topic key showing the three topics occurring with greatest divergence in prevalence between top and bottom quartiles for valence (top six rows) or arousal (bottom six rows), ranked by their divergence. The six most representative words for each topic, with the highest cosine similarity to that topic, are shown. Coloured values in bold indicate greater relative prevalence in the corresponding quartile (yellow: top quartile valence; purple: bottom quartile valence; red: top quartile arousal; blue: bottom quartile arousal).
Figure 2. A: Example highly negative dream report with topic network. Corresponding topics are placed over their inferred location in the report. The most representative word for each topic is highlighted in bold. Topic numbers and colors correspond to nodes (circles) in the topic network (right), with directed edges (arrows) connecting successive topics. For further examples of annotated dream networks see Appendix. B: Characterisation of dream topic networks. Top left: distribution of topic frequency against topic degree (number of connections) over all dream topic networks (n=18622). Insert shows a large topic network, which illustrates the scale-free nature of dream networks (see Appendix for full dream narrative). Nodes are coloured by valence (more positive, more yellow; more negative, more purple) and the size of nodes in networks is proportional to their overall degree. Edge lengths are proportional to the distance between connected topics in our embedding (more semantically similar topics are connected by shorter edges). Bottom left: histogram of log topic degree, divided into 20 bins, against log topic frequency with fit over topics with degree≥2 (slope=-4.42). Middle column: mean valence of neighboring topics against topic valence (top) or mean arousal of neighboring topics against topic arousal (bottom). Each point represents a unique topic (n=130), coloured by their valence (more negative topics are more purple and more
Figure 3. Dream report topic network analysis for valence (left column) and arousal (right column). A: Partial-least squares regression (PLS) on network properties against valence and arousal over all analyzed topic networks (n=18622). More positive (valence: yellow; arousal: red) PLS coefficients indicate a property to be more positively associated with an affective dimension, whilst more negative (valence: purple; arousal: blue) coefficients indicate a property to be more negatively associated with an affective dimension. Statistical significance of coefficients was obtained via permutation tests (permutations=1000) and is indicated by asterisks (* p<0.05, ** p<0.01, *** p<0.001). Inserts of networks illustrate the associated network change. Higher valence topic networks (yellow) are more modular and linear, whilst more negative networks (purple) have more loops (feedback loops (n.s.), clustering and transitivity) and more dominant hubs (degree heterogeneity and Gini). Higher arousal topic networks (red) are larger and have more dominant hubs, whereas lower arousal topic networks (blue) have more loops. B: Prevalence of each of the 130 topics in our dataset against their mean degree, averaged over narratives in the top quartile (top row) or the bottom quartile (bottom row) for valence (left) and arousal (right). Solid black lines indicate back-transformed LMM fits. Left: Higher valence topics are more yellow and lower, more purple. Right: Higher arousal topics are more red and lower, more blue. Note the horizontal dashed lines in the graphs for networks of the bottom valence quartile and top arousal quartile. These correspond to the maximum measured mean degree measured for a topic in the datasets of the top quartile of valence and bottom quartile of arousal, respectively.
Figure S1. Measures of topic diversity, coherence and R 2 for DATM topic models ranging in size from 15 to 305 topics, which we used to determine our final model size. Our selected model, with 130 topics, is highlighted in bold.
Figure S2. Matrices of final PLS coefficients for the effect of our tested network properties on valence (left) and arousal (right) at different topic model sizes. -indicates a negative PLS coefficient (valence: more purple; arousal: more blue) and + indicates a positive coefficient (valence: more yellow; arousal: more red). +/-operators in bold indicate significant coefficients (p<0.05), as determined by a permutation test.

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The content and structure of dreams are coupled to affect
  • Preprint
  • File available

September 2024

·

128 Reads

Dreams offer a unique window into the cognitive and affective dynamics of the sleeping and the waking mind. Recent quantitative linguistic approaches have shown promise in obtaining corpus-level measures of dream sentiment and topic occurrence. However, it is currently unclear how the affective content of individual dreams relates to their semantic content and structure. Here, we combine word embedding, topic modeling, and network analysis to investigate this relationship. By applying Discourse Atom Topic Modeling (DATM) to the DreamBank corpus of >18K dream reports, we represent the latent themes arising within dreams as a sparse dictionary of topics and identify the affective associations of those topics. We show that variation in dream affect (valence and arousal) is associated with changes in topical content. By representing each dream report as a network of topics, we demonstrate that the affective content of dreams is also coupled to semantic structure. Specifically, positively valenced dreams exhibit more coherent, structured, and linear narratives, whilst negatively valenced dreams have more narrative loops and dominant topics. Additionally, topic networks of high arousal dreams are structurally dominated by few high arousal topics and incoherent topical connections, whereas low arousal dreams contain more loops. These findings suggest that affective processes are associated with both the content and structure of dreams. Our approach showcases the potential of integrating natural language processing and network analysis with psychology to elucidate the interplay of affect, cognition and narrative in dreams. This methodology has broad applications for the study of narrated experience and psychiatric symptomatology.

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