Question: Their approaches are informed by what?
Evidence: Our lexical semantic analysis involves quantifying linguistic correlates of component psychological processes that contribute to dehumanization. Our approaches are informed by social psychology research on dehumanization, which is briefly summarized here. Prior work has identified numerous related processes that comprise dehumanization BIBREF4. One such component is likening members of the target group to non-human entities, such as machines or animals BIBREF4, BIBREF11, BIBREF12. By perceiving members of a target group to be non-human, they are “outside the boundary in which moral values, rules, and considerations of fairness apply" BIBREF13, which thus leads to violence and other forms of abuse. Metaphors and imagery relating target groups to vermin are particularly insidious and played a prominent role in the genocide of Jews in Nazi Germany and Tutsis in Rwanda BIBREF14. More recently, the vermin metaphor has been invoked by the media to discuss terrorists and political leaders of majority-Muslim countries after September 11 BIBREF15. According to BIBREF16, the vermin metaphor is particularly powerful because it conceptualizes the target group as “engaged in threatening behavior, but devoid of thought or emotional desire".
Disgust underlies the dehumanizing nature of these metaphors and is itself another important element of dehumanization. Disgust contributes to members of target groups being perceived as less-than-human and of negative social value BIBREF17. It is often evoked (both in real life and experimental settings) through likening a target group to animals. BIBREF18 find that priming participants to feel disgust facilitates “moral exclusion of out-groups". Experiments by BIBREF17 and BIBREF19 similarly find that disgust is a predictor of dehumanizing perceptions of a target group. Both moral disgust towards a particular social group and the invocation of non-human metaphors are facilitated by essentialist beliefs about groups, which BIBREF4 presents as a necessary component of dehumanization. In order to distinguish between human and non-human, dehumanization requires an exaggerated perception of intergroup differences. Essentialist thinking thus contributes to dehumanization by leading to the perception of social groups as categorically distinct, which in turn emphasizes intergroup differences BIBREF4
According to BIBREF4, much of the prior research describes “extremely negative evaluations of others" as a major component of dehumanization. This is especially pronounced in BIBREF20's account of delegitimization, which involves using negative characteristics to categorize groups that are “excluded from the realm of acceptable norms and values" BIBREF20. While BIBREF20 defines delegitimization as a distinct process, he considers dehumanization to be one means of delegitimization. BIBREF13 also discusses broader processes of moral exclusion, one of which is dehumanization. A closely related process is psychological distancing, in which one perceives others to be objects or nonexistent BIBREF13. BIBREF21 identifies elements that contribute to the objectification (and thus dehumanization) of women, one of which is denial of subjectivity, or the habitual neglect of one's experiences, emotions, and feelings.
Another component of dehumanization is the denial of agency to members of the target group BIBREF4. According to BIBREF16, there are three types of agency: "the ability to (1) experience emotion and feel pain (affective mental states), (2) act and produce an effect on their environment (behavioral potential), and (3) think and hold beliefs (cognitive mental states) BIBREF16. Dehumanization typically involves the denial of one or more of these types of agency BIBREF16.
In Section SECREF4, we introduce computational linguistic methods to quantify several of these components of dehumanization.
In Section SECREF1, we briefly discussed multiple elements of dehumanization that have been identified in social psychology literature. Here we introduce and quantify lexical correlates to operationalize four of these components: negative evaluations of a target group, denial of agency, moral disgust, and use of non-human metaphors (particularly vermin).
One prominent aspect of dehumanization is extremely negative evaluations of members of a target group BIBREF4. Attribution of negative characteristics to members of a target group in order to exclude that group from “the realm of acceptable norms and values" is specifically the key component of delegitimization, a process of moral exclusion closely related to dehumanization. We hypothesize that this negative evaluation of a target group can be realized by words and phrases whose connotations have extremely low valence, where the valence of a word refers to the dimension of meaning corresponding to positive/negative (or pleasure/displeasure) BIBREF55, BIBREF56. Thus, we propose several valence lexicon-based approaches to measure this component: paragraph-level valence analysis, Connotation Frames, and word embedding neighbor valence. Each of these techniques has different advantages and disadvantages regarding precision and interpretability.
As we mentioned above, one important dimension of affective meaning is valence, which corresponds to an individual's evaluation of an event or concept, ranging from negative/unpleasant to positive/pleasant BIBREF55, BIBREF57. A straightforward lexical approach to quantify negative evaluations of a target group is thus to measure the average valence over all words in corpora containing discussions of the target group. We quantify this by using the valence dimension from the NRC VAD lexicon, which contains real-valued scores ranging from zero to one for valence, arousal and dominance for 20,000 English words, where a score of zero is the lowest valence (most negative emotion) and a score of one is the highest possible valence (most positive emotion) BIBREF56. Words with the highest valence in the NRC VAD Lexicon include love, happy, and happily, while words with the lowest valence include toxic, nightmare, and shit.
In our case study, we qualitatively found that paragraphs were the optimal level of context for analysis; full articles often focused on topics unrelated to LGBTQ communities, even if an LGBTQ label was mentioned somewhere in the article, while single sentences did not provide enough discussion to get a sense of how LGBTQ groups are represented by the newspaper. Thus, we calculate paragraph-level scores by taking the average valence score over all words in the paragraph that appear (or whose lemmas appear) in the NRC VAD lexicon.
While paragraph-level valence analysis is quick and simple, it is sometimes too coarse because we aim to understand the sentiment directed towards the target group, not just nearby in the text. For example, suppose the target group is named “B". A sentence such as “A violently attacked B" would likely have extremely negative valence, but the writer may not feel negatively towards the victim, “B".
We address this by using BIBREF22's Connotation Frames Lexicon, which contains rich annotations for 900 English verbs (BIBREF22). Among other things, for each verb, the Connotation Frames Lexicon provides scores (ranging from -0.87 to 0.8) for the writer's perspective towards the verb's subject and object. In the example above for the verb attack, the lexicon lists the writer's perspective towards the subject “A", the attacker, as -0.6 (strongly negative) and the object “B" as 0.23 (weakly positive).
We extract all subject-verb-object tuples containing at least one target group label using the Spacy dependency parser . For each subject and object, we capture the noun and the modifying adjectives, as group labels (such as gay) can often take either nominal or adjectival forms. For each tuple, we use the connotation frame lexicon to determine the writer's perspective either towards the subject if the group label appears in the subject noun phrase, or perspective towards the object if the label appears in the object noun phrase. We then average perspective scores over all tuples.
While a Connotation Frames approach can be more precise than word-counting valence analysis, it limits us to analyzing SVO triples, which excludes a large portion of the available data about the target groups. This reveals a conundrum: broader context can provide valuable insights into the implicit evaluations of a social group, but we also want to directly probe attitudes towards the group itself.
We address this tension by training vector space models to represent the data, in which each unique word in a large corpus is represented by a vector (embedding) in high-dimensional space. The geometry of the resulting vector space captures many semantic relations between words. Furthermore, prior work has shown that vector space models trained on corpora from different time periods can capture semantic change BIBREF58, BIBREF59. For example, diachronic word embeddings reveal that the word gay meant “cheerful" or “dapper" in the early 20th century, but shifted to its current meaning of sexual orientation by the 1970s. Because word embeddings are created from real-world data, they contain real-world biases. For example, BIBREF37 demonstrated that gender stereotypes are deeply ingrained in these systems. Though problematic for the widespread use of these models in computational systems, these revealed biases indicate that word embeddings can actually be used to identify stereotypes about social groups and understand how they change over time BIBREF24.
This technique can similarly be applied to understand how a social group is negatively evaluated within a large text corpus. If the vector corresponding to a social group label is located in the semantic embedding space near negative words or terms with clearly negative evaluations, that group is likely negatively evaluated (and possibly dehumanized) in the text. These vector space models can be used in a diachronic study to capture subtle changes in the connotations of a group label over time, even when the denotational meaning of the label has remained constant. Furthermore, comparing differences in what words are most closely associated with related group labels can reveal meaning variation between these labels, even if they refer to similar populations.
We first preprocess the data by lowercasing, removing numbers, and removing punctuation. We then use the word2vec skip-gram model to create word embeddings BIBREF60. The resulting vector spaces have 100 dimensions, and we specify the following additional parameters to the model: context window of size 10, minimum frequency of 5 for a word to be included, 10 negative samples, 10 iterations, and a sampling rate of $10^{-4}$. We then use cosine similarity to determine a group label's nearest neighbors in the vector space. For our diachronic analysis, we first train word2vec on the entire corpus, and then use the resulting vectors to initialize word2vec models for each year of data in order to encourage coherence and stability across years. After training word2vec, we zero-center and normalize all embeddings to alleviate the hubness problem BIBREF61.
We then identify vectors for group labels by taking the centroid of all morphological forms of the label, weighted by frequency. For example, the vector representation for the label gay is actually the weighted centroid of the words gay and gays. This enables us to simultaneously account for adjectival, singular nominal, and plural nominal forms for each social group label with a single vector. Finally, we estimate the valence for each group label by identifying its 1000 nearest neighbors via cosine similarity (1000 was chosen arbitrarily), and calculating the average valence of all neighbors that appear in the NRC VAD valence lexicon.
We also tried using a group label's vector representation to induce a valence score directly, instead of using nearest neighbors as a proxy, by adapting the regression-based sentiment prediction from BIBREF62 for word embeddings. We found that this approach yielded similar results as analyzing nearest neighbor valence but was difficult to qualitatively interpret. More details for and results from this technique can be found in the Appendix.
Denial of agency refers to the lack of attributing a target group member with the ability to control their own actions or decisions BIBREF16. Automatically detecting the extent to which a writer attributes cognitive abilities to a target group member is an extraordinarily challenging computational task. Fortunately, the same lexicons used to operationalize negative evaluations provide resources for measuring lexical signals of denial of agency.
As in Section SECREF6, we use Connotation Frames to quantify the amount of agency attributed to a target group. We use BIBREF25's extension of Connotation Frames for agency BIBREF25. Following BIBREF25's interpretation, entities with high agency exert a high degree of control over their own decisions and are active decision-makers, while entities with low agency are more passive BIBREF25. This contrast is particularly apparent in example sentences such as X searched for Y and X waited for Y, where the verb searched gives X high agency and waited gives X low agency BIBREF25. Additionally, BIBREF25's released lexicon for agency indicates that the subjects of verbs such as attack and praise are given high agency, while the subjects of doubts, needs, and owes are given low agency BIBREF25.
This lexicon considers the agency attributed to subjects of nearly 2000 transitive and intransitive verbs. To use this lexicon to quantify denial of agency in our corpus, we extract all sentences' head verbs and their corresponding subjects, where the subject noun phrase contains a target group label. Unlike BIBREF22's real-valued Connotation Frames lexicon for perspective, the agency lexicon only provides binary labels, so we calculate the fraction of subject-verb pairs where a subject containing a group label was given high agency by its head verb.
The NRC VAD lexicon's dominance annotations provide another resource for quantifying dehumanization BIBREF56. As with valence, the NRC VAD lexicon's dominance dimension contains real-valued scores between zero and one for 20,000 English words. However, it is important to note that the dominance lexicon primarily captures power, which is distinct from but closely related to agency. While power refers to one's control over others, agency refers to one's control over their own self. While this lexicon is a proxy, it qualitatively appears to capture signals of denial of agency; the highest dominance words are powerful, leadership, success, and govern, while the lowest dominance words are weak, frail, empty, and penniless. We thus take the same approach as in Section SECREF10 with the same vector space models. However, we now calculate the average dominance score of the 1000 nearest neighbors to each group label vector representation.
As in Section SECREF10, we also induced a dominance score directly from a group label's vector representation by adapting the regression-based sentiment prediction from BIBREF62 for word embeddings. More details and results for this technique can be found in the Appendix.
In order to operationalize the moral disgust component of dehumanization with lexical techniques, we draw inspiration from Moral Foundations theory, which postulates that there are five dimensions of moral intuitions: care, fairness/proportionality, loyalty/ingroup, authority/respect, and sanctity/purity BIBREF63. The negative end of the sanctity/purity dimension corresponds to moral disgust. While we do not directly incorporate Moral Foundations Theory in our framework for dehumanization, we utilize lexicons created by BIBREF64 corresponding to each moral foundation. The dictionary for moral disgust includes over thirty words and stems, including disgust*, sin, pervert, and obscen* (the asterisks indicate that the dictionary includes all words containing the preceding prefix, such as both obscene and obscenity).
We opt for a vector approach instead of counting raw frequencies of moral disgust-related words because words that explicitly invoke moral disgust are very sparse in our news corpus. Furthermore, vectors are capable of capturing associations with the social group label itself, while counts in paragraphs and full news articles would not directly capture such associations. Using the word embeddings from Section SECREF10, we construct a vector to represent the concept of moral disgust, which is the average of the corresponding vectors for all words in the “Moral Disgust" dictionary, weighted by word frequency. This method of creating a vector from the Moral Foundations dictionary resembles that used by BIBREF65. We can then analyze implicit associations between a social group and moral disgust by calculating the cosine similarity between the group label's vector and the Moral Disgust concept vector, where a higher similarity suggests closer associations between the social group and moral disgust. As previously, each group label's vector is the average of its morphological variants' vectors, weighted by frequency.
Metaphors comparing humans to vermin have been especially prominent in dehumanizing groups throughout history BIBREF4, BIBREF15. Even if a marginalized social group is not directly equated to vermin in the press, this metaphor may be invoked in more subtle ways, such as through the use of verbs that are also associated with vermin (like scurry as opposed to the more neutral hurry) BIBREF66. While there is some natural language processing work on the complex task of metaphor detection (e.g. BIBREF67, BIBREF67), such systems would not be able to easily quantify such indirect associations.
We thus quantify the metaphorical relationship between a social group and vermin by calculating similarities between these concepts in a distributional semantic vector space, as we did with moral disgust in Section SECREF14. We create a Vermin concept vector by calculating the average of the following vermin words' vectors, weighted by frequency: vermin, rodent(s), rat(s) mice, cockroaches, termite(s), bedbug(s), fleas . We do not include the singular mouse or flea because non-vermin senses of those words were more frequent (computer mouse and flea market, respectively), and word2vec does not account for polysemy. We calculate cosine similarity between each social group label and the Vermin concept vector. A large cosine similarity between a label and the Vermin vector suggests that the social group is closely associated with vermin.
Table TABREF18 provides an overview of the four elements of dehumanization that we study and the lexical techniques used to quantify them.
Our approaches are informed by social psychology research on dehumanization, which is briefly summarized here.
Answer: Social psychology research on dehumanization.