While speculations on form–meaning resemblances in language go back millennia, the experimental study of iconicity is only about a century old. Here we take stock of experimental work on iconicity and present a double special issue with a diverse set of new contributions. We contextualise the work by introducing a typology of approaches to iconicity in language. Some approaches construe iconicity as a discrete property that is either present or absent; others treat it as involving semiotic relationships that come in kinds; and yet others see it as a gradient substance that comes in degrees. We show the benefits and limitations that come with each of these construals and stress the importance of developing accounts that can fluently switch between them. With operationalisations of iconicity that are well defined yet flexible enough to deal with differences in tasks, modalities, and levels of analysis, experimental research on iconicity is well equipped to contribute to a comprehensive science of language.

Onomatopoeia is widespread across the world’s languages. They represent a relatively simple iconic mapping: the phonological/phonetic properties of the word evokes acoustic related features of referents. Here, we explore the EEG correlates of processing onomatopoeia in English. Participants were presented with a written cue-word (e.g., leash) and then with a spoken target-word. The target-word was either an onomatopoeia (e.g., bark), a sound-related but arbitrary word (e.g., melody), or another arbitrary word (e.g., bike). Participants judged whether the cue- and the target-word were similar in meaning. We analysed Event-Related Potentials (ERPs) in different time-windows: (i) early (100–200 and 200–250 ms) to assess differences in processing at the form-level; (ii) the N400 time-window (300–500 ms) in order to establish if there are differences in semantic processing across our word-types; and (iii) late (600–900 ms) to assess post-lexical effects. We found that onomatopoeia differed from the other words in the N400 time-window: when cue and target were unrelated, onomatopoeic words led to greater negativity which can be accounted for in terms of enhanced semantic activation of onomatopoeia which leads to greater salience of the mismatch. We discuss results in the context of a growing body of literature investigating iconicity in language processing and development.

Recent work suggests that not all aspects of learning benefit from an iconicity advantage (Ortega, 2017). We present the results of an artificial sign language learning experiment testing the hypothesis that iconicity may help learners to learn mappings between forms and meanings, whilst having a negative impact on learning specific features of the form. We used a 3D camera (Microsoft Kinect) to capture participants’ gestures and quantify the accuracy with which they reproduce the target gestures in two conditions. In the iconic condition, participants were shown an artificial sign language consisting of congruent gesture–meaning pairs. In the arbitrary condition, the language consisted of non-congruent gesture–meaning pairs. We quantified the accuracy of participants’ gestures using dynamic time warping (Celebi et. al., 2013). Our results show that participants in the iconic condition learn mappings more successfully than participants in the arbitrary condition, but there is no difference in the accuracy with which participants reproduce the forms. While our work confirms that iconicity helps to establish form–meaning mappings, our study did not give conclusive evidence about the effect of iconicity on production; we suggest that iconicity may only have an impact on learning forms when these are complex.

This paper investigates the underlying cognitive processes of sound–color associations by connecting perceptual evidence from research on cross-modal correspondences to sound symbolic patterns in the words for colors in natural languages. Building upon earlier perceptual experiments, we hypothesized that sonorous and bright phonemes would be over-represented in the words for bright and saturated colors. This hypothesis was tested on eleven color words and related concepts (red–green, yellow–blue, black–white, gray, night–day, dark–light) from 245 language families. Textual data was transcribed into the International Phonetic Alphabet (IPA), and each phoneme was described acoustically using high-quality IPA recordings. These acoustic measurements were then correlated with the luminance and saturation of each color obtained from cross-linguistic color-naming data in the World Color Survey. As expected, vowels with high brightness and sonority ratings were over-represented in the words for colors with high luminance, while sonorous consonants were more common in the words for saturated colors. We discuss these results in relation to lexicalization patterns and the links between iconicity and perceptual cross-modal associations.

In this study we explore whether different types of iconic gestures (i.e., acting, drawing, representing) and their combinations are used systematically to distinguish between different semantic categories in production and comprehension. In Study 1, we elicited silent gestures from Mexican and Dutch participants to represent concepts from three semantic categories: actions, manipulable objects, and non-manipulable objects. Both groups favoured the acting strategy to represent actions and manipulable objects; while non-manipulable objects were represented through the drawing strategy. Actions elicited primarily single gestures whereas objects elicited combinations of different types of iconic gestures as well as pointing. In Study 2, a different group of participants were shown gestures from Study 1 and were asked to guess their meaning. Single-gesture depictions for actions were more accurately guessed than for objects. Objects represented through two-gesture combinations (e.g., acting + drawing) were more accurately guessed than objects represented with a single gesture. We suggest iconicity is exploited to make direct links with a referent, but when it lends itself to ambiguity, individuals resort to combinatorial structures to clarify the intended referent. Iconicity and the need to communicate a clear signal shape the structure of silent gestures and this in turn supports comprehension.

Iconicity has traditionally been considered an objective, fixed, unidimensional property of language forms, often operationalized as transparency for experimental purposes. Within a Cognitive Linguistics framework, iconicity is a mapping between an individual’s construal of form and construal of meaning, such that iconicity is subjective, dynamic, and multidimensional. We test the latter alternative by asking signers who differed in ASL proficiency to complete a handshape monitoring task in which we manipulated the number of form–meaning construals that target handshapes participated in. We estimated the interaction of iconicity, proficiency, and construal density using mixed-effects models for response time and accuracy with crossed random effects for participants and items.

Results show a significant three-way interaction between iconicity, proficiency, and construal density such that less-proficient signers detected handshapes in more iconic signs faster than less iconic signs regardless of the handshape they were monitoring, but highly proficient signers’ performance was only improved by iconicity for handshapes that participate in many construals. Taken in conjunction with growing evidence of the subjectivity of iconicity, we interpret these results as support for the claim that construal is a core mechanism underlying iconicity, both for transparent and systematic language-internal form–meaning mappings.

Reaction times for a translation recognition study are reported where novice to expert English–ASL bilinguals rejected English translation distractors for ASL signs that were related to the correct translations through phonology, semantics, or both form and meaning (diagrammatic iconicity). Imageability ratings of concepts impacted performance in all conditions; when imageability was high, participants showed interference for phonologically related distractors, and when imageability was low participants showed interference for semantically related distractors, regardless of proficiency. For diagrammatically related distractors high imageability caused interference in experts, but low imageability caused interference in novices. These patterns suggest that imageability and diagrammaticity interact with proficiency – experts process diagrammatic related distractors phonologically, but novices process them semantically. This implies that motivated signs are dependent on the entrenchment of language systematicity; rather than decreasing their impact on language processing as proficiency grows, they build on the original benefit conferred by iconic mappings.

In contrast to arbitrariness, a recent perspective is that words contain both arbitrary and iconic aspects. We investigated iconicity in word recognition, and the possibility that iconic words have special links between phonological and semantic features that may facilitate their processing. In Experiment 1, participants completed a lexical decision task (“Is this letter string a word?”) including words varying in their iconicity. Notably, we manipulated stimulus presentation conditions such that the items were visually degraded for half of the participants; this manipulation has been shown to increase reliance on phonology. Responses to words higher in iconicity were faster and more accurate, but this did not interact with condition. In Experiment 2 we explicitly directed participants’ attention to phonology by using a phonological lexical decision task (“Does this letter string sound like a word?”). Responses to words that were higher in iconicity were once again faster. These results demonstrate facilitatory effects of iconicity in lexical processing, thus showing that the benefits of iconic mappings extend beyond those reported for language learning and those argued for language evolution.

A growing body of research shows that both signed and spoken languages display regular patterns of iconicity in their vocabularies. We compared iconicity in the lexicons of American Sign Language (ASL) and English by combining previously collected ratings of ASL signs (Caselli, Sevcikova Sehyr, Cohen-Goldberg, & Emmorey, 2017) and English words (Winter, Perlman, Perry, & Lupyan, 2017) with the use of data-driven semantic vectors derived from English. Our analyses show that models of spoken language lexical semantics drawn from large text corpora can be useful for predicting the iconicity of signs as well as words. Compared to English, ASL has a greater number of regions of semantic space with concentrations of highly iconic vocabulary. There was an overall negative relationship between semantic density and the iconicity of both English words and ASL signs. This negative relationship disappeared for highly iconic signs, suggesting that iconic forms may be more easily discriminable in ASL than in English. Our findings contribute to an increasingly detailed picture of how iconicity is distributed across different languages.

Words like ‘waddle’, ‘flop’, and ‘zigzag’ combine playful connotations with iconic form–meaning resemblances. Here we propose that structural markedness may be a common factor underlying perceptions of playfulness and iconicity. Using collected and estimated lexical ratings covering a total of over 70,000 English words, we assess the robustness of this association. We identify cues of phonotactic complexity that covary with funniness and iconicity ratings and that, we propose, serve as metacommunicative signals to draw attention to words as playful and performative. To assess the generalisability of the findings we develop a method to estimate lexical ratings from distributional semantics and apply it to a dataset 20 times the size of the original set of human ratings. The method can be used more generally to extend coverage of lexical ratings. We find that it reliably reproduces correlations between funniness and iconicity as well as cues of structural markedness, though it also amplifies biases present in the human ratings. Our study shows that the playful and the poetic are part of the very texture of the lexicon.