The current study investigates how speakers are affected by thesize of the visual domain during reference production. Previousresearch found that speech onset times increase along with thenumber of distractors that are visible, at least when speakersrefer to non-salient target objects in simplified visual domains.This suggests that in the case of more distractors, speakers needmore time to perform an object-by-object scan of all distractorsthat are visible. We present the results of a reference productionexperiment, to study if this pattern for speech onset times holdsfor photo-realistic scenes, and to test if the suggested viewingstrategy is reflected directly in speakers’ eye movements. Ourresults show that this is indeed the case: we find (1) that speechonset times increase linearly as more distractors are present; (2)that speakers fixate the target relatively less often in larger do-mains; and (3) that larger domains elicit more fixation switchesback and forth between the target and its distractors.

When referring to a target object in a visual scene, speakers areassumed to consider certain distractor objects that are visible tobe more relevant than others. However, previous research thathas tested this assumption has mainly applied offline measuresof visual attention, such as the occurrence of overspecificationin speakers’ target descriptions. Therefore, in the current study,we take both online (eye-tracking) and offline (overspecifica-tion) measures of attention, to study how perceptual groupingaffects scene perception, and reference production. We manip-ulated three grouping principles: region of space, type similar-ity, and color similarity. For all three factors, we found effects,either on eye movements (region of space), overspecification(color similarity), or both (type similarity). The results for typesimilarity provide direct evidence for the close link betweenscene perception and reference production.

In this pre-registered study, we examined how non-verbal uncertainty cues, namely intonation and facial expressions, influence perceived speaker certainty and the interpretation of verbal probability phrases (e.g., "almost never," "probably," "certain"). Prior research on such phrases has focused on written cues, whereas communication often includes auditory and visual signals. Using a 2x2 within-subjects experimental design (N=100), we found that rising intonation and marked facial expressions independently reduced perceived speaker certainty. In most, but not all conditions, these cues led to greater variability in how participants assigned numerical values to verbal probability expressions (e.g., interpreting "likely" as anywhere from 10% to 85% likely). Notably, the combination of rising intonation and marked facial expressions produced the lowest perceived certainty, while there was no such additive effect on interpretation variability. These results highlight the importance of non-verbal cues in uncertainty communication, with implications for fields such as health, environmental, and technological risk communication.

Speakers often produce definite referring expressions that areoverspecified: they tend to include more attributes than neces-sary to distinguish the target referent. The current paper inves-tigates how the occurrence of overspecification is affected byviewing time. We conducted an experiment in which speakerswere asked to refer to target objects in visual domains. Half ofthe speakers had unlimited time to inspect the domains, whileviewing time was limited (1000 ms) for the other half. The re-sults reveal that limited viewing time induces the occurrenceof overspecification. We conjecture that limited viewing timecaused speakers to rely heavily on quick heuristics during at-tribute selection, which urge them to select attributes that areperceptually salient. In the case of unlimited inspection time,speakers seem to rely on a combination of heuristic and moredeliberate selection strategies.