Objective: A wealth of studies provide evidence for action simulation during language comprehension. Recent research suggests such action simulations might be sensitive to finegrained information, such as speed. Here we present a crucial test for action simulation of speed in language by assessing speed comprehension in patients with Parkinson's disease (PD). Based on the patients' motor deficits, we hypothesized that the speed of motion described in language would modulate their performance in semantic tasks. Specifically, they would have more difficulty processing language about relatively fast speed than language about slow speed.
Method:We conducted a semantic similarity judgment task on fast and slow action verbs in patients with PD and age-matched healthy controls. Participants had to decide which of two verbs most closely matched a target word. Results: Compared to controls, PD patients were slower making judgments about fast action verbs, but not for judgments about slow action verbs, suggesting impairment in processing language about fast action. Moreover, this impairment was specific to verbs describing fast action performed with the hand. Conclusions:Problems moving quickly lead to difficulties comprehending language about moving quickly.This study provides evidence that speed is an important part of action representations.Keywords: embodiment; Parkinson's disease; action semantics; speed Speed -Speed Verbs in Parkinson's Disease 3 The view that meaning in language is represented in modality-specific brain regions (e.g., Binder & Desai, 2011) contrasts with proposals that meaning is stored in abstract, amodal systems (e.g., Landau & Dumais, 1997). There now exist a large number of studies demonstrating action simulation during language comprehension (for review see Fischer & Zwaan, 2008). A critical question, however, is the level of abstraction of action simulations; to what extent do they mirror real-world action? Embodied theories are underspecified in terms of how much information is contained in a simulation (Sanford, 2008), or at what grain information is represented.Action simulations include the specific effector used in the action (Hauk, Johnsrude, & Pulvermüller, 2004), or the specificity of the action . Recent research suggests even fine-grained temporal information is represented in action simulations: whether the action is fast or slow (Speed & Vigliocco, 2014;Speed & Vigliocco, 2015; van Dam, Speed, Lai, Vigliocco, & Desai, in press). Speed & Vigliocco (2014) showed online simulations are sensitive to speed: when listening to sentences describing fast and slow actions (e.g. The lion dashed to the balloon vs. The lion ambled to the balloon) looking time towards a concurrent visual scene was longer for slow actions compared to fast actions. Related, mental simulation is also sensitive to the degree of effort implied in a sentence (e.g., pushing the piano vs. pushing the chair) (Moody & Gennari, 2010).Studies of patients with motor deficits can provide strong tests of causali...