When does perception facilitate or interfere with conceptual processing? The effect of attentional modulation

Conceptual processing relies on the perceptual system, and, as such, perception affects conception. Many studies have demonstrated perceptual-conceptual interference, where perceptual stimulation in a particular modality leads to slower and/or less accurate conceptual processing of information from the same modality (e.g., Kaschak et al., 2005, 2006; Vermeulen et al., 2008). However, many other studies have demonstrated perceptual-conceptual facilitation, where perceptual stimulation leads to faster and/or more accurate conceptual processing in the same modality (Kaschak et al., 2006; van Dantzig et al., 2008; Connell et al., 2012; Connell and Lynott, in preparation). At first glance, this apparent discrepancy seems like a serious problem for accounts of simulation-based concepts. Such theories hold that offline representations—that is, representations of objects and events that are not in the current environment (Wilson, 2002)—are functionally comprised of partial replays (i.e., simulations) of the neural activation captured during perceptual, motor, affective, and other experience (Barsalou, 1999, 2008; Glenberg and Gallese, 2012; Connell and Lynott, submitted). If conceptual representations therefore require modalityspecific perceptual simulation, then why do they not consistently interact with perception? Why does perceptual stimulation sometimes impair and sometimes facilitate conceptual processing? One account proposed that the difference lies in whether perceptual stimulation is concurrent with the conceptual task or precedes it, and whether or not the perceptual stimulus can be easily integrated into the simulation required by the conceptual task (Kaschak et al., 2005). According to this account, interference occurs when a concurrent perceptual stimulus cannot be integrated into the simulation required by the conceptual task. For example, Kaschak and colleagues argued that an upwardscrolling visual display could not be easily integrated with the sentence The cat climbed the tree, and hence interfered with its simulation. Facilitation occurs when a perceptual stimulus can be easily integrated into a simulation, regardless of whether the perceptual and conceptual components of the trial are presented concurrently or sequentially. For example, an image of a car would facilitate understanding a sentence like The car approached you. However, this account cannot easily explain later findings. For example, concurrent tactile stimulation, in the form of vibrations to the palms and fingers, facilitates people’s ability to judge the size of manipulable objects (Connell et al., 2012). Vibrotactile stimulation seems at least as distant from object representations of wallets and keys as upward-scrolling lines are from a cat climbing a tree. Yet, even though both perceptual stimuli appear “nonintegratible,” the former produced facilitation and the latter interference.