Riding the lexical speedway: a critical review on the time course of lexical selection in speech production

Abstract

Speech requires time. How much time often depends on the amount of labor the brain has to perform in order to retrieve the linguistic information related to the ideas we want to express. Although most psycholinguistic research in the field of language production has focused on the net result of time required to utter words in various experimental conditions, over the last years more and more researchers pursued the objective to flesh out the time course of particular stages implicated in language production. Here we critically review these studies, with particular interest for the time course of lexical selection. First, we evaluate the data underlying the estimates of an influential temporal meta-analysis on language production (Indefrey and Levelt, 2004). We conclude that those data alone are not sufficient to provide a reliable time frame of lexical selection. Next, we discuss recent neurophysiological evidence which we argue to offer more explicit insights into the time course of lexical selection. Based on this evidence we suggest that, despite the absence of a clear time frame of how long lexical selection takes, there is sufficient direct evidence to conclude that the brain initiates lexical access within 200 ms after stimulus presentation, hereby confirming Indefrey and Levelt's estimate. In a final section, we briefly review the proposed mechanisms which could lead to this rapid onset of lexical access, namely automatic spreading activation versus specific concept selection, and discuss novel data which support the notion of spreading activation, but indicate that the speed with which this principle takes effect is driven by a top-down signal in function of the intention to engage in a speech act.

Keywords: ERPs; MEG; behavioral chronometry; language production; lexical selection; review; time course.

Figure 1

Simple and schematic model of object naming.

Figure 2

Time latency representation of the LRP/N200 dual-task button-press ERP studies. (A) Traditional way latencies in this paradigm are allocated. (B) Alternative allocation of the LRP/N200 latencies when taking into account difficulty. (C) Another alternative allocation of the LRP/N200 latencies from the perspective of decision making. The arrows schematically (simplified) represent the possible amount of noise during evidence accumulation.

Figure 3

ERP data plotted for word frequency and cognate status in overt object naming. (A) Low frequency ERPs compared to high frequency ERPs in Experiment 1 at PO2 and the electrodes showing a significant effect at 172 ms after picture presentation (gray area; it does not represent the topography of the effect). (B) Non-cognate ERPs compared to cognate ERPs in Experiment 1 at PO2 and distribution of electrodes showing a significant effect at 200 ms after picture presentation (gray area). (Figure taken from Experiment 1 in Strijkers et al., 2010).

Figure 4

Event-related potential (ERP) results and correlation analyses of the CSIE. (A) ERPs elicited by the five ordinal positions within the semantic categories. The waveforms depicted are the linear derivation of the 10 posterior electrodes where significant effects were present (CP1, CP2, P3, Pz, P4, PO1, PO2, O1, Oz, O2). The dark gray area refers to the P2 peak and P3 peak showing a linear and cumulative increase in amplitude with each ordinal position. Above the topographic maps of the averaged differences waves of the five ordinal positions for the P2 and P3 are shown. The light gray area refers to the time frame (208–388 ms) where ERP amplitudes correlated with ordinal position and RTs. (B) Significance graph of the correlation analyses at each sampling rate (4 ms) between RTs and ERP amplitudes at the 5 ordinal positions for the 10 posterior electrodes. (C) Significance graph of the correlation analyses at each sampling rate (4 ms) between RTs and ERP amplitudes at the 5 ordinal positions averaged over the 10 posterior electrodes. Correlations were reliably below the 0.05 significance level (following a row of 12 consecutive significant t-test; cf. Guthrie and Buchwald, 1991) between 208 and 388 ms after picture presentation (light gray area). (Figure taken from Costa et al., 2009).

Figure 5

Event-related potential results for object naming versus object categorization. At the left hand side: ERPs elicited during object naming by pictures with low compared to those with high frequency names at Frontal (Fr) and Centro-Parietal (CP) electrode clusters. Grayed areas show significant frequency effects at the P2 and N400. At the right hand side: ERPs elicited during object categorization by pictures with low compared to those with high frequency names at Frontal (Fr) and Centro-Parietal (CP) electrode clusters. Grayed areas show significant frequency effects at the N400. (Figure taken and adapted from Experiments 1 and 2 in Strijkers et al., 2011).