Pupil-BLAH-metry: cognitive effort in speech planning reflected by pupil dilation

Abstract

In reading research, a longstanding question is whether any stages of lexical processing require central attention, and whether such potential demands are frequency-sensitive. In the present study, we examined the allocation of cognitive effort in lexical processing by examining pupil dilations and naming latencies in a modified delayed naming procedure. In this dual-task/change procedure, participants read words and waited for various delays before being signaled to issue a response. On most trials (80%), participants issued a standard naming response. On the remaining trials, they were cued to abandon the original speech plan, saying "blah" instead, thereby equating production across different words. Using feature-matched low- and high-frequency words, we observed the differences in pupil dilations as a function of word frequency. Indeed, frequency-sensitive cognitive demands were seen in word processing, even after naming responses were issued. The results suggest that word perception and/or speech planning requires the frequency-sensitive allocation of cognitive resources.

Fig. 1

Schematic outline of a single experimental trial

Fig. 2

Average baseline-corrected peak pupil diameters during the variable wait period, collapsed across trial types. Error bars represent standard errors. ^*p < .05

Fig. 3

Baseline-corrected peak pupil diameters for high-frequency (HF) and low-frequency (LF) words during each trial period for standard (top panel) and catch (bottom panel) trials, collapsed across delay conditions. Error bars represent standard errors. ^*p < .05. ^**p <.01

Fig. 4

Average pupil diameters (in millimeters) for high-frequency (HF) and low-frequency (LF) words from all trials with a 500-ms delay. The left panel shows results from standard trials, and the right panel shows catch trials. In both panels, the dots reflect average naming response times, with values shown in the inset boxes. The trial periods corresponding to word presentation and tone onset are indicated by vertical lines