title: Task difficulty differentially affects two measures of processing load: the pupil response during sentence processing and delayed cued recall of the sentences.
abstract: OBJECTIVE
  In this study, the authors assessed the influence of masking level (29% or 71% sentence perception) and test modality on the processing load during language perception as reflected by the pupil response. In addition, the authors administered a delayed cued stimulus recall test to examine whether processing load affected the encoding of the stimuli in memory.
  
  
  METHODS
  Participants performed speech and text reception threshold tests, during which the pupil response was measured. In the cued recall test, the first half of correctly perceived sentences was presented, and participants were asked to complete the sentences. Reading and listening span tests of working memory capacity were presented as well.
  
  
  RESULTS
  Regardless of test modality, the pupil response indicated higher processing load in the 29% condition than in the 71% correct condition. Cued recall was better for the 29% condition.
  
  
  CONCLUSIONS
  The consistent effect of masking level on the pupil response during listening and reading support the validity of the pupil response as a measure of processing load during language perception. The absent relation between pupil response and cued recall may suggest that cued recall is not directly related to processing load, as reflected by the pupil response.
authors.affiliation: The EMGO+ Institute for Health and Care Research, VU University Medical Center, Amsterdam, the Netherlands. aa.zekveld@vumc.nl
authors.forename: Adriana A
authors.initials: AA
authors.lastname: Zekveld
authors.forename: Joost M
authors.initials: JM
authors.lastname: Festen
authors.forename: Sophia E
authors.initials: SE
authors.lastname: Kramer
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000293:Adolescent; D000328:Adult; D001309:Auditory Threshold / Q000502:physiology; D003463:Cues; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D011939:Mental Recall / Q000502:physiology*; D009622:Noise; D010470:Perceptual Masking / Q000502:physiology*; D011932:Reading; D012025:Reflex, Pupillary / Q000502:physiology*; D013063:Speech Discrimination Tests; D013067:Speech Perception / Q000502:physiology*; D014706:Verbal Learning / Q000502:physiology*; D055815:Young Adult
keywords: processing load; pupil response; speech recall; speech recognition; text perception threshold (TRT)