Andreas Brocher

Pupil old/new effects reflect stimulus encoding and decoding in short-term memory

We conducted five pupil old/new experiments to examine whether pupil old/new effects can be linked to familiarity and/or recollection processes of recognition memory. In Experiments 1-3, we elicited robust pupil old/new effects for legal words and pseudowords (Experiment 1), positive and negative words (Experiment 2), and low-frequency and high-frequency words (Experiment 3). Importantly, unlike for old/new effects in ERPs, we failed to find any effects of long-term memory representations on pupil old/new effects. In Experiment 4, using the words and pseudowords from Experiment 1, participants made lexical decisions instead of old/new decisions. Pupil old/new effects were restricted to legal words. Additionally requiring participants to make speeded responses (Experiment 5) led to a complete absence of old/new effects. Taken together, these data suggest that pupil old/new effects do not map onto familiarity and recollection processes of recognition memory. They rather seem to reflect strength of memory traces in short-term memory, with little influence of long-term memory representations. Crucially, weakening the memory trace through manipulations in the experimental task significantly reduces pupil/old new effects.

Decision-related factors in pupil old/new effects: Attention, response execution, and false memory

&NA; In this study, we investigate the effects of decision‐related factors on recognition memory in pupil old/new paradigms. In Experiment 1, we used an old/new paradigm with words and pseudowords and participants made lexical decisions during recognition rather than old/new decisions. Importantly, participants were instructed to focus on the nonword‐likeness of presented items, not their word‐likeness. We obtained no old/new effects. In Experiment 2, participants discriminated old from new words and old from new pseudowords during recognition, and they did so as quickly as possible. We found old/new effects for both words and pseudowords. In Experiment 3, we used materials and an old/new design known to elicit a large number of incorrect responses. For false alarms (“old” response for new word), we found larger pupils than for correctly classified new items, starting at the point at which response execution was allowed (2750 ms post stimulus onset). In contrast, pupil size for misses (“new” response for old word) was statistically indistinguishable from pupil size in correct rejections. Taken together, our data suggest that pupil old/new effects result more from the intentional use of memory than from its automatic use. HighlightsTask‐related focus of attention affects pupil old/new effects.Response execution does not affect pupil old/new effects.Pupil old/new effects contain a veridical and a subjective component of oldness.Pupil old/new effects are more strongly related to the intentional than the automatic use of memory.

Effects of Information Status and Uniqueness Status on Referent Management in Discourse Comprehension and Planning

ABSTRACT In discourse processing, speakers collaborate toward a shared mental model by establishing and recruiting prominence relations between different discourse referents. In this article we investigate to what extent the possibility to infer a referent’s existence from preceding context (as indicated by the referent’s information status as inferred or brand-new) and a referent’s unique identifiability (as indicated by a referent’s uniqueness status) affect (1) ambiguous pronoun resolution in comprehension and (2) the bias to mention a referent again and make it topic in discourse planning. In Experiment 1, a visual-world eye-tracking experiment, we found that ambiguous pronouns are more likely to be interpreted as linked to the direct object of the preceding sentence when the associated referent was inferred and unique than when it was inferred and non-unique. For brand-new referents, uniqueness status did not affect ambiguous pronoun resolution. In Experiment 2, a story continuation experiment, we found that inferred and unique referents were mentioned again and made topic less often than inferred and non-unique referents as well as brand-new referents. Results are discussed within a dual-process activation model, which distinguishes the activation of a noun phrase’s concept through inference relations and the activation of a noun phrase’s referent through the referent’s uniqueness status.

About sharing and commitment: the retrieval of biased and balanced irregular polysemes

ABSTRACT We examined how the degree of semantic similarity between an ambiguous word’s meanings (homonyms vs. irregular polysemes) and meaning frequency (biased vs. balanced meanings) interact during lexical access and disambiguation. In Experiment 1, which was a continuous priming experiment, and with an ITI of 50 ms, we observed exhaustive access of meanings for all ambiguous words. With an ITI of 200 ms, we found a dominance effect for biased homonyms. There was no priming for biased irregular polysemes. For balanced homonyms and polysemes, we observed strong and roughly equivalent priming for target words associated with either meaning. In Experiment 2, using sentence reading, all ambiguous words elicited longer reading times in the absence of biasing context, while only biased and balanced homonyms also led to longer reading times in subsequent subordinate-biased context. Taken together, our data support a shared features model of irregular polyseme representation and retrieval.

Using task effort and pupil size to track covert shifts of visual attention independently of a pupillary light reflex

We tested the link between pupil size and the task effort involved in covert shifts of visual attention. The goal of this study was to establish pupil size as a marker of attentional shifting in the absence of luminance manipulations. In three experiments, participants evaluated two stimuli that were presented peripherally, appearing equidistant from and on opposite sides of eye fixation. The angle between eye fixation and the peripherally presented target stimuli varied from 12.5° to 42.5°. The evaluation of more distant stimuli led to poorer performance than did the evaluation of more proximal stimuli throughout our study, confirming that the former required more effort than the latter. In addition, in Experiment 1 we found that pupil size increased with increasing angle and that this effect could not be reduced to the operation of low-level visual processes in the task. In Experiment 2 the pupil dilated more strongly overall when participants evaluated the target stimuli, which required shifts of attention, than when they merely reported on the target’s presence versus absence. Both conditions yielded larger pupils for more distant than for more proximal stimuli, however. In Experiment 3, we manipulated task difficulty more directly, by changing the contrast at which the target stimuli were presented. We replicated the results from Experiment 1 only with the high-contrast stimuli. With stimuli of low contrast, ceiling effects in pupil size were observed. Our data show that the link between task effort and pupil size can be used to track the degree to which an observer covertly shifts attention to or detects stimuli in peripheral vision.