Saying “yes” when you want to say “no” - pupil dilation reflects evidence accumulation in a visual working memory recognition task (original) (raw)
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Pupil dilation during recognition memory: Isolating unexpected recognition from judgment uncertainty
Cognition, 2016
Optimally discriminating familiar from novel stimuli demands a decision-making process informed by prior expectations. Here we demonstrate that pupillary dilation (PD) responses during recognition memory decisions are modulated by expectations, and more specifically, that pupil dilation increases for unexpected compared to expected recognition. Furthermore, multi-level modeling demonstrated that the time course of the dilation during each individual trial contains separable early and late dilation components, with the early amplitude capturing unexpected recognition, and the later trailing slope reflecting general judgment uncertainty or effort. This is the first demonstration that the early dilation response during recognition is dependent upon observer expectations and that separate recognition expectation and judgment uncertainty components are present in the dilation time course of every trial. The findings provide novel insights into adaptive memory-linked orienting mechanisms ...
Psychophysiology, 2017
The attentional learning theory of Pearce and Hall (1980) predicts more attention to uncertain cues that have caused a high prediction error in the past. We examined how the cue-elicited pupil dilation during associative learning was linked to such errordriven attentional processes. In three experiments, participants were trained to acquire associations between different cues and their appetitive (Experiment 1), motor (Experiment 2), or aversive (Experiment 3) outcomes. All experiments were designed to examine differences in the processing of continuously reinforced cues (consistently followed by the outcome) versus partially reinforced, uncertain cues (randomly followed by the outcome). We measured the pupil dilation elicited by the cues in anticipation of the outcome and analyzed how this conditioned pupil response changed over the course of learning. In all experiments, changes in pupil size complied with the same basic pattern: During early learning, consistently reinforced cues elicited greater pupil dilation than uncertain, randomly reinforced cues, but this effect gradually reversed to yield a greater pupil dilation for uncertain cues toward the end of learning. The pattern of data accords with the changes in prediction error and error-driven attention formalized by the Pearce-Hall theory.
Your effort is showing! Pupil dilation reveals memory heuristics
Constructions of remembering and …, 2011
It is an honor to contribute to a collection of essays celebrating Bruce Whittlesea"s career. The research and ideas from Whittlesea and his colleagues have heavily influenced much of the research in our laboratory, particularly our studies of face perception and memory. Although face processing is often considered "modular" (i.e., highly specialized in neural and computational terms; Haxby, , we have consistently observed that judgments of face memory are affected by the evaluative and heuristic processes that Whittlesea has hypothesized (e.g. . In this chapter, we briefly review several prior findings that connect Whittlesea"s (1997) SCAPE framework with face memory. We then describe new results, wherein we hypothesize that long-term struggles from the SCAPE evaluation system may inspire a new heuristic (kindly dubbed the "oh… screw it" heuristic).
The pupil as an indicator of unconscious memory: Introducing the pupil priming effect
Psychophysiology, 2015
We explored whether object behavioral priming and pupil changes occur in the absence of recognition memory. Experiment 1 found behavioral priming for unrecognized objects (Ms) regardless of whether they had been encoded perceptually or conceptually. Using the same perceptual encoding task, Experiment 2 showed greater pupil dilation for Ms than for correct rejections of unstudied objects (CRs) when reaction times were matched. In Experiment 3, there was relatively less pupil dilation for Ms than for similarly matched CRs when objects had been encoded conceptually. Mean/peak pupil dilation for CRs, but not Ms, increased in Experiment 3, in which novelty expectation was also reduced, and the pupillary time course for both Ms and CRs was distinct in the two experiments. These findings indicate that both behavioral and pupil memory occur for studied, but unrecognized stimuli, and suggest that encoding and novelty expectation modulate pupillary memory responses.
Pupil dilation but not microsaccade rate robustly reveals decision formation
Scientific Reports, 2018
Pupil dilation, an indicator of arousal that is generally regarded as unspecific, amongst others reflects decision formation and reveals choice. Employing letter selection in a Go/NoGo task, we show that choice can robustly be predicted by the pupillary signal, even under the presence of strong interfering factors such as changes in brightness or motor execution. In addition, a larger difference in pupil dilation between target and distractor conditions for NoGo compared to Go was demonstrated, underlining the particular appropriateness of the paradigm for decision research. Incorporating microsaccades, a variable that is suggested to covary with pupil diameter, we show that decision formation can only be observed in pupil diameter. However, microsaccade rate and pupil size covaried for motor execution and both reflected choice after key press with smaller effect size for microsaccade rate. We argue that combining pupil dilation and microsaccade rate may help dissociating decision-related changes in pupil diameter from interfering factors. Considering the interlinked main neural correlates of pupil dilation and microsaccade generation, these findings point to a selective role of locus coeruleus compared to superior colliculus in decision formation. Variations in pupil diameter, at constant brightness and viewing distance, are a popular but unspecific indicator of cognitive 1 and affective processing 2-5. Pupil diameter reportedly tracks the activity of noradrenergic locus coeruleus (LC) 6-11. The hereby modulated arousal level might thus contribute to the covariation of various mental processes and pupil diameter. Decision making has been investigated by means of pupillometry in several tasks 5,7,9,12-18. It was found that pupils dilate stronger when deciding for "yes" than for "no" in a signal detection task, likely reflecting the accumulation of information until a response criterion is reached 18,19. Furthermore, manual responses could be predicted, suggesting that pupil dilation not only reflects choice, but also the foregoing decision formation 12,19. Given the low specificity of pupil diameter, it remains doubtable whether decision formation and choice can still be identified in the presence of several other factors. This is especially the case in the presence of factors producing considerably larger effects like, for example, brightness changes. Two approaches might serve for compensating the missing specificity; firstly, one might disentangle interfering effects, or, secondly, one might add a further variable. Both approaches were pursued by examining pupil responses in a decision task including strong interference factors such as a sudden change in brightness, a key press, a tone, and four directions of incoming saccades while simultaneously tracking microsaccade rate. Pupil size and microsaccade rate respond to similar psychological phenomena even when stimulus material is kept constant regarding its sensory and spatial characteristics: Two recent investigations combined pupil dilation and microsaccade rate in the context of visual search and found an overlap in results between the two variables 20,21. Similarly, in an oddball paradigm, it is claimed that microsaccade rate might change differentially for odd stimuli in comparison to other stimuli 22,23 , while it has been reported that pupil dilation is also affected by the oddness of a stimulus 8. Another psychological phenomenon that is linked to changes in pupil diameter and microsaccade rate is cognitive load 24,25. Here, higher workload is associated with larger pupils and a lower rate of microsaccades 25. Moreover, also neural correlates of pupil dilation, locus coeruleus (LC), and of microsaccade rate, superior colliculus (SC), are reported to be closely connected 8,18,26. Correspondingly, in animal experiments, microstimulation in the SC and in the LC is associated with pupil dilations 6,26. Interestingly, despite finding a close correlation of activity in brainstem nuclei, also including LC and SC, only activity in LC, but not in SC predicted changes in decision bias during evidence accumulation for decision making 18. Therefore, during decision
Keeping an eye on the truth? Pupil size changes associated with recognition memory
During recognition memory tests participants’ pupils dilate more when they view old items compared to novel items. We sought to replicate this “pupil old/new effect” and to determine its relationship to participants’ responses. We compared changes in pupil size during recognition when participants were given standard recognition memory instructions, instructions to feign amnesia and instructions to report all items as new. Participants’ pupils dilated more to old items compared to new items under all three instruction conditions. This finding suggests that the increase in pupil size that occurs when participants encounter previously studied items is not under conscious control. Given that pupil size can be reliably and simply measured, the pupil old/new effect may have potential in clinical settings as a means for determining whether patients are feigning memory loss.
Differences in pupil dilation are observed for studied compared to new items in recognition memory. According to cognitive load theory, this effect reflects the greater cognitive demands of retrieving contextual information from study phase. Pupil dilation can also occur when new items conceptually related to old ones are erroneously recognized as old, but the aspects of similarity that modulate false memory and related pupil responses remain unclear. We investigated this issue by manipulating the degree of featural similarity between new (unstudied) and old (studied) concepts in an old/new recognition task. We found that new concepts with high similarity were mistakenly identified as old and had greater pupil dilation than those with low similarity, suggesting that pupil dilation reflects the strength of evidence on which recognition judgments are based and, importantly, greater locus coeruleus and prefrontal activity determined by the higher degree of retrieval monitoring involved...
Pupil dilation signals surprise: evidence for noradrenaline’s role in decision making
Frontiers in Neuroscience, 2011
Our decisions are guided by the rewards we expect. These expectations are often based on incomplete knowledge and are thus subject to uncertainty. While the neurophysiology of expected rewards is well understood, less is known about the physiology of uncertainty. We hypothesize that uncertainty, or more specifically errors in judging uncertainty, are reflected in pupil dilation, a marker that has frequently been associated with decision making, but so far has remained largely elusive to quantitative models. To test this hypothesis, we measure pupil dilation while observers perform an auditory gambling task. This task dissociates two key decision variables -uncertainty and reward -and their errors from each other and from the act of the decision itself. We first demonstrate that the pupil does not signal expected reward or uncertainty per se, but instead signals surprise, that is, errors in judging uncertainty. While this general finding is independent of the precise quantification of these decision variables, we then analyze this effect with respect to a specific mathematical model of uncertainty and surprise, namely risk and risk prediction error. Using this quantification, we find that pupil dilation and risk prediction error are indeed highly correlated. Under the assumption of a tight link between noradrenaline (NA) and pupil size under constant illumination, our data may be interpreted as empirical evidence for the hypothesis that NA plays a similar role for uncertainty as dopamine does for reward, namely the encoding of error signals.
Frontiers in Psychology, 2021
Research on pupillometry provides an increasing evidence for associations between pupil activity and memory processing. The most consistent finding is related to an increase in pupil size for old items compared with novel items, suggesting that pupil activity is associated with the strength of memory signal. However, the time course of these changes is not completely known, specifically, when items are presented in a running recognition task maximizing interference by requiring the recognition of the most recent items from a sequence of old/new items. The sample comprised 42 healthy participants who performed a visual word recognition task under varying conditions of retention interval. Recognition responses were evaluated using behavioral variables for discrimination accuracy, reaction time, and confidence in recognition decisions. Pupil activity was recorded continuously during the entire experiment. The results suggest a decrease in recognition performance with increasing study-t...
PLoS ONE, 2012
Studies on cognitive effort have shown that pupil dilation is a reliable indicator of memory load. However, it is conceivable that there are other sources of effort involved in memory that also affect pupil dilation. One of these is the ease with which an item can be retrieved from memory. Here, we present the results of an experiment in which we studied the way in which pupil dilation acts as an online marker for memory processing during the retrieval of paired associates while reducing confounds associated with motor responses. Paired associates were categorized into sets containing either 4 or 7 items. After learning the paired associates once, pupil dilation was measured during the presentation of the retrieval cue during four repetitions of each set. Memory strength was operationalized as the number of repetitions (frequency) and set-size, since having more items per set results in a lower average recency. Dilation decreased with increased memory strength, supporting the hypothesis that the amplitude of the evoked pupillary response correlates positively with retrieval effort. Thus, while many studies have shown that ''memory load'' influences pupil dilation, our results indicate that the task-evoked pupillary response is also sensitive to the experimentally manipulated memory strength of individual items. As these effects were observed well before the response had been given, this study also suggests that pupil dilation can be used to assess an item's memory strength without requiring an overt response.