Differences In Response Bias Research Articles

When 2 become 1: Autistic simultaneity judgements about asynchronous audiovisual speech.

It has been proposed that autistic people experience a temporal distortion whereby the temporal binding window of multisensory integration is extended. Research to date has focused on autistic children so whether these differences persist into adulthood remains unknown. In addition, the possibility that the previous observations have arisen from between-group differences in response bias, rather than perceptual differences, has not been addressed. Participants completed simultaneity judgements of audiovisual speech stimuli across a range of stimulus-onset asynchronies. Response times and accuracy data were fitted to a drift-diffusion model so that the drift rate (a measure of processing efficiency) and starting point (response bias) could be estimated. In Experiment 1, we tested a sample of non-autistic adults who completed the Autism Quotient questionnaire. Autism Quotient score was not correlated with either drift rate or response bias, nor were there between-group differences when splitting based on the first and third quantiles of scores. In Experiment 2, we compared the performance of autistic with a group of non-autistic adults. There were no between-group differences in either drift rate or starting point. The results of this study do not support the previous suggestion that autistic people have an extended temporal binding window for audiovisual speech. In addition, exploratory analysis revealed that operationalising the temporal binding window in different ways influenced whether a group difference was observed, which is an important consideration for future work.

Enhanced decision-making in nicotine dependent individuals who abstain: A computational analysis using Hierarchical Drift Diffusion Modeling

BackgroundVariability in decision-making capacity and reward responsiveness may underlie differences in the ability to abstain from smoking. Computational modeling of choice behavior, as with the Hierarchical Drift Diffusion Model (HDDM), can help dissociate reward responsiveness from underlying components of decision-making. Here we used the HDDM to identify which decision-making or reward-related parameters, extracted from data acquired in a reward processing task, contributed to the ability of people who smoke that are not seeking treatment to abstain from cigarettes during a laboratory task. Methods80 adults who smoke cigarettes completed the Probabilistic Reward Task (PRT) - a signal detection task with a differential reinforcement schedule - following smoking as usual, and the Relapse Analogue Task (RAT) - a task in which participants could earn money for delaying smoking up to 50min - after a period of overnight abstinence. Two cohorts were defined by the RAT; those who waited either 0-min (n=36) or the full 50-min (n=44) before smoking. ResultsPRT signal detection metrics indicated all subjects learned the task contingencies, with no differences in response bias or discriminability between the two groups. However, HDDM analyses indicated faster drift rates in 50-min vs. 0-min waiters. ConclusionsRelative to those who did not abstain, computational modeling indicated that people who abstained from smoking for 50min showed faster evidence accumulation during reward-based decision-making. These results highlight the importance of decision-making mechanisms to smoking abstinence, and suggest that focusing on the evidence accumulation process may yield new targets for treatment.

Interactions Between Breathy and Rough Voice Qualities and Their Contributions to Overall Dysphonia Severity.

Dysphonic voices typically present multiple voice quality dimensions. This study investigated potential interactions between perceived breathiness and roughness and their contributions to overall dysphonia severity. Synthetic stimuli based on four talkers were created to systematically map out potential interactions. For each talker, a stimulus matrix composed of 49 stimuli (seven breathiness steps × seven roughness steps) was created by varying aspiration noise and open quotient to manipulate breathiness and superimposing amplitude modulation of varying depths to simulate roughness. One-dimensional matching (1DMA) and magnitude estimation (1DME) tasks were used to measure perceived breathiness, roughness, their potential interactions, and overall dysphonia severity. Additional 1DME tasks were used to assess a set of natural stimuli that varied along both breathiness and roughness. For the synthetic stimuli, the 1DMA task indicated little interaction between the two voice qualities. For the 1DME task, breathiness magnitude was influenced by roughness step to a greater extent than roughness magnitude was influenced by breathiness step. The additive contributions of breathiness and roughness to overall severity gradually diminished with increasing breathiness and roughness steps, possibly reflecting a ceiling effect in the 1DME task. For the natural stimuli, little consistent interaction was observed between breathiness and roughness. The matching task revealed minimal interaction between perceived breathiness and roughness, whereas the magnitude estimation task revealed some interaction between the two qualities and their cumulative contributions to overall dysphonia severity. Task differences are discussed in terms of differences in response bias and the role of perceptual anchors. https://doi.org/10.23641/asha.21313701.

Reinvestigation of the Psychological Mechanisms of Construction Experience on Hazard Recognition Performance.

The study aimed to reinvestigate psychological mechanisms of the influence of construction workers' experience on hazard recognition performance, with signal detection theory (SDT) and electroencephalogram (EEG) readings. Existing evidence regarding the effect of experience on hazard recognition performance in the construction industry remains inconsistent. Behavior-wise, identification of dominant hazard recognition factors (sensitivity or response bias, or both) would help determine appropriate training strategies to improve hazard recognition. In terms of neuro-responses, induced gamma-band activity was expected to reflect the cognitive functions mediating the psychological effects of experience. Seventy-seven construction workers participated in a predesigned hazard recognition task, in which participants judged whether a hazard was present from a series of construction scenario pictures. We computed and compared the sensitivity and response bias of SDT and time-frequency representations of recorded EEG signals of the two experience-level groups. Novice workers had higher hazard recognition rates. Behavior-wise, novices were more sensitive than more experienced workers. Compared with experienced workers, novices showed stronger gamma-band difference power (hazardous minus safe) in the left frontal and right posterior parietal areas during the hazard recognition process. Novices performed better at hazard recognition, indicating their sensitivity to the hazards without a clear difference in response bias. Based on the EEG data, novices' sensitivity may be attributed to more efficient working memory and attentional control. There is a need for continuous refreshment of hazard recognition skills for experienced workers for safety interventions.

Diagnostic and dimensional evaluation of implicit reward learning in social anxiety disorder and major depression.

Increasing evidence supports the presence of an anhedonic endophenotype in major depressive disorder (MDD), characterized by impairments in various components of reward processing, particularly incentive motivation, effort-based decision making, and reward learning. In addition to its prominent role in MDD, reward processing dysregulation has been proposed as a transdiagnostic risk and/or maintenance factor for a range of other forms of psychopathology. Individuals with social anxiety disorder (SAD)-a condition that frequently co-occurs with MDD-demonstrate low trait positive affectivity and altered processing of rewards and positively valenced information. However, no studies to date have directly tested reward learning-the ability to modulate behavior in response to rewards-in this population. The current study evaluated reward learning in MDD, SAD, and healthy control subjects (N = 90) using a well-validated signal detection task. Given increasing data supporting transdiagnostic features of psychopathology, we also evaluated associations between anhedonia and task performance transdiagnostically in the patient sample. Contrary to expectations, results indicated no significant group differences in response bias in the full sample, suggesting no diagnostic differences in reward learning. However, dimensional analyses revealed that higher self-reported anhedonia (but not general distress or anxious arousal) was associated with worse reward learning in both the MDD and SAD groups explaining about 11% of the variance. Deficits in implicit reward learning are associated with anhedonia but not necessarily with major depressive disorder as a diagnosis, which supports the use of transdiagnostic approaches to understanding psychopathology.

Reward Functioning Abnormalities in Adolescents at High Familial Risk for Depressive Disorders

BackgroundA parental history of major depressive disorder (MDD) is an established risk factor for MDD in youth, and clarifying the mechanisms related to familial risk transmission is critical. Aberrant reward processing is a promising biomarker of MDD risk; accordingly, the aim of this study was to test behavioral measures of reward responsiveness and underlying frontostriatal resting activity in healthy adolescents both with (high-risk) and without (low-risk) a maternal history of MDD. MethodsLow-risk and high-risk 12- to 14-year-old adolescents completed a probabilistic reward task (n = 74 low-risk, n = 27 high-risk) and a resting-state functional magnetic resonance imaging scan (n = 61 low-risk, n = 25 high-risk). Group differences in response bias toward reward and resting ventral striatal and medial prefrontal cortex (mPFC) fractional amplitude of low-frequency fluctuations (fALFFs) were examined. Computational modeling was applied to dissociate reward sensitivity from learning rate. ResultsHigh-risk adolescents showed a blunted response bias compared with low-risk adolescents. Computational modeling analyses revealed that relative to low-risk adolescents, high-risk adolescents exhibited reduced reward sensitivity but similar learning rate. Although there were no group differences in ventral striatal and mPFC fALFFs, groups differed in their relationships between mPFC fALFFs and response bias. Specifically, among high-risk adolescents, higher mPFC fALFFs correlated with a blunted response bias, whereas there was no fALFFs–response bias relationship among low-risk youths. ConclusionsHigh-risk adolescents exhibit reward functioning impairments, which are associated with mPFC fALFFs. The blunted response bias–mPFC fALFFs association may reflect an excessive mPFC-mediated suppression of reward-driven behavior, which may potentiate MDD risk.

When in doubt, it’s not out: Match format is associated with differences in elite-level cricket umpires’ leg-before-wicket decisions

ObjectivesContextual factors can influence the way sports officials apply unambiguous rules. The aim of this study was to better understand the leg-before-wicket (LBW) decision-making behaviour of elite cricket umpires and determine whether their behaviour changes according to the format of the game in which they are adjudicating. MethodsLBW decisions (n = 5578) from actual elite level cricket matches in Australia between 2009 and 2016 were analysed using a signal detection paradigm. Umpire sensitivity (A) and response bias (B) were compared to chance performance in three formats of the game: Four-day, One-day, and T20. Mixed effects models assessed sensitivity and response bias differences between match types. ResultsUmpires were able to differentiate between “out” and “not out” appeals to a high standard but were conservative and had a bias to respond “not out” in all formats of the game. Umpires were less accurate in the shorter formats of the game, particularly T20 cricket and were also significantly more conservative in T20 compared to Four-day Matches. ConclusionsCricket umpires are conservative and are highly accurate LBW decision makers. However, differences in their judgments were associated with different match formats. The unique task goals and contextual pressures afforded by the shorter formats of the game, particularly T20, may account for the observed performance differences we see here.

Differences in Discriminability and Response Bias on Rey Auditory Verbal Learning Test Delayed Recognition in Behavioral Variant Frontotemporal Dementia and Alzheimer's Disease.

Episodic memory is impaired in Alzheimer's disease (AD) dementia but thought to be relatively spared in behavioral variant frontotemporal dementia (bvFTD). This view is challenged by evidence of memory impairment in bvFTD. This study investigated differences in recognition memory performance between bvFTD and AD. We performed a retrospective analysis on the recognition trial of the Rey Auditory Verbal Learning Test in patients with bvFTD (n = 85), AD (n = 55), and control participants (n = 59). Age- and education-adjusted between-group analysis was performed on the total score and indices of discriminative ability and response bias. Correlations between recognition and measures of memory, language, executive functioning, and construction were examined. Patients with AD had a significantly lower total recognition score than patients with bvFTD (control 28.8 ± 1.5; bvFTD 24.8 ± 4.5; AD 23.4 ± 3.6, p < .01). Both bvFTD and AD had worse discriminative ability than controls (A' control 0.96 ± 0.03; bvFTD 0.87 ± 0.03; AD 0.84 ± 0.10, p < .01), but there was no difference in response bias (B" control 0.9 ± 0.2; bvFTD 1.6 ± 1.47; AD 1.4± 1.4, p < .01). AD had worse discriminability than bvFTD (p < .05). Discriminability was associated with memory for both patient groups (median correlation coefficient r = .34) and additionally associated with language (r = .31), but not executive functioning (r = -.03) in bvFTD. Response bias was unrelated to other cognitive functions (r = -.02). Discriminability, but not response bias, differentiated patients with bvFTD from AD. The presence of an impaired discrimination index suggests a "pure" (recognition) memory deficit in bvFTD.

P2‐451: RECOGNITION MEMORY PERFORMANCE AS A COGNITIVE MARKER OF PRODROMAL ALZHEIMER'S DISEASE

The utility of recognition memory indices for identifying persons with biological evidence of Alzheimer's disease is unclear, as studies have diagnosed mild cognitive impairment due to AD using clinical criteria rather than CSF measures of central amyloidosis and tauopathy. We evaluated whether recognition memory indices of discriminability and response bias derived from signal detection theory differentiate persons with amnestic MCI with positive CSF evidence of AD (prodromal AD) vs. non-prodromal amnestic MCI. 133 participants in the VAScular ContribUtors to ProdromaL AlzheimeR's disease (VASCULAR) study were clinically diagnosed at their screening evaluations with amnestic MCI using ADNI criteria including a subjective memory complaint, impaired performance on Logical Memory, 0.5 on the CDR memory box, and relatively preserved IADLs (FAQ). At their baseline visit, they received the Hopkins Verbal Learning Test-Revised which assesses learning and recall of 12 words, followed by delayed recall and recognition (12 targets, 12 foils). Participants also underwent LPs, and AD biomarkers were measured (ALZBIO3) in Dr. Leslie Shaw's lab (U.Penn). Participants were classified as prodromal AD if they had a tau/amyloid ratio of ≥0.45 using previously published cutoffs (Shaw et al., Alzheimers Dement 10:698-705, 2018). 34 (26%) MCI participants had prodromal AD. They were significantly older (72.2±6.8 years) and had lower MoCA scores (20.9±2.6 points) than the non-prodromal group (64.6±8.5 years; 22.4±2.8 points), but did not differ in education (15.8±2.9 years vs. 15.5±3.1 years). ANCOVAs controlling for age and MoCA scores demonstrated differences in hits (Prodromal: 9.5±2.9, non-Prodromal: 11.2±1.2, p=.004) but not false alarms (Prodromal: 2.1±1.9; non-Prodromal 1.3±1.4, p=.14). A discriminability measure (d’) which simultaneously considers hits and false alarms was lower in the prodromal (2.0±1.9) vs. non-prodromal (5.1±2.2) groups, p<.001. A cutoff of 5.0 had 71% sensitivity and 70% specificity, with 93/133 participants correctly classified. There were no significant differences in response bias (Prodromal: .12±1.3; non-Prodromal: −.42±1.2, p=.10). Individuals with amnestic MCI due to prodromal AD are less accurate in distinguishing targets from foils. Discriminability may serve as a marker of prodromal AD and could be utilized with other memory indices to facilitate differential diagnosis of amnestic MCI due to AD vs. non-AD etiologies.

A meta-analysis of differences in children's reports of single and repeated events.

When children report abuse, they often report that it occurred repeatedly. In most jurisdictions, children will be asked to report each instance of abuse with as many details as possible. In the current meta-analysis, we analyzed data from 31 experiments and 3099 children. When accuracy was defined as the number of correct details from the target instance (i.e., narrow definition), repeated-event children were less accurate than single-event children. However, we argue that defining accuracy as the number of reported details that were experienced across instances (i.e., broad definition) is more appropriate for repeated events. When a broad definition was applied, single- and repeated-event children were similarly accurate. Importantly, repeated-event children were less likely than single-event children to report details that had never been experienced and they were no more likely to say "I don't know." Overall, repeated-event children were more suggestible than single-event children, but this was moderated by length of delay to recall. In analyses of recognition data, single-event children's sensitivity score was higher than repeated-event children's, with no significant difference in response bias as a function of event frequency. We discuss these results in the context of how children's memory for repeated events is organized. We also consider the advantage of applying a broad definition of accuracy for victims of repeated abuse and charging repeated abuse as a continuous offense rather than discrete acts. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

How can we improve identification of contagious individuals? Factors influencing sickness detection.

The comment by Kurvers and Wolf [1] on our recent publication [2] highlights some urgent questions that emerge not only in the wake of our study, but also in relation to the developing field of how behavioural mechanisms have evolved to defend against microbial infections. Their additional analyses of our data show that, even though there were small individual differences in the ability to discriminate between healthy and sick individuals (although some expert raters were identified), there were substantial differences in response bias, that is, how individuals balance the trade-off between sensitivity and specificity. Kurvers and Wolf also focus on how social-learning strategies could influence the detection of disease cues, and thereby disease dynamics, in the population in relation to the social network position of the ‘detector’. Thus, how do individuals differ in their ability to discriminate between sick and healthy peers, and in what way can social information—learning from others—influence one's responses to potentially sick people? There are good reasons …

Interaction effects on common measures of sensitivity: choice of measure, type I error, and power.

Here we use simulation to assess previously unaddressed problems in the assessment of statistical interactions in detection and recognition tasks. The proportion of hits and false-alarms made by an observer on such tasks is affected by both their sensitivity and bias, and numerous measures have been developed to separate out these two factors. Each of these measures makes different assumptions regarding the underlying process and different predictions as to how false-alarm and hit rates should covary. Previous simulations have shown that choice of an inappropriate measure can lead to inflated type I error rates, or reduced power, for main effects, provided there are differences in response bias between the conditions being compared. Interaction effects pose a particular problem in this context. We show that spurious interaction effects in analysis of variance can be produced, or true interactions missed, even in the absence of variation in bias. Additional simulations show that variation in bias complicates patterns of type I error and power further. This under-appreciated fact has the potential to greatly distort the assessment of interactions in detection and recognition experiments. We discuss steps researchers can take to mitigate their chances of making an error.

Influence of encoding instructions and response bias on cross-cultural differences in specific recognition.

Prior cross-cultural research has reported cultural variations in memory. One study revealed that Americans remembered images with more perceptual detail than East Asians (Millar et al. in Cult Brain 1(2-4):138-157, 2013). However, in a later study, this expected pattern was not replicated, possibly due to differences in encoding instructions (Paige et al. in Cortex 91:250-261, 2017). The present study sought to examine when cultural variation in memory-related decisions occur and the role of instructions. American and East Asian participants viewed images of objects while making a Purchase decision or an Approach decision and later completed a surprise recognition test. Results revealed Americans had higher hit rates for specific memory, regardless of instruction type, and a less stringent response criterion relative to East Asians. Additionally, a pattern emerged where the Approach decision enhanced hit rates for specific memory relative to the Purchase decision only when administered first; this pattern did not differ across cultures. Results suggest encoding instructions do not magnify cross-cultural differences in memory. Ultimately, cross-cultural differences in response bias, rather than memory sensitivity per se, may account for findings of cultural differences in memory specificity.

Influence of response bias and internal/external source on lateral posterior parietal successful retrieval activity

In studies of recognition memory, regions of the lateral posterior parietal cortex exhibit greater activity (as indexed by the fMRI BOLD signal) during correct recognition of “old” (studied) items than correct rejection of “new” (unstudied) items. This effect appears to be source-sensitive, with greater activity associated with recognition of perceived than imagined events. Parietal successful retrieval activity also varies with response bias, or the tendency to be conservative about making “old” judgments. Here, we examined whether differences in response bias associated with recognition judgments of perceived and imagined events could account for source-based differences in LPPC activity. Participants perceived and imagined items in response to cue words and then at test, made recognition judgments in blocks that knowingly contained either a high or low proportion of old to new trials. While participants were indeed more conservative when making judgments about perceived than imagined events, the neuroimaging results demonstrated that response bias and source effects occurred in non-overlapping parietal regions. These findings suggest that source-based differences in LPPC activity cannot be explained by differences in response bias associated with recognizing perceived and imagined events.

Unpacking buyer-seller differences in valuation from experience: A cognitive modeling approach

People often indicate a higher price for an object when they own it (i.e., as sellers) than when they do not (i.e., as buyers)—a phenomenon known as the endowment effect. We develop a cognitive modeling approach to formalize, disentangle, and compare alternative psychological accounts (e.g., loss aversion, loss attention, strategic misrepresentation) of such buyer-seller differences in pricing decisions of monetary lotteries. To also be able to test possible buyer-seller differences in memory and learning, we study pricing decisions from experience, obtained with the sampling paradigm, where people learn about a lottery’s payoff distribution from sequential sampling. We first formalize different accounts as models within three computational frameworks (reinforcement learning, instance-based learning theory, and cumulative prospect theory), and then fit the models to empirical selling and buying prices. In Study 1 (a reanalysis of published data with hypothetical decisions), models assuming buyer-seller differences in response bias (implementing a strategic-misrepresentation account) performed best; models assuming buyer-seller differences in choice sensitivity or memory (implementing a loss-attention account) generally fared worst. In a new experiment involving incentivized decisions (Study 2), models assuming buyer-seller differences in both outcome sensitivity (as proposed by a loss-aversion account) and response bias performed best. In both Study 1 and 2, the models implemented in cumulative prospect theory performed best. Model recovery studies validated our cognitive modeling approach, showing that the models can be distinguished rather well. In summary, our analysis supports a loss-aversion account of the endowment effect, but also reveals a substantial contribution of simple response bias.

Response bias-related impairment of early subjective face discrimination in social anxiety disorders: An event-related potential study

Considerable research has shown that social anxiety disorder (SAD) is accompanied by various negative cognitive biases, such as social feedback expectancy bias, memory bias, and interpretation bias. However, whether the memory bias in individuals with SAD is actually a manifestation of response bias, and whether such response bias is associated with deficits in face discrimination, remains unclear. In the present study, we investigated response bias (i.e., a tendency to recognize more negative evaluations) to faces with positive (social acceptance) or negative (social rejection) social evaluations in individuals with SAD and healthy controls (HCs) using event-related potentials (ERPs). Behavioral results revealed significant group differences in response bias in the forced-choice recall task, but no difference in overall memory accuracy. ERP results demonstrated that HCs showed a larger N170 to faces that had rejected them as compared to those that had accepted them, but this effect was not evident in the SAD group. Further analysis showed that response bias was correlated with the ΔN170 (rejected – accepted) amplitude. We concluded that the response bias in individuals with SAD is resulted from impairments in early discrimination of social faces, as reflected by the absent early N170 differentiation effect, which was associated with their combined negative biases.

DIFFERENCES IN OLFACTORY DETECTION AND RESPONSE BIAS IN THE 3XTG-AD AND 5XFAD MOUSE MODELS OF ALZHEIMER’S DISEASE

DIFFERENCES IN OLFACTORY DETECTION AND RESPONSE BIAS IN THE 3XTG-AD AND 5XFAD MOUSE MODELS OF ALZHEIMER’S DISEASE

Sex Differences in Music: A Female Advantage at Recognizing Familiar Melodies.

Although sex differences have been observed in various cognitive domains, there has been little work examining sex differences in the cognition of music. We tested the prediction that women would be better than men at recognizing familiar melodies, since memories of specific melodies are likely to be learned (at least in part) by declarative memory, which shows female advantages. Participants were 24 men and 24 women, with half musicians and half non-musicians in each group. The two groups were matched on age, education, and various measures of musical training. Participants were presented with well-known and novel melodies, and were asked to indicate their recognition of familiar melodies as rapidly as possible. The women were significantly faster than the men in responding, with a large effect size. The female advantage held across musicians and non-musicians, and across melodies with and without commonly associated lyrics, as evidenced by an absence of interactions between sex and these factors. Additionally, the results did not seem to be explained by sex differences in response biases, or in basic motor processes as tested in a control task. Though caution is warranted given that this is the first study to examine sex differences in familiar melody recognition, the results are consistent with the hypothesis motivating our prediction, namely that declarative memory underlies knowledge about music (particularly about familiar melodies), and that the female advantage at declarative memory may thus lead to female advantages in music cognition (particularly at familiar melody recognition). Additionally, the findings argue against the view that female advantages at tasks involving verbal (or verbalizable) material are due solely to a sex difference specific to the verbal domain. Further, the results may help explain previously reported cognitive commonalities between music and language: since declarative memory also underlies language, such commonalities may be partly due to a common dependence on this memory system. More generally, because declarative memory is well studied at many levels, evidence that music cognition depends on this system may lead to a powerful research program generating a wide range of novel predictions for the neurocognition of music, potentially advancing the field.

Individual differences in incorrect responding and the ability to discriminate the source of the products of retrieval.

When memory is tested, researchers are often interested in the items that were correctly recalled or recognized, while ignoring or factoring out trials where one "recalls" or "recognizes" a nonstudied item. However, intrusions and false alarms are more than nuisance data and can provide key insights into the memory system. The present article reports 2 experiments demonstrating that people are remarkably consistent in the rate at which they incorrectly report memory for nonstudied items, even across a range of differing stimuli and test features. Experiment 1 found that individual differences in false alarms and intrusions were strongly related, even while controlling for the shared influence of memory ability on these incorrect response types. Furthermore, intrusion rate was found to be related to response bias as well, but this effect was suppressed by the shared influence of memory ability, demonstrating that an independent measure of memory ability is an important control in investigations into individual differences in response bias. Experiment 2 revealed that the relations between intrusions and false alarm rate and response bias were entirely explained by one's ability to discriminate episodic memories from semantic generation. This work links together previous work on individual differences in intrusions and in false alarms, and highlights the ability to identify the source of a memory as the key cognitive trait underlying incorrect response styles on various memory tests. (PsycINFO Database Record

Extraversion and Recognition for Emotional Words: Effects of Valence, Frequency, and Task-difficulty

In this study, memory for emotional words was compared between extraverts and introverts, employing signal detection analysis to distinguish differences in discriminative memory and response bias. Subjects were presented with a study list of emotional words in an encoding session, followed by a recognition session. Effects of task difficulty were examined by varying the nature of the encoding task and the intervals between study and test. For an easy task, with a retention interval of 5 minutes (Study I), introverts exhibited better memory (i.e., higher d′) than extraverts, particularly for low-frequency words, and response biases did not differ between these two groups. For a difficult task, with a one-month retention period (Study II), performance was poor overall, and only high-frequency words were remembered; also extraverts adopted a more liberal criterion for ‘old’ responses (i.e., more hits and more false alarms) for positive emotional-valence words. These results suggest that as task difficulty drives down performance, effects of internal control processes become more apparent, revealing differences in response biases for positive words between extraverts and introverts. These results show that extraversion can distort memory performance for words, depending on their emotional valence.