Linear theory, dimensional theory, and the face-inversion effect

High familiar faces have both eye recognition and holistic processing advantages

People recognize familiar faces better than unfamiliar faces. However, it remains unknown whether familiarity affects part-based and/or holistic processing. Wang et al., Frontiers in Psychology, 6, 559 (2015), Vision Research, 157, 89-96 (2019) found both enhanced part-based and holistic processing in eye relative to mouth regions (i.e., in a region-selective manner) for own-race and own-species faces, i.e., faces with more experience. Here, we examined the role of face familiarity in eyes (part-based, region-selective) and holistic processing. Face familiarity was tested at three levels: high-familiar (faces of students from the same department and the same class who attended almost all courses together), low-familiar (faces of students from the same department but different classes who attended some courses together), and unfamiliar (faces of schoolmates from different departments who seldom attended the same courses). Using the old/new task in Experiment 1, we found that participants recognized eyes of high-familiar faces better than low-familiar and unfamiliar ones, while similar performance was observed for mouths, indicating a region-selective, eyes familiarity effect. Using the "Perceptual field" paradigm in Experiment 2, we observed a stronger inversion effect for high-familiar faces, a weaker inversion effect for low-familiar faces, but a non-significant inversion effect for unfamiliar faces, indicating that face familiarity plays a role in holistic processing. Taken together, our results suggest that familiarity, like other experience-based variables (e.g., race and species), can improve both eye processing and holistic processing.

Multiple latent variables but functionally dependent output mappings underlying the recognition of own- and other-race faces for Chinese individuals: Evidence from state-trace analysis

To explore the number of latent variables underlying recognition of own- and other-race faces for Chinese observers, we conducted a study-recognition task where orientation, stimuli type, and duration were manipulated in the study phase and applied state trace analysis as a statistic method. Results showed that each state trace plot on each pair of stimuli types matched a single monotonic curve when stimuli type was set to state factor, but separate curves between face and non-face showed up when the state factor was orientation. The results implied that at least two latent variables affected recognition performance in the inversion paradigm. Besides, the unidimensional structure between own- and other-race faces regardless of the state factor suggested that Chinese participants used the same recognition mechanism for unfamiliar own- and other-race faces in the inversion paradigm.

The Problem of Coordination and the Pursuit of Structural Constraints in Psychology

Paul Meehl's famous critique detailed many of the problematic practices and conceptual confusions that stand in the way of meaningful theoretical progress in psychological science. By integrating many of Meehl's points, we argue that one of the reasons for the slow progress in psychology is the failure to acknowledge the problem of coordination. This problem arises whenever we attempt to measure quantities that are not directly observable but can be inferred from observable variables. The solution to this problem is far from trivial, as demonstrated by a historical analysis of thermometry. The key challenge is the specification of a functional relationship between theoretical concepts and observations. As we demonstrate, empirical means alone cannot determine this relationship. In the case of psychology, the problem of coordination has dramatic implications in the sense that it severely constrains our ability to make meaningful theoretical claims. We discuss several examples and outline some of the solutions that are currently available.

Fleeting Perceptual Experience and the Possibility of Recalling Without Seeing

We explore an intensely debated problem in neuroscience, psychology and philosophy: the degree to which the "phenomenological consciousness" of the experience of a stimulus is separable from the "access consciousness" of its reportability. Specifically, it has been proposed that these two measures are dissociated from one another in one, or both directions. However, even if it was agreed that reportability and experience were doubly dissociated, the limits of dissociation logic mean we would not be able to conclusively separate the cognitive processes underlying the two. We take advantage of computational modelling and recent advances in state-trace analysis to assess this dissociation in an attentional/experiential blink paradigm. These advances in state-trace analysis make use of Bayesian statistics to quantify the evidence for and against a dissociation. Further evidence is obtained by linking our finding to a prominent model of the attentional blink - the Simultaneous Type/Serial Token model. Our results show evidence for a dissociation between experience and reportability, whereby participants appear able to encode stimuli into working memory with little, if any, conscious experience of them. This raises the possibility of a phenomenon that might be called sight-blind recall, which we discuss in the context of the current experience/reportability debate.

Decomposing the composite face effect: Evidence for non-holistic processing based on the ex-Gaussian distribution

Composite faces fuse the top and bottom halves from two different faces to create a powerful illusion of a novel face. It has been argued that composite faces are processed holistically, namely that the constituent face parts are perceived as a template, rather than independent features. This study sought to uncover the locus of the composite face effect by relating its empirical reaction time distributions to theoretical ex-Gaussian parameters. The results showed that the composite face effect for unfamiliar (Experiment 1) and familiar (Experiment 2) faces is generated by pure changes in the exponential component of the ex-Gaussian distribution. This held true for both partial and complete design measures. The exponential component has been attributed to working memory and attentional processes. The results suggest the involvement of attentional and working memory processes in the composite face effect and in the perception of faces in general. They cast doubts on the holistic nature of face processing. The results also provide important constraints on future computational theories of the effect.

A test of two processes: The effect of training on deductive and inductive reasoning

Dual-process theories posit that separate kinds of intuitive (Type 1) and reflective (Type 2) processes contribute to reasoning. Under this view, inductive judgments are more heavily influenced by Type 1 processing, and deductive judgments are more strongly influenced by Type 2 processing. Alternatively, single-process theories propose that both types of judgments are based on a common form of assessment. The competing accounts were respectively instantiated as two-dimensional and one-dimensional signal detection models, and their predictions were tested against specifically targeted novel data using signed difference analysis. In two experiments, participants evaluated valid and invalid arguments, under induction or deduction instructions. Arguments varied in believability and type of conditional argument structure. Additionally, we used logic training to strengthen Type 2 processing in deduction (Experiments 1 & 2) and belief training to strengthen Type 1 processing in induction (Experiment 2). The logic training successfully improved validity-discrimination, and differential effects on induction and deduction judgments were evident in Experiment 2. While such effects are consistent with popular dual-process accounts, crucially, a one-dimensional model successfully accounted for the results. We also demonstrate that the one-dimensional model is psychologically interpretable, with the model parameters varying sensibly across conditions. We argue that single-process accounts have been prematurely discounted, and formal modeling approaches are important for theoretical progress in the reasoning field.

A hierarchical Bayesian state trace analysis for assessing monotonicity while factoring out subject, item, and trial level dependencies

State trace analyses assess the latent dimensionality of a cognitive process by asking whether the means of two dependent variables conform to a monotonic function across a set of conditions. Using an assumption of independence between the measures, recently proposed statistical tests address bivariate measurement error, allowing both frequentist and Bayesian analyses of monotonicity (e.g., Davis-Stober, Morey, Gretton, & Heathcote, 2016; Kalish, Dunn, Burdakov, & Sysoev, 2016). However, inference can be biased by unacknowledged dependencies between measures, particularly when the data are insufficient to overwhelm an incorrect prior assumption of independence. To address this limitation, we developed a hierarchical Bayesian model that explicitly models the separate roles of subject, item, and trial-level dependencies between two measures. Assessment of monotonicity is then performed by fitting separate models that do or do not allow a non-monotonic relation between the condition effects (i.e., same vs. different rank orders). The Widely Applicable Information Criterion (WAIC) and Pseudo Bayesian Model Averaging - cross validation measures of model fit - are used for model comparison, providing an inferential conclusion regarding the dimensionality of the latent psychological space. We validated this new state trace analysis technique using model recovery simulation studies, which assumed different ground truths regarding monotonicity and the direction/magnitude of the subject- and trial-level dependence. We also provide an example application of this new technique to a visual object learning study that compared performance on a visual retrieval task (forced choice part recognition) versus a verbal retrieval task (cued recall).

Due Process in Dual Process: Model-Recovery Simulations of Decision-Bound Strategy Analysis in Category Learning

Behavioral evidence for the COVIS dual-process model of category learning has been widely reported in over a hundred publications (Ashby & Valentin, ). It is generally accepted that the validity of such evidence depends on the accurate identification of individual participants' categorization strategies, a task that usually falls to Decision Bound analysis (Maddox & Ashby, ). Here, we examine the accuracy of this analysis in a series of model-recovery simulations. In Simulation 1, over a third of simulated participants using an Explicit (conjunctive) strategy were misidentified as using a Procedural strategy. In Simulation 2, nearly all simulated participants using a Procedural strategy were misidentified as using an Explicit strategy. In Simulation 3, we re-examined a recently reported COVIS-supporting dissociation (Smith et al., ) and found that these misidentification errors permit an alternative, single-process, explanation of the results. Implications for due process in the future evaluation of dual-process theories, including recommendations for future practice, are discussed.

Comparing the role of selective and divided attention in the composite face effect: Insights from Attention Operating Characteristic (AOC) plots and cross-contingency correlations

Composite faces combine the top half of one face with the bottom half of another to create a compelling illusion of a new face. Evidence for holistic processing with composite faces comes primarily from a matching procedure in a selective attention task. In the present study, a dual-task approach has been employed to study whether composite faces reflect genuine holistic (i.e., fusion of parts) or non-holistic processing strategies (i.e., switching, resource sharing). This has been accomplished by applying the Attention Operation Characteristic methodology (AOC, Sperling & Melchner, 1978a, 1978b) and cross-contingency correlations (Bonnel & Prinzmetal, 1998) to composite faces. Overall, the results converged on the following conclusions: (a) observers can voluntarily allocate differential amounts of attention to the top and bottom parts in both spatially aligned and misaligned composite faces, (b) the interaction between composite face halves is due to attentional limitations, not due to switching or fusion strategies, and (c) the processing of aligned and misaligned composite faces is quantitatively and qualitatively similar. Taken together, these results challenge the holistic interpretation of the composite face illusion.

Feedback can be superior to observational training for both rule-based and information-integration category structures

The effects of two different types of training on rule-based and information-integration category learning were investigated in two experiments. In observational training, a category label is presented, followed by an example of that category and the participant's response. In feedback training, the stimulus is presented, and the participant assigns it to a category and then receives feedback about the accuracy of that decision. Ashby, Maddox, and Bohil (2002. Observational versus feedback training in rule-based and information-integration category learning. Memory & Cognition, 30, 666–677) reported that feedback training was superior to observational training when learning information-integration category structures, but that training type had little effect on the acquisition of rule-based category structures. These results were argued to support the COVIS (competition between verbal and implicit systems) dual-process account of category learning. However, a number of nonessential differences between their rule-based and information-integration conditions complicate interpretation of these findings. Experiment 1 controlled between-category structures for participant error rates, category separation, and the number of stimulus dimensions relevant to the categorization. Under these more controlled conditions, rule-based and information-integration category structures both benefited from feedback training to a similar degree. Experiment 2 maintained this difference in training type when learning a rule-based category that had otherwise been matched, in terms of category overlap and overall performance, with the rule-based categories used in Ashby et al. These results indicate that differences in dimensionality between the category structures in Ashby et al. is a more likely explanation for the interaction between training type and category structure than the dual-system explanation that they offered.

Order short-term memory is not impaired in dyslexia and does not affect orthographic learning

This article reports two studies that investigate short-term memory (STM) deficits in dyslexic children and explores the relationship between STM and reading acquisition. In the first experiment, 36 dyslexic children and 61 control children performed an item STM task and a serial order STM task. The results of this experiment show that dyslexic children do not suffer from a specific serial order STM deficit. In addition, the results demonstrate that phonological processing skills are as closely related to both item STM and serial order STM. However, non-verbal intelligence was more strongly involved in serial order STM than in item STM. In the second experiment, the same two STM tasks were administered and reading acquisition was assessed by measuring orthographic learning in a group of 188 children. The results of this study show that orthographic learning is exclusively related to item STM and not to order STM. It is concluded that serial order STM is not the right place to look for a causal explanation of reading disability, nor for differences in word reading acquisition.

A meta-analysis and review of holistic face processing

The concept of holistic processing is a cornerstone of face recognition research, yet central questions related to holistic processing remain unanswered, and debates have thus far failed to reach a resolution despite accumulating empirical evidence. We argue that a considerable source of confusion in this literature stems from a methodological problem. Specifically, 2 measures of holistic processing based on the composite paradigm (complete design and partial design) are used in the literature, but they often lead to qualitatively different results. First, we present a comprehensive review of the work that directly compares the 2 designs, and which clearly favors the complete design over the partial design. Second, we report a meta-analysis of holistic face processing according to both designs and use this as further evidence for one design over the other. The meta-analysis effect size of holistic processing in the complete design is nearly 3 times that of the partial design. Effect sizes were not correlated between measures, consistent with the suggestion that they do not measure the same thing. Our meta-analysis also examines the correlation between conditions in the complete design of the composite task, and suggests that in an individual differences context, little is gained by including a misaligned baseline. Finally, we offer a comprehensive review of the state of knowledge about holistic processing based on evidence gathered from the measure we favor based on the 1st sections of our review-the complete design-and outline outstanding research questions in that new context.

Explaining the face-inversion effect: the face-scheme incompatibility (FSI) model

The face-inversion effect (FIE) can be viewed as being based on two kinds of findings. According to the face(UI) effect, perception and recognition are better for faces presented upright (U) than for faces presented inverted (I). According to the face/object(UI) effect, inversion impairs the processing of faces more than the processing of nonfacial objects (e.g., buildings or cars). Part I of this article focuses on the face(UI) effect and the configural-processing hypothesis, which is considered the most popular explanatory hypothesis of the FIE. In this hypothesis, it is proposed that inversion impairs the processing of configural information (the spatial relations between features) but hardly (if at all) impairs the processing of featural information (e.g., eyes, nose, and mouth). Part II of the article starts from the conclusion reached in part I, that the configural-processing hypothesis has not succeeded in explaining a substantial number of the findings and in resolving certain theoretical problems. The part then goes on to outline a new alternative model, the face-scheme incompatibility (FSI) model, which contends with these theoretical problems, accounts for the configural-processing hypothesis, succeeds in explaining a considerable portion of the empirical findings related to the face(UI) effect, and proposes a relatively new research program on the concept of the face scheme. The basic assumption of the FSI model is that schemes and prototypes are involved in processing a visual stimulus of a face and in transforming it to a "meaning-bearing" face, and that different schemes are involved if the face is presented upright or inverted.

When Intuition Fails to Align with Data: A Reply to

Holistic processing, a hallmark of face perception, is often measured in the so-called composite paradigm, in which participants are asked to match part of a stimulus while ignoring another part. In prior work, we recommended against the use of one version of the composite task we call the partial design, on the basis of confounds with response biases. Rossion wrote a lengthy piece that reviews the work that he has published using this design, raising a large number of criticisms, both about an alternative measure of holistic processing that we have used and advocated (which we call the complete design) and about our work in general. In this reply, we have limited our discussion to those issues that would be relevant to a researcher looking to decide which version of this composite paradigm to use, as we doubt a comprehensive reply would be of significant interest outside a very small circle.

Using state-trace analysis to dissociate the functions of the human hippocampus and perirhinal cortex in recognition memory

A recurring issue in neuroscience concerns evidence as to whether two or more brain regions implement qualitatively different functions. Here we introduce the application of state-trace analysis to measures of neural activity, illustrating how this analysis can furnish compelling evidence for qualitatively different functions, even when the precise "neurometric" mapping between function and brain measure is unknown. In doing so, we address a long-standing debate about the brain systems supporting human memory: whether the hippocampus and the perirhinal cortex, two key components of the medial temporal lobe memory system, provide qualitatively different contributions to recognition memory. An alternative account has been that both regions support a single shared function, such as memory strength, with the apparent dissociations obtained by previous neuroimaging studies merely reflecting different, nonlinear neurometric mappings across regions. To adjudicate between these scenarios, we analyze intracranial electroencephalographic data obtained directly from human hippocampus and perirhinal cortex during a recognition paradigm and apply state-trace analysis to responses evoked by the retrieval cue as a function of different types of memory judgment. Assuming only that the neurometric mapping in each region is monotonic, any unidimensional theory (such as the memory-strength account) will produce a monotonic state trace. Critically, results showed a nonmonotonic state trace; that is, activity levels in the two regions did not show the same relative ordering across memory conditions. This nonmonotonic state trace demonstrates that there are at least two different functions implemented across the hippocampus and perirhinal cortex, allowing formal rejection of a single-process account of medial temporal lobe contributions to recognition memory.

An R package for state-trace analysis

State-trace analysis (Bamber, Journal of Mathematical Psychology, 19, 137-181, 1979) is a graphical analysis that can determine whether one or more than one latent variable mediates an apparent dissociation between the effects of two experimental manipulations. State-trace analysis makes only ordinal assumptions and so, is not confounded by range effects that plague alternative methods, especially when performance is measured on a bounded scale (such as accuracy). We describe and illustrate the application of a freely available GUI driven package, StateTrace, for the R language. StateTrace automates many aspects of a state-trace analysis of accuracy and other binary response data, including customizable graphics and the efficient management of computationally intensive Bayesian methods for quantifying evidence about the outcomes of a state-trace experiment, developed by Prince, Brown, and Heathcote (Psychological Methods, 17, 78-99, 2012).

The dimensionality of perceptual category learning: a state-trace analysis

State-trace analysis was used to investigate the effect of concurrent working memory load on perceptual category learning. Initial reanalysis of Zeithamova and Maddox (2006, Experiment 1) revealed an apparently two-dimensional state-trace plot consistent with a dual-system interpretation of category learning. However, three modified replications of the original experiment found evidence of a single resource underlying the learning of both rule-based and information integration category structures. Follow-up analyses of the Zeithamova and Maddox data, restricted to only those participants who had learned the category task and performed the concurrent working memory task adequately, revealed a one-dimensional plot consistent with a single-resource interpretation and the results of the three new experiments. The results highlight the potential of state-trace analysis in furthering our understanding of the mechanisms underlying category learning.

Inverted faces are (eventually) processed holistically

Face inversion effects are used as evidence that faces are processed differently from objects. Nevertheless, there is debate about whether processing differences between upright and inverted faces are qualitative or quantitative. We present two experiments comparing holistic processing of upright and inverted faces within the composite task, which requires participants to match one half of a test face while ignoring irrelevant variation in the other half of the test face. Inversion reduced overall performance but led to the same qualitative pattern of results as observed for upright faces (Experiment 1). However, longer presentation times were required to observe holistic effects for inverted compared to upright faces (Experiment 2). These results suggest that both upright and inverted faces are processed holistically, but inversion reduces overall processing efficiency.

Representational explanations of "process" dissociations in recognition: the DRYAD theory of aging and memory judgments

It is widely assumed that older adults suffer a deficit in the psychological processes that underlie remembering of contextual or source information. This conclusion is based in large part on empirical interactions, including disordinal ones, that reveal differential effects of manipulations of memory strength on recognition in young and old subjects. This article lays out an alternative theory that takes as a starting point the overwhelming evidence from the psychometric literature that the effects of age on memory share a single mediating influence. Thus, the theory assumes no differences between younger and older subjects other than a global difference in memory fidelity--that is, the older subjects are presumed to have less valid representations of events and objects than are young subjects. The theory is articulated through 3 major assumptions and implemented in a computational model, DRYAD, to simulate fundamental results in the literature on aging and recognition, including the very interactions taken to imply selective impairment in older people. The theoretical perspective presented here allows for a critical examination of the widely held belief that aging entails the selective disruption of particular memory processes.

Visual Expertise with Pictures of Cars Correlates with RT Magnitude of the Car Inversion Effect

In their seminal study Diamond and Carey (1986, Journal of Experimental Psychology: General115 107–117) found a larger inversion effect for dog pictures in dog experts than novices, supporting a role of visual expertise in the observation of particularly large inversion effects for faces. However, subsequent studies have provided mixed results, and very few have compared the inversion effects for faces and familiar non-face object categories. Here we tested the effect of inversion on faces and cars in car experts and novices, using a delayed matching task across viewpoint changes. Inversion affected accuracy much more for pictures of faces than of cars for both groups, with no interaction between expertise and category. However, for car experts only there was a significant correlation between the magnitude of the inversion cost in RT for car pictures and the level of expertise as measured in an independent task. These observations support the view that the particularly large inversion effect found for faces is related to expert visual processes which can be at least partially recruited to process other non-face object categories.

Beyond the Null Ritual

Rituals shape many aspects of our lives, and they are no less common in scientific research than elsewhere. One that figures prominently in hypothesis testing is the null ritual, the pitting of hypotheses against chance. Although known to be problematic, this practice is still widely used. One way to resist the lure of the null ritual is to increase the precision of theories by casting them as formal models. These can be tested against each other, instead of against chance, which in turn enables a researcher to decide between competing theories based on quantitative measures. This article gives an overview of the advantages of modeling, describes research that is based on it, outlines the difficulties associated with model testing, and summarizes some of the solutions for dealing with these difficulties. Pointers to resources for teaching modeling in university classes are provided.

On facial expertise: processing strategies of twins' parents

Parents of monozygotic twins typically learn to recognise their own children and also to tell them apart on photographs. However, it is unknown whether such exemplar expertise can be generalised to unfamiliar faces of equal similarity (ie other twins). In the present study, parents of monozygotic twins were compared to 'control' parents whose children were non-twin siblings. In a same/different task with familiar and unfamiliar twin faces as stimuli, twins' parents were faster than control parents in distinguishing their own children, but slower when distinguishing unfamiliar twin faces. These unexpected findings can be interpreted as a generalisation of a habitual perceptual strategy that is efficient only with familiar face exemplars. When pictures of the twins' faces were inverted by 180degrees, the typical inversion costs for familiar faces were observed, but the twins' parents recognised unfamiliar twins' faces better when these were inverted than when upright. This inverted inversion effect could be caused by the high similarity of the face pairs as well as by experience with familiar faces of equally high similarity. We conclude that the facial expertise of twins' parents is idiosyncratic to their own children and not based on an enhanced general facial expertise.

Dimensions in data: testing psychological models using state-trace analysis

Cognitive science is replete with fertile and forceful debates about the need for one or more underlying mental processes or systems to explain empirical observations. Such debates can be found in many areas, including learning, memory, categorization, reasoning and decision-making. Multiple-process models are often advanced on the basis of dissociations in data. We argue and illustrate that using dissociation logic to draw conclusions about the dimensionality of data is flawed. We propose that a more widespread adoption of 'state-trace analysis'--an approach that overcomes these flaws--could lead to a re-evaluation of the need for multiple-process models and to a re-appraisal of how these models should be formulated and tested.

Fluency misattribution and visual hindsight bias

We tested a fluency-misattribution theory of visual hindsight bias, and examined how perceptual and conceptual fluency contribute to the bias. In Experiment 1a observers identified celebrity faces that began blurred and then clarified (Forward baseline), or indicated when faces that began clear and then blurred were no longer recognisable (Backward baseline). In surprise memory tests that followed, observers adjusted the degree of blur of each face to match what the faces looked like when identified in the corresponding baseline condition. Hindsight bias was observed in the Forward condition: During the memory test observers adjusted the faces to be more blurry than when originally identified during baseline. These same observers did not show hindsight bias in the Backward condition: Here, they adjusted faces to the exact blur level at which they identified the faces during baseline. Experiment 1b tested a combined condition in which faces were viewed in a Forward progression at baseline but in a Backward progression at test. Hindsight bias was observed in this condition but was significantly less than the bias observed in the Experiment 1a Forward condition. Experiments 1a and 1b provide support for the fluency-misattribution account of visual hindsight bias: When observers are made aware of why fluency has been enhanced (i.e., in the Backward condition) they are better able to discount it, and as a result show reduced or no hindsight bias. In Experiment 2, observers viewed faces in a Forward progression at baseline and then in a Forward upright or inverted progression at test. Hindsight bias occurred in both conditions, but was greater for upright than inverted faces. We conclude that both conceptual and perceptual fluency contribute to visual hindsight bias.

The representation of multiplication facts: Developmental changes in the problem size, five, and tie effects

In this study, we investigated the development of basic effects that have been found in single-digit multiplication arithmetic: the problem size, five, and tie effects. Participants (9-, 10-, and 11-year-olds and adults) performed a production task on simple multiplication. The procedure replicated study [Canadian Journal of Psychology, Vol. 39, pp. 338-366], but the results show that the gradual decrease of the problem size effect ends in sixth grade. We report analyses on raw latencies and state trace analyses that take into account reaction time scaling as a function of age. The results show that 11-year-olds do not differ significantly from adults on any of the three effects. Before 11 years of age, interesting developmental changes occur.

Holistic processing unites face parts across time

When complementary halves of different familiar faces are combined into a new face, there is interference in the identification of either half. This "composite face effect" has been taken as strong evidence that faces are processed holistically. Here, we demonstrate that this effect can persist when the two parts of a face are separated by up to 80 ms of visual noise, showing that the parts of a face interact not only spatially but also temporally. We suggest that the processing underlying robust identification accepts an accumulation of evidence over time.

How Many Dimensions Underlie Judgments of Learning and Recall? Evidence From State-Trace Methodology

The authors used state-trace methodology to investigate whether a single dimension (e.g., strength) is sufficient to account for recall and judgments of learning (JOLs) or whether multiple dimensions (e.g., intrinsic and extrinsic factors) are needed. The authors separately manipulated the independent variables of intrinsic and extrinsic cues, determining their state traces for recall and JOLs. In contrast to the supposition that intrinsic cues have similar effects on both recall and JOLs whereas extrinsic cues affect JOLs less strongly than recall (i.e., 2 dimensions underlying recall and JOLs), the authors found repeated support for the sufficiency of a single dimension for both recall and JOLs (not only immediate JOLs but also delayed JOLs) across a variety of intrinsic and extrinsic cues.