Jennifer J. Richler

Effect size estimates: Current use, calculations, and interpretation.

The Publication Manual of the American Psychological Association (American Psychological Association, 2001, American Psychological Association, 2010) calls for the reporting of effect sizes and their confidence intervals. Estimates of effect size are useful for determining the practical or theoretical importance of an effect, the relative contributions of factors, and the power of an analysis. We surveyed articles published in 2009 and 2010 in the Journal of Experimental Psychology: General, noting the statistical analyses reported and the associated reporting of effect size estimates. Effect sizes were reported for fewer than half of the analyses; no article reported a confidence interval for an effect size. The most often reported analysis was analysis of variance, and almost half of these reports were not accompanied by effect sizes. Partial η2 was the most commonly reported effect size estimate for analysis of variance. For t tests, 2/3 of the articles did not report an associated effect size estimate; Cohens d was the most often reported. We provide a straightforward guide to understanding, selecting, calculating, and interpreting effect sizes for many types of data and to methods for calculating effect size confidence intervals and power analysis.

Holistic Processing Predicts Face Recognition

The concept of holistic processing is a cornerstone of face-recognition research. In the study reported here, we demonstrated that holistic processing predicts face-recognition abilities on the Cambridge Face Memory Test and on a perceptual face-identification task. Our findings validate a large body of work that relies on the assumption that holistic processing is related to face recognition. These findings also reconcile the study of face recognition with the perceptual-expertise work it inspired; such work links holistic processing of objects with people’s ability to individuate them. Our results differ from those of a recent study showing no link between holistic processing and face recognition. This discrepancy can be attributed to the use in prior research of a popular but flawed measure of holistic processing. Our findings salvage the central role of holistic processing in face recognition and cast doubt on a subset of the face-perception literature that relies on a problematic measure of holistic processing.

Why Does Selective Attention to Parts Fail in Face Processing

One hallmark of holistic face processing is an inability to selectively attend to 1 face part while ignoring information in another part. In 3 sequential matching experiments, the authors tested perceptual and decisional accounts of holistic processing by measuring congruency effects between cued and uncued composite face halves shown in spatially aligned or disjointed configurations. The authors found congruency effects when the top and bottom halves of the study face were spatially aligned, misaligned (Experiment 1), or adjacent to one another (Experiment 2). However, at test, congruency effects were reduced by misalignment and abolished for adjacent configurations. This suggests that manipulations at test are more influential than manipulations at study, consistent with a decisional account of holistic processing. When encoding demands for study and test faces were equated (Experiment 3), the authors observed effects of study configuration suggesting that, consistent with a perceptual explanation, encoding does influence the magnitude of holistic processing. Together, these results cannot be accounted for by current perceptual or decisional accounts of holistic processing and suggest the existence of an attention-dependent mechanism that can integrate spatially separated face parts.

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.

Holistic Processing of Faces: Perceptual and Decisional Components

Researchers have used several composite face paradigms to assess holistic processing of faces. In the selective attention paradigm, participants decide whether one face part (e.g., top) is the same as a previously seen face part. Their judgment is affected by whether the irrelevant part of the test face is the same as or different than the relevant part of the study face. This failure of selective attention implies holistic processing. However, the authors show that this task alone cannot distinguish between perceptual and decisional sources of holism. The distinction can be addressed by the complete identification paradigm, in which both face parts are judged to be same or different, combined with analyses based on general recognition theory (F. G. Ashby & J. T. Townsend, 1986). The authors used a different paradigm, sequential responses, to relate these 2 paradigms empirically and theoretically. Sequential responses produced the same results as did selective attention and complete identification. Moreover, disruptions of holistic processing by systematic misalignment of the faces corresponded with systematic and significant changes in the decisional components, but not in the perceptual components, that were extracted using general recognition theory measures. This finding suggests a significant decisional component of holistic face processing in the composite face task.

Holistic Processing of Faces Happens at a Glance

Holistic processing (HP) of faces can be inferred from failure to selectively attend to part of a face. We explored how encoding time affects HP of faces by manipulating exposure duration of the study or test face in a sequential matching composite task. HP was observed for exposure as rapid as 50 ms, and was unaffected by whether exposure of the study or test face was limited. Holistic effects emerge as soon as performance is above chance, and are not larger at rapid exposure durations. Limiting exposure at study vs. test did have differential effects on response biases at the fastest exposure durations. These findings provide key constraints for understanding mechanisms of face recognition. These results are first to demonstrate that HP of faces emerges for very briefly presented faces, and that limited perceptual encoding time affects response biases and overall level of performance but not whether faces are processed holistically.

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.

Meanings, Mechanisms, and Measures of Holistic Processing

Few concepts are more central to the study of face recognition than holistic processing. Progress toward understanding holistic processing is challenging because the term “holistic” has many meanings, with different researchers addressing different mechanisms and favoring different measures. While in principle the use of different measures should provide converging evidence for a common theoretical construct, convergence has been slow to emerge. We explore why this is the case. One challenge is that “holistic processing” is often used to describe both a theoretical construct and a measured effect, which may not have a one-to-one mapping. Progress requires more than greater precision in terminology regarding different measures of holistic processing or different hypothesized mechanisms of holistic processing. Researchers also need to be explicit about what meaning of holistic processing they are investigating so that it is clear whether different researchers are describing the same phenomenon or not. Face recognition differs from object recognition, and not all meanings of holistic processing are equally suited to help us understand that important difference.

The Vanderbilt Expertise Test reveals domain-general and domain-specific sex effects in object recognition.

Individual differences in face recognition are often contrasted with differences in object recognition using a single object category. Likewise, individual differences in perceptual expertise for a given object domain have typically been measured relative to only a single category baseline. In Experiment 1, we present a new test of object recognition, the Vanderbilt Expertise Test (VET), which is comparable in methods to the Cambridge Face Memory Task (CFMT) but uses eight different object categories. Principal component analysis reveals that the underlying structure of the VET can be largely explained by two independent factors, which demonstrate good reliability and capture interesting sex differences inherent in the VET structure. In Experiment 2, we show how the VET can be used to separate domain-specific from domain-general contributions to a standard measure of perceptual expertise. While domain-specific contributions are found for car matching for both men and women and for plane matching in men, women in this sample appear to use more domain-general strategies to match planes. In Experiment 3, we use the VET to demonstrate that holistic processing of faces predicts face recognition independently of general object recognition ability, which has a sex-specific contribution to face recognition. Overall, the results suggest that the VET is a reliable and valid measure of object recognition abilities and can measure both domain-general skills and domain-specific expertise, which were both found to depend on the sex of observers.

Perceptual Expertise as a Shift From Strategic Interference to Automatic Holistic Processing

Holistic processing was initially characterized as a unique hallmark of face perception but later was argued to be a marker of general perceptual expertise. More recently, evidence for holistic processing—measured by interference from task-irrelevant parts—was obtained in novices, raising questions for its usefulness as a test of expertise. Indeed, recent studies use the same task to make opposite claims: One group of researchers found more interference in novices than experts for Chinese characters, while another found more interference in experts than novices with objects. Offering a resolution to this paradox, our work on the perception of musical notation suggests that expert and novice interference effects represent two ends of a continuum: Interference is initially strategic and contextual but becomes more automatic as holistic processing develops with the acquisition of perceptual expertise.