Philip M. Merikle

Working memory and language comprehension: A meta-analysis.

This paper presents a meta-analysis of the data from 6,179 participants in 77 studies that investigated the association between working-memory capacity and language comprehension ability. A primary goal of the meta-analysis was to compare the predictive power of the measures of working memory developed by Daneman and Carpenter (1980) with the predictive power of other measures of working memory. The results of the meta-analysis support Daneman and Carpenter’s (1980) claim that measures that tap the combined processing and storage capacity of working memory (e.g., reading span, listening span) are better predictors of comprehension than are measures that tap only the storage capacity (e.g., word span, digit span). The meta-analysis also showed that math process plus storage measures of working memory are good predictors of comprehension. Thus, the superior predictive power of the process plus storage measures is not limited to measures that involve the manipulation of words and sentences.

Using direct and indirect measures to study perception without awareness.

Many studies directed at demonstrating perception without awareness have relied on the dissociation paradigm. Although the logic underlying this paradigm is relatively straightforward, definitive results have been elusive in the absence of any general consensus as to what constitutes an adequate measure of awareness. We propose an alternative approach that involves comparisons of the relative sensitivity of comparable direct and indirect indexes of perception. The only assumption required by the proposed approach is that the sensitivity of direct discriminations to relevant conscious information is greater than or equal to the sensitivity of comparable indirect discriminations. The proposed approach is illustrated through an evaluation of Avant and Thieman’s (1985) recent claim that an indirect measure of perception based on judgments of apparent visual duration provides a more sensitive indicator of perception than does a direct measure based on forced-choice recognition. Contrary to this claim, when direct and indirect indexes are measured under comparable conditions, an indirect measure based on judgments of perceived duration provides a less sensitive index of perceptual processing than do comparable direct measures. The proposed approach provides a general conceptual/methodological framework for using the dissociation paradigm in studies directed at establishing unconscious processes.

Differential attentional guidance by unattended faces expressing positive and negative emotion

Four experiments were conducted to evaluate whether focal attention can be guided by an analysis of the emotional expression in a face. Participants searched displays of 7, 11, 15, and 19 schematic faces for the location of a unique face expressing either a positive or a negative emotion located among distractor faces expressing a neutral emotion. The slopes of the search functions for locating the negative face were shallower than the slopes of the search functions for locating the positive face (Experiments 1A and 2A). When the faces were inverted to reduce holistic face perception, the slopes of the search functions for locating positive and negative faces were not different (Experiments 1B and 2B). The results suggest that the emotional expression in a face can be perceived outside the focus of attention and can guide focal attention to the location of the face.

Priming with and without awareness

In two experiments, no evidence for perception without awareness was found in a Stroop-priming task when the threshold for detecting color-word primes was measured reliably by a forced-choice procedure. Color words and color patches were either congruent or incongruent, and no priming occurred when the words were presented at the detection threshold. However, systematic increases in the level of detection for the primes led to correlated increases in the magnitude of priming. The results provide no support for recent claims that priming is a more sensitive indicator of perceptual processing than detection based upon verbal report. A resolution to the apparent discrepancy between the present results and previously reported findings is suggested.

Perception without Awareness: Perspectives from Cognitive Psychology.

Four basic approaches that have been used to demonstrate perception without awareness are described. Each approach reflects one of two types of experimental logic and one of two possible methods for controlling awareness. The experimental logic has been either to demonstrate a dissociation between a measure of perception with awareness and a measure that is sensitive to perception without awareness or to demonstrate a qualitative difference between the consequences of perception with and without awareness. Awareness has been controlled either by manipulating the stimulus conditions or by instructing observers on how to distribute their attention. The experimental findings based on all four approaches lead to the same conclusion; namely, stimuli are perceived even when observers are unaware of the stimuli. This conclusion is supported by results of studies in which awareness has been assessed with either objective measures of forced-choice discriminations or measures based on verbalizations of subjective conscious experiences. Given this solid empirical support for the concept of perception without awareness, a direction for future research studies is to assess the functions of information perceived without awareness in determining what is perceived with awareness. The available evidence suggests that information perceived without awareness both biases what stimuli are perceived with awareness and influences how stimuli perceived with awareness are consciously experienced.

Not all synaesthetes are created equal: Projector versus associator synaesthetes

In synaesthesia, ordinary stimuli elicit extraordinary experiences. When grapheme-color synaesthetes view black text, each grapheme elicits a photism—a highly specific experience of color. Importantly, some synaesthetes (projectors) report experiencing their photisms in external space, whereas other synaesthetes (associators) report experiencing their photisms “in the mind’s eye.” We showed that projectors and associators can be differentiated not only by their subjective reports, but also by their performance on Stroop tasks. Digits were presented in colors that were either congruent or incongruent with the synaesthetes’ photisms. The synaesthetes named either the video colors of the digits or the colors of the photisms elicited by the digits. The results revealed systematic differences in the patterns of Stroop interference between projectors and associators. Converging evidence from first-person reports and third-person objective measures of Stroop interference establish the projector/ associator distinction as an important individual difference in grapheme-color synaesthesia.

Negative facial expression captures attention and disrupts performance

In two experiments, participants counted features of schematic faces with positive, negative, or neutral emotional expressions. In Experiment 1 it was found that counting features took longer when they were embedded in negative as opposed to positive faces. Experiment 2 replicated the results of Experiment 1 and also demonstrated that more time was required to count features of negative relative to neutral faces. However, in both experiments, when the faces were inverted to reduce holistic face perception, no differences between neutral, positive, and negative faces were observed, even though the feature information in the inverted faces was the same as in the upright faces. We suggest that, relative to neutral and positive faces, negative faces are particularly effective at capturing attention to the global face level and thereby make it difficult to count the local features of faces.

Five plus two equals yellow

In synaesthesia, ordinary stimuli elicit extraordinary experiences. For example when C., who is a digit–colour synaesthete, views black digits, each number elicits a photism — a visual experience of a specific colour. It has been proposed that synaesthetic experiences differ from imagery in their consistency, automaticity and reliance on external stimuli to induce them. Here we demonstrate that C.s photisms are both consistent and automatic, but we find that an externally presented inducing stimulus is not necessary to trigger a photism and that simply activating the concept of a digit is sufficient.

Parallels between perception without attention and perception without awareness.

Do studies of perception without awareness and studies of perception without attention address a similar underlying concept of awareness? To answer this question, we compared qualitative differences in performance across variations in stimulus quality (i.e., short vs. long prime-mask stimulus onset asynchrony) with qualitative differences in performance across variations in the direction of attention (i.e., focused vs. divided). The qualitative differences were based on three different phenomena: Stroop priming, false recognition, and exclusion failure. In all cases, variations in stimulus quality and variations in the direction of attention led to parallel findings. These results suggest that perception with and without awareness and perception with and without attention are equivalent ways of describing the same underlying process distinction.

Synaesthetic Photisms Influence Visual Perception

When C, a digit-color synaesthete, views black digits, she reports that each digit elicits a highly specific color (a photism), which is experienced as though the color was externally projected onto the digit. We evaluated this claim by assessing whether Cs photisms influenced her ability to perceive visually presented digits. C identified and localized target digits presented against backgrounds that were either congruent or incongruent with the color of her photism for the digits. The results showed that C was poorer at identifying and localizing digits on congruent than incongruent trials. Such differences in performance between congruent and incongruent trials were not found with nonsynaesthete control participants. These results suggest that Cs colored photisms influence her perception of black digits. We propose a model in which color information influences the perception of digits through reentrant pathways in the visual system.