Valid distinctions between conscious and unconscious perception?

In this commentary, we discuss the strengths and limitations of Snodgrass, Bernat, and Shevrin's (2004) theory of unconscious perception. Our commentary centers on the value of signal detection theory (SDT) to understanding the unconscious perception controversy, a value that Snodgrass et al. for the most part agree with (i.e., that most approaches to studying unconscious perception are invalid because they have confounded the criterion for detection with the criterion for awareness). However, we believe that their model relies on a somewhat restricted application of SDT. We discuss how SDTcan be better applied to provide the necessary tests to validate their model.     

Disambiguating conscious and unconscious influences: do exclusion paradigms demonstrate unconscious perception?

Does exclusion failure--responding with previously presented words despite instructions to avoid doing so--demonstrate unconscious influences? This article examines exclusion-based evidence for unconscious perception. I propose an alternative signal detection theory (SDT) framework that can account for exclusion failure and ostensibly convergent qualitative differences without positing additional unconscious perceptual mechanisms. In the proposed SDT model, exclusion failure is a criterion artifact, similar to classic SDT-based critiques of subjective threshold approaches. However, it is suggested that exclusion approaches do demonstrate that response strategies are applied only to above-criterion stimuli and thereby illustrate important qualitative differences between two conscious processes: phenomenal awareness itself and higher-order (i.e., metacognitive) decision processes.     

Do young and older adults rely on different processes in source memory tasks? A neuropsychological study

Source memory has consistently been associated with prefrontal function in both normal and clinical populations. Nevertheless, the exact contribution of this brain region to source memory remains uncertain, and evidence suggests that processes used by young and older adults may differ. The authors explored the extent to which scores on composite measures of neuropsychological tests of frontal and medial temporal function differentially predicted the performance of young and older adults on source memory tasks. Results indicated that a frontal composite measure, consistently associated with source memory performance in older adults, was unrelated to source memory in young adults, although it was sensitive to a demanding working memory task. The memory composite score, however, predicted performance in the young group. In addition, item and source memory were correlated in young but not older people. Findings are discussed in terms of age-related differences in working memory and executive functions, and differential binding processes necessary for item and source memory. The requirement to integrate item and source information at encoding appears to place greater demands on executive or working memory processes in older adults than in younger adults.     

Recognition and lexical decision without detection: unconscious perception?

Stimulus detection and concurrent measures of stimulus recognition were compared to establish whether perception occurs in the absence of detection. The target stimuli were familiar words (Experiments 1 and 2), nonwords (Experiment 3), or both words and nonwords (Experiment 4). On each trial, either a stimulus or a blank field was presented. Ss first decided whether a stimulus had been presented and then made either a forced-choice recognition decision (Experiments 1, 2, and 3) or a lexical decision (Experiment 4). Both words and nonwords were recognized and discriminated following correct detections (i.e., hits). However, in the absence of stimulus detection (i.e., misses), only words were recognized or discriminated. These qualitatively different patterns of results following hits and misses for words and nonwords suggest that stimulus detection may provide an adequate measure of conscious awareness.     

Do multiplication and division strategies rely on executive and phonological working memory resources?

The role of executive and phonological working memory resources in simple arithmetic was investigated in two experiments. Participants had to solve simple multiplication problems (e.g., 4 x 8; Experiment 1) or simple division problems (e.g., 42 / 7; Experiment 2) under no-load, phonological-load, and executive-load conditions. The choice/no-choice method was used to investigate strategy execution and strategy selection independently. Results for strategy execution showed that executive working memory resources were involved in direct memory retrieval of both multiplication and division facts. Executive working memory resources were also involved in the use of nonretrieval strategies. Phonological working memory resources, on the other hand, tended to be involved in nonretrieval strategies only. Results for strategy selection showed no effects of working memory load. Finally, correlation analyses showed that both strategy execution and strategy selection correlated with individual-difference variables, such as gender, math anxiety, associative strength, calculator use, arithmetic skill, and math experience.     

Do apes and monkeys rely upon conceptual reversibility?

The ability to seriate nesting cups as a sensorimotor task has posed interesting questions for cognitive scientists. Greenfield et al. [(1972) Cognit Psychol 3:291–310] found parallels between children's combinatorial activity with nesting cups and patterns of phonological and grammatical constructions. The parallels suggested the possibility of a neurally based developmental homology between language and instrumental action [Greenfield (1991) Behav Brain Sci 14:531–595]. Children who predominantly used subassembly, a hierarchical method of combining cups, succeeded at seriating nesting cups more often than those who did not. Greenfield and others [e.g., Piaget and Inhelder (1969) The psychology of the child. Basic Books, New York; DeLoache et al. (1985) Child Dev 56:928–939] argued that success in seriation reflects the child's growing recognition of a reversible relationship: a particular element in a series is conceived of as being smaller than the previous element and larger than the subsequent element. But is a concept of reversibility or a hierarchical form of object manipulation necessary to seriate cups? In this article, we review studies with very young children and nonhuman primates to determine how individuals that do not evidence conceptual reversibility manage the seriation task. We argue that the development of skill in seriation is experientially, rather than conceptually, driven and that it may be unnecessary to link seriation with cognitive conceptions of reversibility or linguistic capacities. Rather, in ordering a set of objects by size, perceptual-motor learning may enable contemplative refinement. Accepted after revision: 10 September 2001 Electronic Publication     

Visual masking and unconscious processing: differences between backward and simultaneous masking?

Visual masking procedures are considered to have great potential for studying information processing that occurs outside of consciousness. Unfortunately, effects that indicate processing of masked word stimuli have been both difficult to obtain and, once obtained, difficult to replicate. The present seven experiments failed to obtain an effect of lexicality (word vs. nonword targets) on detection that was recently reported by Doyle and Leach (1988). Whereas Doyle and Leach had used backward binocular masking, most of the present experiments used simultaneous dichoptic masking. Doyle (1990) recently suggested that the effect of lexicality on detection (coupled with an effect of knowledge of results, which was also not obtained in the present research) could explain why Greenwald, Klinger, and Liu (1989) found no evidence for detectability of masked words that were nevertheless analyzed semantically. The differences of the present findings from those of Doyle and Leach (1988) not only confirm the uncertainty of generalizing across masking procedures, but also indicate that Greenwald et al.'s "detectionless processing" interpretation remains viable.     

Unconscious creativity: When can unconscious thought outperform conscious thought?

Recent research suggests that unconscious thought is superior to conscious thought in many cognitive domains. In this article, we show that the duration of unconscious thought has an inverted-U shaped relationship with creativity performance. Unconscious thought is, thus, unlikely to provide creative advantage over conscious thought when deliberation duration is either short or long. However, when deliberation duration is of a moderate length, the creative output of unconscious thought surpasses that of conscious thought. Furthermore, the superiority of unconscious thought pertains only to the novelty dimension of creativity, but not the appropriateness dimension. These findings not only shed light on the powers and limits of unconscious thought but also illuminate the importance of calibration in utilizing unconscious thought to boost creativity.     

Does opposition logic provide evidence for conscious and unconscious processes in artificial grammar learning?

The question of whether studies of human learning provide evidence for distinct conscious and unconscious influences remains as controversial today as ever. Much of this controversy arises from the use of the logic of dissociation. The controversy has prompted the use of an alternative approach that places conscious and unconscious influences on memory retrieval in opposition. Here we ask whether evidence acquired via the logic of opposition requires a dual-process account or whether it can be accommodated within a single similarity-based account. We report simulations using a simple neural network model of two artificial grammar learning experiments reported by that dissociated conscious and unconscious influences on classification. The simulations demonstrate that opposition logic is insufficient to distinguish between single- and multiple-system models.     

Do confusing information and egocentric instructions influence perception?

In an investigation of psychological differentiation, Witkin's personality dimension, 12 field-dependent and 12 field-independent students were selected from a population of college men in summerschool based on their Embedded Figures Test scores. They were assigned to conditions, given egocentric or gravitational instructions, and provided clarified or obscuring feedback about their performance on the Rod and Frame Test. Although instructions had no effect, students with clarified feedback performed better than those whose feedback was confusing. Field-independent men had less difficulty with the confusing feedback than did field-dependent men.     

Do dyslexia and stuttering share a processing deficit?

This study assessed the prevalence of childhood stuttering in adults with dyslexia (AWD) and the prevalence of dyslexia in adults who stutter (AWS). In addition, the linguistic profiles of 50 AWD, 30 AWS and 84 neurotypical adults were measured. We found that 17 out of 50 AWD (34 %) reported stuttering during childhood compared to 1 % of the neurotypical population. This was moderated by the severity of dyslexia: People with mild dyslexia showed a lower prevalence rate (15 %) of childhood stuttering than those with severe dyslexia (47 %). In addition, we observed that 50 % of the AWS (n = 30) fulfilled the diagnostic criteria of dyslexia, even though they had never been diagnosed as dyslexic. Compared to neurotypical adults, phonological working memory, awareness, and retrieval were similarly reduced in AWS and AWD. The findings supports the view that stuttering and dyslexia may share a phonological deficit.     

The impact of emotion on perception: bias or enhanced processing?

Recent studies have shown that emotionally significant stimuli are often better identified than neutral stimuli. It is not clear, however, whether these results are due to enhanced perceptual processing or to a bias favoring the identification of emotionally significant stimuli over neutral stimuli. The present study used a two-alternative forced-choice perceptual identification task to disentangle the effects of bias and enhanced processing. We found that emotionally significant targets were better identified than neutral targets. In contrast, the emotional significance of the foil alternative had no effect on performance. The present results support the hypothesis that perceptual encoding of emotionally significant stimuli is enhanced.     

Do parents and children know each other? A study about agreement on personality within families

The relationships between self-report and observer-rating versions of personality questionnaires within families in the Spanish cultural context were studied. In the first sample, 336 couples rated the personality of one of their children. The children also assessed their own personality. Goldberg's adjectives were administered. In the second sample, 120 university students rated the personality of their parents. Both parents also assessed their own personality. In this case, Goldberg's adjectives and the NEO-PI-R were administered. Results replicate the level of agreement found in other cultural contexts. Correlations were around .40, and the effect size of the mean differences was not large. Children were more accurate than parents, larger agreement coefficients were found for the NEO-PI-R than for Goldberg's adjectives in Sample 2, especially for the Openness factor, and no substantial role for the sex variable was found in either sample. Implications and limitations of the present study are discussed.     

Do sex and perception of immediate stress affect optimism?

The purpose was to assess differences in mean optimism scores of men and women of low immediate stress (23 men, 28 women) and high immediate stress (11 men, 34 women). Using factorial analysis of variance, mean differences on the Coping Resources Inventory, Cognitive Domain, were not significant for sex, immediate stress, or their interaction.     

Does evaluative learning rely on the perception of contingency?: manipulating contingency and US density during evaluative conditioning

An experiment is reported studying the impact of objective contingency and contingency judgments on cross-modal evaluative conditioning (EC). Both contingency judgments and evaluative responses were measured after a contingency learning task in which previously neutral sounds served as either weak or strong predictors of affective pictures. Experimental manipulations of contingency and US density were shown to affect contingency judgments. Stronger contingencies were perceived with high contingency and with low US density. The contingency learning task also produced a reliable EC effect. The magnitude of this effect was influenced by an interaction of statistical contingency and US density. Furthermore, the magnitude of EC was correlated with the subjective contingency judgments. Taken together, the results imply that propositional knowledge about the CS-US relationship, as reflected in contingency judgments, moderates evaluative learning. The data are discussed with respect to different accounts of EC.     

Do endogenous and exogenous action control compete for perception?

Human actions are guided either by endogenous action plans or by external stimuli in the environment. These two types of action control seem to be mediated by neurophysiologically and functionally distinct systems that interfere if an endogenously planned action suddenly has to be performed in response to an exogenous stimulus. In this case, the endogenous representation has to be deactivated first to give way to the exogenous system. Here we show that interference of endogenous and exogenous action control is not limited to motor-related aspects but also affects the perception of action-related stimuli. Participants associated two actions with contingent sensory effects in learning blocks. In subsequent test blocks, preparing one of these actions specifically impaired responding to the associated effect in an exogenous speeded detection task, yielding a blindness-like effect for arbitrary, learned action effects. In accordance with the theory of event coding, this finding suggests that action planning influences perception even in the absence of any physical similarities between action and to-be-perceived stimuli.     

Parallel processing in visual perception and memory: What goes where and when?

This article begins with reviews of parallel processing models in the areas of visual perception and memory, pointing out kinds of information purported to be processed in each, and the overlap in the physiological substrates involved. Next, some pertinent literature having to do with the linkage between perception and memory is reviewed (e.g., visual memory for what or where), concluding that there exists a serious lack of research and knowledge of how different perceptual processes may lead to facilitated, distorted or impaired memory in different forms of storage. Some possible scenarios are presented concerning how perceptual information might be interfaced with memorial mechanisms, and some working hypotheses are considered. Finally, a new paradigm is outlined that examines the linkage between local and global perceptual processing and explicit and implicit learning. This paradigm combines the global precedence paradigm of Navon (1977; 1981) and the sequence learning paradigm of Nissen and Bullemer (1987). Convincing arguments indicate that global stimuli are mediated more quickly via one perceptual stream (the M-cell pathway), but can be processed more slowly by another (the P-cell system). Local aspects of the stimuli are exclusively mediated by the P-cell system. The results of two experiments employing iterations of stimulus sequence, in which sequence learning is possible and measurable in terms of reaction time changes over trials are presented. The second experiment indicates that information thought to be mediated by the M-cell pathway results in incidental sequential learning, while other information thought to be mediated by the P-cell pathway does not. Spatial filtering of the visual stimuli reveals that low spatial frequencies are necessary for sequence learning to occur. The issue of whether this learning is implicit or explicit is also discussed. Ideas for future research, exploring this new area of interest, are proposed. Current knowledge of perceptual and memorial deficits in special populations are considered in an attempt to identify new areas of investigation.     

Liking and response latency in teammate identification: processing delays below conscious awareness?

Success in fast-ball sports relies on many factors which interact at both movement and cognitive levels. Players must recognize their teammates and decide whether to pass the ball to create or take advantage of scoring affordances. Previous research has shown athletes can identify teammates from brief visual displays during fast-ball sports and this is related to the amount of time individuals train together. However, it is likely other factors also affect recognition and, consequently, decision making related to ball passing. The present study extended the Teammate Identification (TM-ID) paradigm to examine magnitude of liking of one's teammates in relation to response time components of TM-ID. An increase in movement time was found for identifying a swimmer who was the observer's "least liked" teammate, which suggests that processes below conscious awareness may influence the time taken for sport actions directed toward specific teammates, such as ball passing.