New approaches to understanding unconscious processes: Implicit and explicit memory systems

Abstract

Freud viewed the unconscious as being roughly equivalent to dynamically repressed wishes, needs, and motivations. Findings from developmental psychology, cognitive psychology, psychoanalysis, and neuroscience over the past 40 years have dramatically changed our views of unconscious processes and the human mind. It is now clear that Freud's dynamic unconscious is only a minor segment of information that is processed at subsymbolic, implicit, and automatic levels. Only a fraction of this information is further processed at explicit conscious levels. Moreover, the vast majority of the information that remains nonconscious is adaptive and has major consequences for development. We examine some clinical implications of these views.     

Visual orientation in hospitalized boys with early onset conduct disorder and borderline intellectual functioning

The aim of the present study is to investigate visual orientation in hospitalized boys with severe early onset conduct disorder and borderline intellectual functioning. It is tested whether boys with the dual diagnosis have a stronger action-oriented response style to visual-cued go signals than the norm. To this end, boys with the dual diagnosis were compared with a peer control group on Posner's (1980) Posner, M. I. 1980. Orienting of attention. Quarterly Journal of Experimental Psychology, 32: 3–25. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar] visual-spatial detection test. Here, on each trial, a visual cue points either in the direction of the location of a subsequent go signal (valid cue), or points in the opposite direction away from the location of the subsequent go signal (invalid cue). Findings indicated superior orientation (a strong action-oriented response style) of children with the dual diagnosis in valid-cued trials as well as in invalid-cued trials in both the left and the right visual hemifield. Findings were controlled for attention scores on the Child Behavior Checklist -Teacher Form and IQ scores.     

The impact of Relative Prevalence on dual-target search for threat items from airport X-ray screening

The probability of target presentation in visual search tasks influences target detection performance: this is known as the prevalence effect (Wolfe et al., 2005). Additionally, searching for several targets simultaneously reduces search performance: this is known as the dual-target cost (DTC: Menneer et al., 2007). The interaction between the DTC and prevalence effect was investigated in a single study by presenting one target in dual-target search at a higher level of prevalence than the other target (Target A: 45% Prevalence; Target B: 5% Prevalence). An overall DTC was found for both RTs and response accuracy. Furthermore, there was an effect of target prevalence in dual-target search, suggesting that, when one target is presented at a higher level of prevalence than the other, both the dual-target cost and the prevalence effect contribute to decrements in performance. The implications for airport X-ray screening are discussed.     

The Questions We Left Behind: Reflections from a Teaching Theologian

Abstract : While the ordination of women made great strides in ending gender injustice for women in church‐related vocations, women also have raised other questions, specifically: the appropriate role of experience in theological discourse and moral deliberation; the displacement of advocacy by representation; and the tension between the personal and the political. Fore‐mothers leave behind these issues for their after‐daughters, as they meet challenges their fore‐mothers in the faith could hardly imagine.     

Developmental changes during childhood in single-letter acuity and its crowding by surrounding contours

Crowding refers to impaired target recognition caused by surrounding contours. We investigated the development of crowding in central vision by comparing single-letter and crowding thresholds in groups of 5-year-olds, 8-year-olds, 11-year-olds, and adults. The task was to discriminate the orientation of a Sloan letter E. Single-letter thresholds, defined as the stroke width forming the smallest discriminable E, were worse than those of adults (0.83 arcmin) at 5 years of age (1.05 arcmin) but not at older ages (8-year-olds: 0.81 arcmin; 11-year-olds: 0.78 arcmin). The maximum distances over which crowding occurred, as measured in multiples of threshold stroke width, were smaller in adults (2.83) than in the three groups of children, who did not differ from each other (5-year-olds: 7.03; 8-year-olds: 7.84; 11-year-olds: 7.13). Thus, even 11-year-olds are more affected than adults by surrounding contours despite having single-letter acuity that has been mature for several years. The stronger influence of crowding in children may be caused by immaturities in the brain areas beyond the primary visual cortex (V1) where early visual inputs are combined and may contribute to their slower reading speed.     

Amodal completion in bonobos

We trained two bonobos to discriminate among occluded, complete, and incomplete stimuli. The occluded stimulus comprised a pair of colored shapes, one of which appeared to occlude the other. The complete and incomplete stimuli involved the single shape that appeared to have been partially covered in the occluded stimulus; the complete stimulus showed the full shape, whereas the incomplete stimulus showed the same portion of the shape that was visible in the occluded stimulus. The correct response was to select the two-part occluded stimulus. Consistent with amodal completion, the bonobos committed a higher percentage of errors to the complete stimuli than to the incomplete stimuli. As well, the percentage of errors to the complete stimuli rose after repeated training with several different shapes. Extensive experience with two-dimensional images enhances amodal completion of partially occluded stimuli in bonobos.     

Attentional modulation of visual-evoked potentials by threat: investigating the effect of evolutionary relevance

In dot-probe tasks, threatening cues facilitate attention to targets and enhance the amplitude of the target P1 peak of the visual-evoked potential. While theories have suggested that evolutionarily relevant threats should obtain preferential neural processing, this has not been examined empirically. In this study we examined the effects of evolutionarily relevant (e.g. spiders and snakes) and irrelevant (e.g. knifes and syringes) threatening cues. Non-predictive threatening cues (in left or right visual field) were paired with non-threatening cues and were followed by neutral targets in the same or opposite location. The amplitude of the target P1 was increased in contralateral electrodes when the target followed in the same location as the threatening cues. This effect did not interact with evolutionary relevance. Both evolutionary relevant and evolutionary irrelevant threats led to increased P1 amplitude, although the effect was stronger for modern threats. We conclude that the threat-superiority effect is robust and largely independent of the type of threatening stimulus.     

Anomalous global effects induced by ‘blind’ distractors in visual hemifield defects

Previous research has revealed that a stimulus presented in the blind visual field of participants with visual hemifield defects can evoke oculomotor competition, in the absence of awareness. Here we studied three cases to determine whether a distractor in a blind hemifield would be capable of inducing a global effect, a shift of saccade endpoint when target and distractor are close to each other, in participants with lesions of the optic radiations or striate cortex. We found that blind field distractors significantly shifted saccadic endpoints in two of three participants with lesions of either the striate cortex or distal optic radiations. The direction of the effect was paradoxical, however, in that saccadic endpoints shifted away from blind field distractors, whereas endpoints shifted towards distractors in the visible hemifields, which is the normal global effect. These results provide further evidence that elements presented in the blind visual field can generate modulatory interactions in the oculomotor system, which may differ from interactions in normal vision.     

Refining the visual-cortical hypothesis in category learning

Participants produce steep typicality gradients and large prototype-enhancement effects in dot-distortion category tasks, showing that in these tasks to-be-categorized items are compared to a prototypical representation that is the central tendency of the participant’s exemplar experience. These prototype-abstraction processes have been ascribed to low-level mechanisms in primary visual cortex. Here we asked whether higher-level mechanisms in visual cortex can also sometimes support prototype abstraction. To do so, we compared dot-distortion performance when the stimuli were size constant (allowing some low-level repetition-familiarity to develop for similar shapes) or size variable (defeating repetition-familiarity effects). If prototype formation is only mediated by low-level mechanisms, stimulus-size variability should lessen prototype effects and flatten typicality gradients. Yet prototype effects and typicality gradients were the same under both conditions, whether participants learned the categories explicitly or implicitly and whether they received trial-by-trial reinforcement during transfer tests. These results broaden out the visual-cortical hypothesis because low-level visual areas, featuring retinotopic perceptual representations, would not support robust category learning or prototype-enhancement effects in an environment of pronounced variability in stimulus size. Therefore, higher-level cortical mechanisms evidently can also support prototype formation during categorization.