Impairment of the visuo-spatial sketch pad

A case study is presented of a female patient, ELD, who has difficulty in the immediate recall of short sequences of visuo-spatial material following a right-hemisphere aneurysm. Despite poor performance on tasks such as the Brooks Matrix and the Corsi Blocks, ELD is good at the immediate serial recall of letters even when presentation modality is visual and shows effects of phonological similarity and articulatory suppression. This pattern of performance represents a double dissociation from that which has been observed with the short-term memory patient PV (Vallar & Baddeley, 1984), who is extremely poor at serial recall of verbal material but shows no visual memory impairment. It is argued that ELD has an impairment to the visuo-spatial component of working memory (Baddeley, 1986) in the absence of any phonological loop deficit. Further investigation reveals that ELD performs poorly on mental rotation tasks and finds it difficult to use imagery mnemonics, but has no difficulty in retrieving visuo-spatial information from long-term memory so long as it was learnt before her illness.     

Persistent visual aura following catheter ablation in a patient with WPW syndrome

We report a patient who has had persistent visual disturbances since she underwent catheter ablation to treat her Wolff-Parkinson-White (WPW) syndrome. We examined her visual symptoms carefully and quantitatively by means of our newly developed method combining image-processing and psychophysics. We first simulated the patient's visual symptoms using image-processing techniques. Since the simulation indicated that she would be very sensitive to the edges of the visual stimuli, we evaluated her sensitivity to the edges using psychophysics. The results indicated that she was hypersensitive to the clear-cut edges of the visual stimuli. Her visual symptoms were very similar to those of visual aura of migraine, rather than those of photosensitive epilepsy. Magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT), electroenchepalogram (EEG), and visual-evoked potentials (VEP) in the patient were normal. No abnormalities in her fundus, visual field, or electroretinogram were found, either. Transesophageal echocardiography with bubble study indicated that she had a preexisting right-to-left shunt. We hypothesize that visual aura of migraine was triggered and made persistent by the catheter ablation in this patient. Although the relationship between migraine, catheter ablation, and right-to-left shunts is unknown, previous studies on the transcatheter closure of patent foramen ovale suggest a possible link between them. Catheter ablation in patients with migraine and preexisting shunts may lead to exacerbations in migraine symptoms.     

Boundary conditions for the modality effect: Type of material and time of test

Recall of auditory and visually presented information was studied using three different types of material. Although auditory presentation was superior for all three types of material, the size and pattern of the effect depended upon whether the visual presentation was successive or simultaneous. Successive visual presentation reduced recall performance compared to auditory presentation considerably for real sentences, while smaller effects were obtained for noun sequences and scrambled sentences. The overall supremacy in recall of auditory presented items was reduced further when compared to a simultaneous visual presentation. In the last two experiments, all effects of modality of presentation obtained in immediate recall were replicated, but were eliminated in delayed recall. The finding that this modality effect is eliminated in delayed recall is taken to indicate that semantic aspects of the material to be remembered are by and large unaffected by mode of presentation, while more superficial aspects are the ones influenced.     

Reading without phonology: Evidence from aphasia

This study of an aphasic dyslexic supports the view that there are separate visual and phonological pathways in reading. The patient retained a reading vocabulary of at least 16 500 words although she was unable to perform operations that critically depend on grapheme-to-phoneme conversion; these included reading nonsense words, recognizing rhymes and homophones, and accessing lexical entries from homophonic spellings such as “kote”. Typographical variation, such as mixed case presentation, did not interfere with her reading performance, which suggests that it is mediated by letter identification rather than by a wholistic method of word recognition. The total performance pattern strongly suggests that this patient identifies words by matching particular letter-strings with their corresponding meanings.     

Vision following extended congenital blindness

Animal studies suggest that early visual deprivation can cause permanent functional blindness. However, few human data on this issue exist. Given enough time for recovery, can a person gain visual skills after several years of congenital blindness? In India, we recently had an unusual opportunity to work with an individual whose case history sheds light on this question. S.R.D. was born blind, and remained so until age 12. She then underwent surgery for the removal of dense congenital cataracts. We evaluated her performance on an extensive battery of visual tasks 20 years after surgery. We found that although S.R.D.'s acuity is compromised, she is proficient on mid- and high-level visual tasks. These results suggest that the human brain retains an impressive capacity for visual learning well into late childhood. They have implications for current conceptions of cortical plasticity and provide an argument for treating congenital blindness even in older children.     

Visuo-spatial processing in working memory

This paper reports four experiments designed to develop a simple technique for the study of visuo-spatial processing within the working memory framework (Baddeley and Hitch, 1974). Experiment 1 involved the matching of successively presented random matrix patterns, as a secondary visual suppression task. This was coupled with rote rehearsal or a visual imagery mnemonic for learning lists of concrete words presented auditorily. Although memory performance with matching dropped overall, the visual mnemonic was differentially affected. Experiment 2 removed the matching decision, with visual presentation of unattended patterns. There was no overall effect of the unattended material, but use of the visual mnemonic was significantly affected. Experiment 3 replicated this result with simpler plain coloured squares as the unattended material.

In Experiment 4, for one group, the unattended material consisted of line drawings of common objects. For a second group, the lists of words for recall were presented visually, with or without unattended speech. The results suggested that unattended pictures disrupt use of a visual mnemonic, while unattended speech disrupts rote rehearsal.

These results suggest that unattended visual material has privileged access to the mechanism(s) involved in short-term visuo-spatial processing and storage. They also suggest that use of a concurrent visual matching task or of unattended visual material may provide tractable techniques for investigating this aspect of cognitive function within the context of working memory.     

Toddlers' traumatic memories

Three cases will be presented in which remote, accurate verbal and visual memories were present in, and from, toddlerhood for which the earliest age was 16 months. The age at which memories can be verbalized depends on the age of onset of speech phrases and cognitive ability. The memory may remain for over 30 years. Toddlers spontaneously report traumatic memories. The earlier the trauma occurs, the less the child is able to organize the material into a narrative form. The child is only able to relate the parts that are within his or her verbal repertoire and significant to him or her.     

Light and shadow in the life and work of Louise Nevelson

The life and work of the artist Louise Nevelson are examined through the lens of her ideas about light and shadow. Nevelson developed several ways of dealing with a basic fault established in childhood. Some ideas of Christopher Bollas are used in understanding the artist's relationships with art dealers who served her as transformational objects. The artist became the grandmother of environmental sculpture in America and saw her work as a bridge between the third and the fourth dimension--an idealized realm and a popular concept in twentieth-century art that she related directly to light and shadow. Colette Roberts, a dealer with whom she worked, allowed Nevelson to arrive at a signature style. Arne Glimcher, who represented her for twenty-four years, provided the material and psychological comfort that allowed Nevelson to explore new materials and new styles and to arrive at aesthetic solutions of remarkable power and sophistication through her eighty-ninth year. From the time she met Roberts in 1953 until the end of her life thirty-five years later, Nevelson's ideas about light and shadow expressed not only her thoughts about visual perception but her experience of her mother as her original transformational object and unthought known.     

One Good Turn Deserves Another

Elizabeth Bucar has provided a service to the guild with her introduction to the emergent field of visual ethics. In this comment I undertake to expand the picture she presents. I argue that the visual dimension of ethics includes a “dark side” not addressed in her piece, and go on to consider a number of current avenues of inquiry in which religious ethics intersects with visual studies. After briefly considering some of the distinctive methodological challenges attending the visual turn in ethics, I conclude my survey of this new field with some comments on the moral qualities of cinema.     

When visual and verbal memories compete: Evidence of cross-domain limits in working memory

Recently, investigators have suggested that visual working memory operates in a manner unaffected by the retention of verbal material. We question that conclusion on the basis of a simple dual-task experiment designed to rule out phonological memory and to identify a more central faculty as the source of a shared limitation. With a visual working memory task in which two arrays of color squares were to be compared, performance was unaffected by concurrent recitation of a two-digit list or a known seven-digit sequence. However, visual working memory performance decreased markedly when paired with a load of seven random digits. This was not a simple tradeoff, inasmuch as errors on the visual array and high digit load tasks tended to co-occur. Working memory for digits and visual information thus are both subject to at least one type of shared limit, not just domain-specific limitations. The nature of the shared limit is discussed.     

Cueing attention by relative motion in the periphery of the visual field

Sudden changes of visual stimulation attract attention. The observer's body motion generates retinal-flow field patterns containing information about his/her own speed and trajectory and relative motion of other objects. We investigated the effectiveness of relative motion as an attentional cue and compared it with conventional cueing by appearance of a frame in the far periphery of the visual field. In a group of ten subjects, contrast thresholds for the perception of static Gabor grating orientation [four alternative non-forced-choice (4ANFC)] task were determined at 20 degrees, 30 degrees, 40 degrees, and 60 degrees eccentricity. Subsequently, near-threshold discrimination performance of Gabor pattern orientation without versus with a ring-shaped cue was measured at the same positions. The same Gabor patterns were then presented embedded in a random-dot flow field, and uncued discrimination performance was compared with performance after presentation of a relative-motion cue (RMC), ie a small random-dot field with motion in the opposite direction of the flow field. Both the conventional ring cue and the RMC induced significantly increased discrimination performance at all test locations. With the parameters chosen for this study, the RMC was slightly less effective than the conventional cue, but its effects were somewhat more pronounced in the far periphery of the visual field. Thus, relative motion is a powerful cue to attract attention to peripheral visual objects and improves performance as effectively as a conventional ring cue. The findings have practical relevance for everyday life, in particular for tasks like driving and navigation.     

The imbalance of oculomotor capture in unilateral visual neglect

Visual neglect has been associated with an imbalance in the level of activity in the saccadic system: activity in the contralesional field is suppressed, which makes target selection unlikely. We recorded eye movements of a patient with hemispatial neglect and a group of healthy participants during an oculomotor distractor paradigm. Results showed that the interfering effects of a distractor were very strong when presented in her ipsilesional visual field. However, when the distractor was presented in her contralesional field, there were no interfering effects when the target was presented in her ipsilesional field. These findings could not be explained by the presence of a visual field defect as revealed by the results of two hemianopic patients. Our results are in line with an imbalance in the level of activity in the saccadic system in visual neglect because visual elements presented in the contralesional field did not compete for saccadic selection.     

Mirror reading of words and numbers: Practice and transfer effects

It remains unknown whether mirror reading represents a genuine text processing skill or is based on recognition of visual patterns. The present study attempts to determine whether (1) systematic practice with a particular mirrored typography also improves reading performance for other mirrored typographies, and whether (2) this transfer extends from lexical to numerical material and vice versa. The results show that short-term intensive practice with mirror-reversed words significantly improves reading performance not only for the trained typography but also for other mirrored typographies and mirror-reversed Arabic digits. Practice with mirror-reversed Arabic digits showed a mixed pattern of transfer effects with regard to other digit transformations and there were no transfer effects to lexical material. Hence, for lexical material, at least, improvement after training seems to be based on generalized skill with transfer effects beyond lexical material, rather than on mere improvement of visual recognition of the material used in training.     

Naïve realism: a simple approach

Naïve realism is often characterized, by its proponents and detractors alike, as the view that for a subject to undergo a perceptual experience is for her to stand in a simple two-place acquaintance relation toward an object. However, two of the leading defenders of naïve realism, John Campbell and Bill Brewer, have thought it necessary to complicate this picture, claiming that a third relatum is needed to account for various possible differences between distinct visual experiences of the same object (for example, differences that result from changes in the object’s spatial orientation relative to the subject, or from changes in the intensity with which the subject focuses her attention on the object). This, I argue, is a mistake. Once it is acknowledged that a subject’s visual experience acquaints her with more than just a single object, all of the relevant facts can be explained from within the simpler naïve realist framework.

     

The memory of two great mental calculators: Charcot and Binet's neglected 1893 experiments

French neurologist Jean Martin Charcot (1825-1893) and French psychologist Alfred Binet (1857-1911) are almost unknown as investigators who conducted original and fascinating studies in the area of memory. In a series of 1893 experiments, they compared the performance of two expert mental calculators, Jacques Inaudi and Périclès Diamandi, in tasks that consisted of recalling digits. Inspired by Ribot's psychological work (1881), they believed in the existence of not one type of memory but several partial, special, and local memories, each devoted to a particular domain. In all arithmetical prodigies, memory for digits is abnormally developed compared with other memories. Inaudi was considered to be an auditory memory-based mental calculator; when memorizing digits, he did not rely onthe appearance of the items or create visual imagery of any kind. Rather, he remembered digits principally by their sounds. Inaudi's methods of calculation and memorization were original and different from those used by Diamandi, who was a typical visual memory-based mental calculator. The experiments presented in the 1893 article were among the first scientific demonstrations of the importance to psychology of studying different types of memory. The present work gives a translation of this pioneering experimental article on expert calculators by Charcot and Binet, instructive for the comprehension of normal memory.     

"The W and M are mixing me up": use of a visual code in verbal short-term memory tasks

When normal participants are presented with written verbal short-term memory tasks (e.g., remembering a set of letters for immediate spoken recall) there is evidence to suggest that the information is re-coded into phonological form. This paper presents a single case study of MJK whose reading follows the pattern of phonological dyslexia. In short-term memory tasks MJK does not phonologically re-code written materials but, it is argued, uses a visual code. There are three main lines of evidence for this, (a) MJK tends to substitute visually similar items for one another, (b) her performance is better with visual than auditory stimuli, and (c) she is able to remember numbers (e.g., 8) better than written words (e.g., eight). Investigation of short-term memory in others with phonological dyslexia is warranted.     

From "logographic" to normal reading: the case of a deaf beginning reader

Visual word recognition of a profoundly deaf girl (AH) with developmental reading disorders was explored using an experimental technique that measures performance as a function of eye fixation within a word. AH's fixation-dependent word recognition profile revealed that she was inferring the identity of words using a "logographic" reading strategy (i. e., using salient visual features). Following this observation a special training program that enhances the understanding of grapheme-phoneme relations was applied. After few months of training, AH's reading skills improved, while her fixation-dependent performance changed to become like that of normal readers. We discuss the impact of our technique for the early diagnosis of reading impairments.     

Anticipation and variation in visual content

This article is composed of three parts. In the first part of the article I take up a question raised by Susanna Siegel (Philosophical Review 115: 355–388, 2006a). Siegel has argued that subjects have the following anticipation: (PC) If S substantially changes her perspective on o, her visual phenomenology will change as a result of this change. She has left it an open question as to whether subjects anticipate a specific kind of change. I take up this question and answer it in the affirmative. By appealing to a widely held view of perceptual content, the view that we represent ‘factual’ properties in perception, I argue that (PC) can be refined as follows: (PC’) If S substantially changes her perspective on o, her visual phenomenology will present different views of o’s factual properties. In the second part of the article I argue that (PC’) implies that there are cases in which normal perceivers have different perceptual content under identical viewing conditions. The differences in perceptual content are due to differences in the determinacy of visual anticipation. I draw the conclusion that perceptual content is rich in the sense that it includes a unique contribution from individual perceivers. In the final part of the article, I discuss some open issues regarding the way in which (PC’) relates to the personal/sub-personal distinction, empirical models, and the distinction between perception and cognition.     

Assessing tactile perception: effects of different visual barriers on performance

Blindfolding candidates when testing their tactile performance may increase their anxiety. This study examined whether different visual barriers would influence tactile performance on timed tasks. It was hypothesised that candidates using a blindfold would be more anxious, but that they would benefit by the potentially positive effects of arousal on performance and not differ from candidates using a screen to limit visual access to task material. 200 participants (ages 19 to 30 years), randomly assigned to the two conditions, completed a tactile perception task, as well as an anxiety scale. In contrast to the expected outcome, the screen sample took significantly longer to complete the task. This was hypothesised to be the result of increased distraction given competing cross-modal attentional demands and the consequent visual and tactile attention switching. Practitioners may need to consider the influences of visual interference when assessing tactile performance.