Nonsense Shapes Research Articles

EFFECT OF EVALUATIVE CONDITIONING ON AFFECTIVELY NEUTRAL NONSENSE SHAPES

The present study examined the effect of evaluative conditioning on affectively neutral novel contour shapes. In the experiment, two nonsense shapes were paired with positive and negative personality traits, and were presented to participants (N = 26). These shapes and positive or negative nouns were then used as primes and targets for the affective priming procedure at stimulus onset asynchrony (SOA) 300 and 1000. Results showed that, at both SOAs, positive target words presented immediately after the shape paired with positive traits and negative target words presented immediately after the shape paired with negative traits caused faster evaluation than the other combinations. These results suggest that both automatic evaluation and intentional expectation are linked with evaluative conditioning.

Can One Suppress Subliminal Words?

Subliminal words cause behavioral priming, yet the depth of their processing remains debated. Using transcranial magnetic stimulation (TMS), Nakamura et al. demonstrate in this issue of Neuron that this subliminal priming effect can be selectively disrupted. Distinct TMS sites disrupt priming in lexical decision and pronunciation tasks, suggesting that task set influences subliminal processing.

The ties that keep us bound: Top-down influences on the persistence of shape-from-motion

The phenomenon of perceptual persistence after the motion stops in shape-from-motion displays (SFM) was used to study the influence of prior knowledge on the maintenance of a percept in awareness. In SFM displays an object composed of discontinuous line segments are embedded in a background of randomly oriented lines. The object only becomes perceptible when the line segments that compose the object and the lines that compose the background move in counterphase. Critically, once the movement of the line segments stops, the percept of the object persists for a short period of time. In the present study, perceptual persistence for digits exceeded that reported for nonsense shapes composed of the same line segments. This result is taken as evidence that the processes involved in the persistence of SFM, and therefore sustained perception, are sensitive to top-down influences.

Brain Networks Associated with Cognitive Reserve in Healthy Young and Old Adults

In order to understand the brain networks that mediate cognitive reserve, we explored the relationship between subjects' network expression during the performance of a memory test and an index of cognitive reserve. Using H2(15)O positron emission tomography, we imaged 17 healthy older subjects and 20 young adults while they performed a serial recognition memory task for nonsense shapes under two conditions: low demand, with a unique shape presented in each study trial; and titrated demand, with a study list size adjusted so that each subject recognized shapes at 75% accuracy. A factor score that summarized years of education, and scores on the NART and the WAIS-R Vocabulary subtest was used as an index of cognitive reserve. The scaled subprofile model was used to identify a set of functionally connected regions (or topography) that changed in expression across the two task conditions and was differentially expressed by the young and elderly subjects. The regions most active in this topography consisted of right hippocampus, posterior insula, thalamus, and right and left operculum; we found concomitant deactivation in right lingual gyrus, inferior parietal lobe and association cortex, left posterior cingulate, and right and left calcarine cortex. Young subjects with higher cognitive reserve showed increased expression of the topography across the two task conditions. Because this topography, which is responsive to increased task demands, was differentially expressed as a function of reserve level, it may represent a neural manifestation of innate or acquired reserve. In contrast, older subjects with higher cognitive reserve showed decreased expression of the topography across tasks. This suggests some functional reorganization of the network used by the young subjects. Thus, for the old subjects this topography may represent an altered, compensatory network that is used to maintain function in the face of age-related physiological changes.

Neglect Dyslexia With a Stimulus-Centred Deficit and Without Visuospatial Neglect

This paper reports a single case of ipsilesional left neglect dyslexia and interprets it according to the three-level model of visual word recognition proposed by Caramazza and Hillis (1990). The three levels reflect a progression from the physical stimulus to an abstract representation of a word. RR was not impaired at the first, retinocentric, level, which represents the individual features of letters within a word according to the location of the word in the visual field: She made the same number of errors to words presented in her left visual field as in her right visual field. A deficit at this level should also mean the patient neglects all stimuli. This did not occur with RR: She did not neglect when naming the items in rows of objects and rows of geometric symbols. In addition, although she displayed significant neglect dyslexia when making visual matching judgements on pairs of words and nonwords, she did not do so to pairs of nonsense letter shapes, shapes which display the same level of visual complexity as letters in words. RR was not impaired at the third, graphemic, level, which represents the ordinal positions of letters within a word: She continued to neglect the leftmost (spatial) letter of words presented in mirror-reversed orientation and she did not neglect in oral spelling. By elimination, these results suggest RR's deficit affects a spatial reference frame where the representational space is bounded by the stimulus: A stimulus-centred level of representation. We define five characteristics of a stimulus-centred deficit, as manifest in RR. First, it is not the case that neglect dyslexia occurs because the remaining letters in a string attract or capture attention away from the leftmost letter(s). Second, the deficit is continuous across the letter string. Third, perceptually significant features, such as spaces, define potential words. Fourth, the whole, rather than part, of a letter is neglected. Fifth, category information is preserved. It is concluded that the Caramazza-Hillis model accounts well for RR's data, although we conclude that neglect dyslexia can be present when a more general visuospatial neglect is absent.

The Representation of Shape in the Context of Visual Object Categorization Tasks

To investigate the role of human fusiform gyrus in shape processing, we determined the effect of shape degradation on BOLD contrast in this region with fMRI during three tasks requiring subjects to determine either whether two successively presented nonsense shapes had the same global orientation (OR task); whether two successively presented meaningful objects belonged to the same basic level category (CAT task); or whether two successively presented objects represented the same exemplar of a category (EX task). On the behavioral level, shape degradation by locally shifting the pixels constituting the lines of stimuli had no effect on performance in the OR task, while it was detrimental to performance in the CAT and EX tasks. In comparison to the OR task, both the CAT and EX tasks were associated with activations in the occipitotemporal and parietal cortex. When shape degradation was applied, activation in the middle fusiform gyrus was reduced in all tasks. The occurrence of this effect in the OR task indicates that it is independent of memory representations. The persistence of the effect in both tasks that showed a behavioral effect of degradation suggests that it does not reflect the amount of shape processing performed on the stimuli, but rather the specificity of the final perceptual representation that can be built from the shape information that is available. Other studies have shown effects of stimulus familiarity and task requirements in the fusiform gyrus, suggesting that there is no need to assume different modules for perceptual representation and representation in memory.

Somatoperceptual Asymmetry for Cognitive Stimuli: Support from Experimental and Clinical Observations

Two studies, one experimental with intact-brain subjects (Study I), and one clinical with left or right hemisphere-damaged and non-neurological general medical patients (Study II), were conducted to examine somatolateral asymmetry in the recognition of verbal (letter) and visuospatial (nonsense shapes) stimuli. Blindfolded subjects were required to explore two stimuli dichhaptically, and were instructed to haptically identify the target stimulus in a set of test stimuli. The findings of Study I indicated that fewer trials were required to recognise nonsense shapes when they were presented to the left hand, whereas fewer trials were required for letters when they were presented to the right hand. The findings of Study II indicated that performance of the hand ipsilateral to the damaged left hemisphere was better for nonsense shapes than for letters, and performance of the hand ipsilateral to the damaged right hemisphere was better for letters than for nonsense shapes.

Somatoperceptual Asymmetry for Cognitive Stimuli: Support from Experimental and Clinical Observations

Two studies, one experimental with intact-brain subjects (Study I), and one clinical with left or right hemisphere-damaged and non-neurological general medical patients (Study II), were conducted to examine somatolateral asymmetry in the recognition of verbal (letter) and visuospatial (nonsense shapes) stimuli. Blindfolded subjects were required to explore two stimuli dichhaptically, and were instructed to haptically identify the target stimulus in a set of test stimuli. The findings of Study I indicated that fewer trials were required to recognise nonsense shapes when they were presented to the left hand, whereas fewer trials were required for letters when they were presented to the right hand. The findings of Study II indicated that performance of the hand ipsilateral to the damaged left hemisphere was better for nonsense shapes than for letters, and performance of the hand ipsilateral to the damaged right hemisphere was better for letters than for nonsense shapes.

Tactile morphagnosia secondary to spatial deficits

A 73-year old man showed visual and tactile agnosia following bilateral haemorrhagic stroke. Tactile agnosia was present in both hands, as shown by his impaired recognition of objects, geometrical shapes, letters and nonsense shapes. Basic somatosensory functions and the appreciation of substance qualities (hylognosis) were preserved. The patient’s inability to identify the stimulus shape (morphagnosia) was associated with a striking impairment in detecting the orientation of a line or a rod in two- and three-dimensional space. This spatial deficit was thought to underlie morphagnosia, since in the tactile modality form recognition is built upon the integration of the successive changes of orientation in space made by the hand as it explores the stimulus. Indirect support for this hypothesis was provided by the location of the lesions, which could not account for the severe impairment of both hands. Only those located in the right hemisphere encroached upon the posterior parietal cortex, which is the region assumed to be specialised in shape recognition. The left hemisphere damage spared the corresponding area and could not, therefore, be held responsible for the right hand tactile agnosia. We submit that tactile agnosia can result from the disruption of two discrete mechanisms and has different features. It may arise from a parietal lesion damaging the high level processing of somatosensory information that culminates in the structured description of the object. In this case, tactile recognition is impaired in the hand contralateral to the side of the lesion. Alternatively, it may be caused by a profound derangement of spatial skills, particularly those involved in detecting the orientation in space of lines, segments and complex patterns. This deficit results in morphagnosia, which affects both hands to the same degree.

The continuous performance test, identical pairs version (CPT-IP) : III: Brain functioning during performance of numbers and shapes subtasks

The numbers and shapes subtasks of the CPT-1P are difficulty-matched measures of independent aspects of attentional skill that have been used to differentiate the impairments of schizophrenics and major depressives. Previous studies suggest that they tap into lateralized aspects of attentional performance. To investigate this hypothesis, seven subjects free of psychiatric illness were presented with these CPT-IP subtasks during a SPECT procedure. Subtasks — 4-digit number strings and nonsense shapes — were administered on successive weeks, in counterbalanced order, simultaneous with administration of 10 mCi 99mTc HMPAO. Scanning took place after 10 min of test performance. Quantitative data were extracted from each scan via a semi-automated region of interest (ROI) analysis which defined eight cortical and four subcortical ROI on each of five transverse slices. Data for each ROI were normalized and compared between task conditions. Results indicate that the two tasks produce different patterns of functioning within two general areas of the brain. First, during Numbers task performance, left-sided activity was increased on multiple transverse slices in an anterior subcortical region that incorporated the anterior cingulate, frontal white matter, and much of the basal ganglia. Left-sided activity was also increased in a posterior subcortical region including the left side of the thalamus. Lateralization of function, defined as relative activity on the left and right sides, changed within these regions across tasks, but primarily as a result of the contribution of increased or decreased activity on the left side alone. Second, relative perfusion to occipital regions, bilaterally, was more extensive during the Shapes task. These results suggest that subtle alterations in stimulus parameters can affect activation patterns in regions that are critically associated with task performance. They also suggest that the Numbers task may provide more robust activation of anterior attention systems, that may better discriminate the functioning of these systems in normal and psychopathological groups.

The neural regions sustaining object recognition and naming.

This positron emission tomography study dissociates the neural correlates of object recognition and naming. Stimuli comprised coloured outline drawings of objects and coloured nonsense shapes. Subjects either viewed or explicitly named objects, similarly they viewed or named the colour of the shapes. Activations common to object and colour naming were identified by contrasting the explicit naming conditions (objects and colours) with the control (viewing) conditions. Activations associated with object recognition were identified by contrasting both object conditions (naming and viewing) with both shape conditions and activations specific to object or colour naming were identified by contrasting object naming (relative to object viewing) with colour naming (relative to shape viewing). The results associate: (i) object recognition with left middle occipital and bilateral anterior temporal cortices; (ii) modality independent naming with left posterior basal temporal lobe and the left prefrontal cortex; (iii) areas specific to object naming with left temporal extrasylvian regions, left anterior insula and right cerebellum; and (iv) areas specific to colour naming with left posterior lingual and fusiform gyri and midline cerebellum. These results are discussed in relation to previous neuroimaging and neuropsychological findings.

Neural systems for tactual memories

1. The aim of this study was to investigate the neural systems involved in the memory processing of experiences through touch. 2. Regional cerebral blood flow was measured with positron emission tomography by means of the water bolus H2(15)O methodology in human subjects as they performed tasks involving different levels of tactual memory. In one of the experimental tasks, the subjects had to palpate nonsense shapes to match each one to a previously learned set, thus requiring constant reference to long-term memory. The other experimental task involved judgements of the recent recurrence of shapes during the scanning period. A set of three control tasks was used to control for the type of exploratory movements and sensory processing inherent in the two experimental tasks. 3. Comparisons of the distribution of activity between the experimental and the control tasks were carried out by means of the subtraction method. In relation to the control conditions, the two experimental tasks requiring memory resulted in significant changes within the posteroventral insula and the central opercular region. In addition, the task requiring recall from long-term memory yielded changes in the perirhinal cortex. 4. The above findings demonstrated that a ventrally directed parietoinsular pathway, leading to the posteroventral insula and the perirhinal cortex, constitutes a system by which long-lasting representations of tactual experiences are formed. It is proposed that the posteroventral insula is involved in tactual feature analysis, by analogy with the similar role of the inferotemporal cortex in vision, whereas the perirhinal cortex is further involved in the integration of these features into long-lasting representations of somatosensory experiences.

Distortion of size perception in visuospatial neglect.

A number of studies have shown that most patients with symptoms of unilateral (left-sided) visuospatial neglect make consistently rightward errors when attempting to bisect a horizontal line at its midpoint. One possible interpretation of this impairment is that such patients misperceive the left half of the line: that is, that they underestimate its extent relative to the right half. We have carried out direct tests for such a perceptual distortion in three neglect patients by asking them to make matching judgements on pairs of horizontal rectangles, vertical rectangles or nonsense shapes, of varying relative size, presented on a computer screen. We report here that all of the patients tested showed a significant and substantial relative underestimation of the horizontal extent or area of stimuli presented on the left side of their egocentric space. There was no such misperception of vertical extent. It is suggested that size perception may be partially determined by a representational system that is anatomically centred in the parieto-temporal region of the brain. The results are interpreted in terms of damage to this system in neglect patients.

Hemispheric Differences in Image Generation and Use in the Haptic Modality

Forty adults and 40 children, all right-handed, were presented with either of two series of six nonsense shapes to palpate: Those who were divided into sections by grid lines and thus provided categorical information or those who provided a whole shape and coordinate information that could be processed globally. Subjects were given an Input condition where they formed a mental representation of the shape while palpating the unseen tactual stimulus with either hand, followed by an Evaluation condition in which they attempted to solve the task by generating and using the previously stored image. Evaluation response times showed that the left hemisphere was significantly faster at generating images from categorically stored information. Neither hemisphere had an advantage when generating an image from globally stored information.

Visual-spatial learning in nonalcoholic young adults with and those without a family history of alcoholism.

Visual-spatial learning in young adult nonalcoholic men and women with (FH+) and those without (FH-) a family history of alcoholism was investigated using nonsense shapes of high and low verbal association value. Four groups of FH+ and FH- men and women, 16 subjects in each group, were tested. The male FH+ group required significantly more trials to reach learning criterion and made more errors than the male FH- group; the FH effect was not significant in females although similar trends were present. Women exhibited significantly poorer visual-spatial learning compared to the men. High compared to low verbal association shapes were learned in fewer trials with fewer errors by all groups. There were no significant FH by verbal association interactions, indicating that the impaired visual-spatial learning in the FH+ men could not be ascribed to the meaningfulness dimension of the nonsense shapes. These results suggest that the impaired visual-spatial learning found in adult children of alcoholics (ACOAs) might be due in part to premorbid cognitive deficits.

Lateralization in haptic processing: An apparatus for analyzing manual strategies

We describe an apparatus for testing laterality in haptic processing in the discrimination of nonsense shapes in humans or monkeys. The system, which permits either mono- or dichhaptic discrimination, automatically provides data on the measurement of accuracy along with information on hand exploratory strategies.

Can Visual Neglect Operate in Object-centred Co-ordinates? An Affirmative Single-case Study

Abstract Clinical evidence from visuospatial neglect suggests that some patients neglect one side of each individual object in a scene, rather than just one side of the scene as a whole. For example, in copying they may produce only the right side of objects from both the right and left of the original drawing. One interpretation of this phenomenon is that neglect may operate in object-centred co-ordinates. We examined this hypothesis in a right-hemisphere damaged patient, PP, who shows severe and intractable left neglect. Her task was to judge whether two elongated nonsense shapes, presented one above the other, were the same or different. When the principal axis of each shape was vertical PP missed differences on the left. When the shapes were both rotated 45° clockwise or anticlockwise, she continued to neglect differences on the left of the objects' axes, even when these differences fell on the right of the sagittal midline. This demonstrates that neglect can be object-centred in the sense of operatin...

A New Test of Object Decision: 2D Silhouettes Featuring a Minimal View

A new test of object decision in which a minimal view 2D silhouette of an object is presented together with 3 nonsense shapes has been administered to a consecutive series of patients with right and left hemisphere lesions. There was a significant deficit in the right hemisphere lesion group as compared with the left hemisphere group. It is concluded that this object decision test provides a measure of the integrity of pre-semantic perceptual processing systems.

Event and Decay of the Aesthetic Experience

The theory of eventualism states that the specific aim of art is the aesthetic event. The aesthetic event is operatively defined as the sum of all different interpretations which the same stimulus can evoke from a group of people, The theory also states that after long-term exposure, the stimulus will become familiar and the scattering of the interpretations will decay into a few conformist possibilities. When an aesthetic stimulus is completely decayed it becomes an ordinary object. A study was conducted comparing eventualist and preference responses to a set of eighteen nonsense shapes of three different degrees of complexity. Short-term and long-term responses were also compared. The results suggest that eventualist and preference responses are positively intercorrelated in the short term and strongly positively intercorrelated in the long term. Very important cases of divergency are discussed. More complex stimuli received higher eventualist scores and decayed more slowly than the less complex ones. The more complex stimuli also scored better results in the scale of preferences, and here the differences were even more significant.

Perceptual Asymmetries in the Somatosensory System: A Dichhaptic Experiment and Critical Review of the Literature from 1929 to 1986

Dichhaptic matching of 3-D nonsense shapes was used to assess sex-specific differences in haptics. In an initial object exploration/description phase, strategy was manipulated with instructions to encode each object using either a visual image (which was drawn) or verbal description (tape recorded). These drawings or tape recordings were subsequently used on their own to identify each object. Attempts were made to maintain similarity between the verbal and spatial procedures, to avoid methodological biasing of hand superiorities (e.g., the same number of alternatives and the same presentation times were used). Differences in hand superiority did not, however, result. To obtain a broader perspective, a critical review table was compiled of the entire somatosensory asymmetry literature. Clear patterns emerged for all types of task when results potentially stemming from methodological biases and those based on only certain levels of samples were excluded. Somatosensory perceptual asymmetries are not robust, although hand superiorities are in the predicted direction when they do occur; nevertheless, we find little support for sex-specific asymmetries in these studies. Dichhaptic presentations lack the efficacy of other somatosensory (as well as tachistoscopic) tasks overall, possibly because of the time scale necessary for free haptic exploration.