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R Latto

Publications and source records attributed to R Latto.

12 recordsLinked to original sources
PubMed2000

An oblique effect in aesthetics: homage to Mondrian (1872-1944).

The effect of the orientation of Mondrian's paintings on their aesthetic appeal was examined. Eight paintings, four with horizontal/vertical frames in the original and four with oblique frames, were presented in eight different orientations and rated for aesthetic appeal on a 7-point scale. There was a stronger preference for pictures presented so that their component lines were horizontal and vertical than for pictures presented with their component lines in an oblique orientation. In addition, subjects showed a preference for the original orientation, perhaps because rotation changes the lateral balance of the paintings as well as the orientation of the component lines. There was no overall preference for one frame orientation over another, but there was an interaction between frame orientation and component orientation, resulting in a preference for paintings where the components were parallel to the surrounding frame. It is suggested that the aesthetic oblique effect reported here is related to the oblique effect in orientation perception and the privileged access which horizontal and vertical lines have to the visual system. This offers a possible mechanism for aesthetic judgments of abstract patterns: we find pleasing those stimuli which are closely tuned to the properties of the human visual system.

Adult↗
PubMed1996

The role of inferior parietal cortex and fornix in route following and topographic orientation in cynomolgus monkeys.

The effects of inferior parietal cortex lesions (Area 7a/PG) and bilateral transection of the fornix were compared within a single species (cynomolgus monkeys) and using a single paradigm of route running in a traditional (fixed entry and exit) whole-body maze. Experiment 1 showed that Area 7a/PG but not fornix lesions impaired post-operative retention of route running. Experiment 2 assessed the contribution of visual cues and proprioceptive/kinaesthetic guidance to route running and showed that in non-lesioned monkeys route running was influenced to varying degrees by proprioceptive guidance, visual extra-maze room cues and visual maze stimuli. Post-operative assessment of maze performance, including error patterns, retraining and misreaching (Experiment 1), suggested that monkeys in the Parietal Group were not topographically disoriented and did not have a spatial long-term memory deficit, but it was their difficulty responding to local spatial cues which initially impaired route running. Investigation of cue use (Experiment 2) also showed the sensitivity of the Parietal Group to local spatial cues; they were significantly impaired on entry through a new start position when the relationship between maze stimuli and extra-maze cues was changed. The Fornix Group showed no retrograde long-term memory deficit for route-running (Experiment 1). However, in Experiment 2, where a new goal position was learnt, the Fornix Group did show an anterograde memory deficit.

Animals↗
PubMed1986

Impairments in route negotiation through a maze after dorsolateral frontal, inferior parietal or premotor lesions in cynomolgus monkeys.

Ten cynomolgus monkeys were trained to follow a fixed route through a whole-body maze consisting of 3 X 3 matrix of 9 compartments, all with interconnecting doors. Two monkeys learned to use proprioceptive guidance such that they tended to produce the same sequence of movements even if they entered the maze by a different door. They were not impaired by bilateral lesions to inferior parietal cortex (Area 7a/PG). The rest used non-proprioceptive guidance relying on external cues in the environment, probably outside the maze. These were impaired by bilateral lesions of either dorsolateral frontal or posterior parietal cortex. At least 3 different strategies may be used for route negotiation. Postoperative comparisons of the frontal and parietal groups on the effects of rearranging the external cues and on learning a new route through the maze suggested that the groups were differentially impaired in the use of different strategies. In a subsequent study, bilateral lesions to premotor cortex (Area 6) resulted in an impaired ability to follow a route using either proprioceptive or external cues.

Animals↗
PubMed1986

The role of inferior parietal cortex and the frontal eye-fields in visuospatial discriminations in the macaque monkey.

Macaque monkeys with bilateral lesions of either the frontal eye-fields (Area 8) or the inferior parietal lobule (Area 7a or PG) were compared with unoperated controls on their ability to perform a series of 8 pre-operatively learnt visual discriminations. Simple non-spatial discriminations were not affected, but the frontal group was affected when the stimuli in a shape discrimination varied in position from trial to trial and the parietal group was impaired on the judgement of centre. Both groups were impaired on a spatial landmark test which used luminous stimuli presented in the dark, in positions that varied randomly with respect to the monkey so that only allocentric cues were available. Postoperative trial-by-trial error analysis on the landmark test showed that, whereas spatial discriminability was a factor in determining the performance of the experimental groups, degree of cue-response separation and response perseveration were not. A comparison of the performance of the two groups on all 8 tests suggests that although both are impaired on spatial discriminations, the frontal eye-fields are concerned with spatially organising responses to explore the environment, while the inferior parietal lobule is concerned more directly with the processing of spatial information and the perception of spatial relationships.

Animals↗
PubMed1985

Apperceptive agnosia due to carbon monoxide poisoning. An interpretation based on critical band masking from disseminated lesions.

Apperceptive visual agnosia is normally held to be a specific deficit in 'apperception' - a hypothetical postsensory stage in visual processing. This paper describes the investigation of a patient diagnosed as suffering from a classical apperceptive agnosia resulting from carbon monoxide poisoning. Controlled behavioural testing confirmed the apparent agnosia but revealed that he could be trained to make a number of visual discriminations which had not been apparent from routine clinical examination and that he suffered a number of subtle sensory impairments which likewise had not hitherto been apparent. Evoked potential recording to grating patterns showed a complex pattern of brain responses involving interactions between spatial frequency, orientation and hemisphere recorded from. The data suggested that the agnosia was caused by sensory impairments rather than a deficit in apperception. We proposed that the impairments were caused by loss of certain spatial frequency and orientation information but rejected an interpretation based on the concept of processing channels in favour of one based on object contour masking by a peppery field defect caused by disseminated lesions. This interpretation received some support from fine grain static perimetry, contrast sensitivity function measurement and orientation discrimination in the two hemifields. Qualitatively similar results were obtained in normal subjects whose field was artificially masked. The results have implications for theories of visual agnosia and for theories of vision based on the concept of processing channels.

Agnosia↗
PubMed1982

The role of frontal eye-fields and superior colliculi in visual search and non-visual search in rhesus monkeys.

Rhesus monkeys were tested on a visual search task in which they had to find and retrieve a peanut from a display of visually similar but inedible objects. The speed with which they did so was measured. Animals in which the superior colliculi or frontal eye-fields had been removed took longer to find the peanut than two operated control groups. Animals with collicular lesions had longer latencies than those with frontal eye-fields removed. These two groups were also tested on a second task, non-visual search, in which a peanut was concealed in each of 25 identical holes. The animals' task was to retrieve all 25 peanuts as quickly as possible. The group with frontal eye-fields removed made significantly more return errors, i.e. returning to a hole already sampled, than the control group but, in contrast to the first task, the animals with collicular lesions were not impaired. The results are related to the physiological properties of frontal eye-fields and superior colliculi and to the effects of frontal cortical brain damage in man. It is suggested that the frontal eye-fields are concerned with internally organized, i.e. voluntary, eye scanning whereas the superior colliculi are concerned with the detection and location of targets which are then fixated involuntarily.

Animals↗
PubMed1978

The effects of bilateral frontal eye-field, posterior parietal or superior collicular lesions on visual search in the rhesus monkeys.

Superior collicular, frontal eye-field and posterior parietal lesions increased the time taken to find a circular target among other geometrical shapes. The collicular monkeys were considerably more impaired than the other groups, suggesting that the superior colliculus is the main neural structure underlying this highly practised visual search task. Failure to respond in the 5 sec allowed on each trail increased for all groups, and the collicular and frontal groups showed a small increase in false positive errors. None of the groups increased search time for a near-threshold target on a homogenous background. [corrected] Analysis of the latencies of individual trials suggest that scanpaths over the display were still systematic after the lesions. This suggests that the search was being slowed down either by the need to make more correction saccades to give accurate fixations of the stimuli being discriminated, or by an increase in latencies specificially for those saccades that shift the gaze between stimuli.

Animals↗