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Biomedical subjects

G Underwood

Publications and source records attributed to G Underwood.

At least 19 recordsLinked to original sources
PubMed1999

Driving experience and the functional field of view.

Research has suggested that novice drivers have different search strategies compared with their more experienced counterparts, and that this may contribute to their increased accident liability. One issue of concern is whether experienced drivers have a wider field of peripheral vision than less experienced drivers. This study attempted to distinguish between people of varying driving experience on the basis of their functional fields of view. Participants searched video clips taken from a moving driver's perspective for potential hazards while responding to peripheral target lights. Hit rates for peripheral targets decreased for all participant groups as processing demands increased (i.e. when hazards occurred) and as the eccentricity of the target increased, though there was no interaction. An effect of experience was also found which suggests that this paradigm measures a perceptual skill or strategy that develops with driving experience.

Accidents, Traffic↗
PubMed1998

Visual search of driving situations: danger and experience.

Previous research on visual search in driving suffers from a number of problems: small sample sizes, a concentration on mundane situations, and a failure to link results to more general psychological theory. The study reported in this paper addresses these issues by recording the eye movements of a large sample of drivers while they watched films of dangerous driving situations and comparing the findings with those from more general studies on scene perception. Stimuli were classified according to the types of road shown and the degree of danger present in the scenes. Two groups of subjects took part, fifty-one young novice drivers who had just gained a full driving licence and twenty-six older more experienced drivers. Dangerous situations were characterised by a narrowing of visual search, shown by an increase in fixation durations, a decrease in saccade angular distances, and a reduction in the variance of fixation locations. These effects are similar to the concept of 'attention focusing' in traumatic situations as it is described in the literature on eyewitness memory. When road types are compared, the least visually complex rural roads attracted the longest fixation durations and the shortest angular saccade distances, while the most visually complex urban roads attracted the greatest spread of search but the shortest fixation durations. Differences between the groups of subjects were also present. Novices had longer fixation durations than experienced drivers, particularly in dangerous situations. Experienced drivers also fixated lower down and had less vertical variance in fixation locations than novices.

Adolescent↗
PubMed1997

Eye fixations, speech rate and bilingual digit span: numeral reading indexes fluency not word length.

The present study examined whether the reading of language-neutral stimuli, as numerals are, at maximal speed by bilinguals indexes processes related to fluency rather than differences in articulation time between languages. We tested two groups of bilinguals that spoke the same languages (Finnish and Swedish) but whose mother tongues were different and obtained measures of Arabic numeral processing by monitoring eye movements. These measures were contrasted with articulation and numeral reading estimates of word length. The results indicated that Finnish- and Swedish-dominant bilinguals had shorter gaze durations and shorter reading times in their respective dominant languages, whereas both groups articulated digits faster in Swedish than Finnish. The Swedish-dominant group had a larger digit span in Swedish, whereas digit span was marginally greater in Finnish than Swedish for the Finnish-dominant group. The finding that numeral reading was influenced by cognitive loads independent of articulation, thus, moderated the view that bilingual digit span effects are mediated exclusively by variation in word length between languages.

Finland↗
PubMed1997

Studying expertise in music reading: use of a pattern-matching paradigm.

Two experiments are described that make use of a pattern-matching paradigm to investigate perceptual processing of music notation. In Experiment 1, it is reported that the speed of comparing two visually presented musical sequences is related to the sight-reading skill of the subjects. The effect of the temporal and pitch structure of the comparison stimuli is also assessed. In Experiment 2, eye-movement recordings were taken as subjects performed the task. These data demonstrated that more experienced musicians are able to perform the comparisons with fever, and shorter, glances between the patterns. These and other findings suggest that skilled sight-reading is associated with an ability to rapidly perceive notes or groups of notes in the score, and confirm that the pattern-matching paradigm is a useful tool in examining expertise in music reading.

Adolescent↗
PubMed1995

Inspecting asymmetric presentations of words differing in informational and morphemic structure.

Are laterality effects in visual word recognition a product of functional asymmetry of the cerebral hemispheres or a result of stimulus inspection factors such as asymmetric eye fixations before and during visual presentation, different movement time to asymmetric targets, an interaction of the informative components, or morphemic structure of a target with a drop in acuity with distance? Two experiments were conducted to address these questions. Experiment One recorded the inspection of prefixed and matched control words presented unilaterally for 200 msec. Experiment Two displayed suffixed words and their appropriate controls. The words also varied in their information distribution. Reader's eye movements were monitored while they inspected the target words in preparation for a synonym judgement task. Measures of the location of the initial fixation on the screen showed that subjects were not biased to the right visual field prior to stimulus onset. When only those occasions in which the subject had correctly fixated the central cursor were analyzed, a robust right visual field advantage was observed on many of the target inspection time measures, but no reliable difference was observed for faster movement time to the right visual field's target compared to that observed in the left visual field. Neither the distribution of information within the word nor its morphemic structure affected the pattern of any inspection time measures. Consequently, such factors can be ruled out as threats to the hypothesis concerned with the functional asymmetry of the cerebral hemispheres.

Acoustic Stimulation↗
PubMed1993

Modelling of safety measure effects and risk compensation.

A model is proposed for the description of effects of safety measures introduced into a road transport system. The model explains the motives of road users' risk compensation towards the measures, and indicates when behavioural adaptation is likely to take place and its effects on road safety programmes. At its core the model has the notion that when a transport system is changed by engineering safety measures, road users do not respond only in the direction towards safety improvement but respond, in general, with three possible ways of behavioural adaptations, one of them towards more risk taking. Supported by illustrative examples, it also suggests that due to risk compensation, engineering safety measures alone are usually not sufficient, and, hopefully, carefully designed motivational safety measures can give us chances to modify road users' behaviour to make traffic safer.

Accidents, Traffic↗
PubMed1993

Differences in lingual vibrotactile thresholds of sensitivity using adjusted vs fixed methods of vibrator probe-contactor alignment.

The purpose of this study was to compare lingual vibrotactile thresholds of sensitivity obtained using individual subject adjustments of vibrator probe-contractor to lingual surface, with thresholds obtained using a fixed vibrator probe-contactor position across 30 subjects ranging in age from 18 to 26 yr. (M age = 20 yr.). Analysis showed minor (less than 5 dB SPL) differences in lingual vibrotactile thresholds of sensitivity between the two methods of vibrator probe-contactor alignment. For research purposes, the vibrator probe-contactor assembly should be adjusted to each individual's lingual surface, but for clinical-behavioral purposes, it might be sensible to use a fixed vibrator probe-contactor position across subjects, especially when performing research on young children, older adults, and the communicatively handicapped.

Adolescent↗
PubMed1992

Visual field differences in an object decision task.

Two experiments are reported which investigate hemispheric processing in an object decision task. Experiment 1 used 40 pictures of objects, and 40 pictures of nonobjects, and subjects decided manually whether each lateralized stimulus represented an object. Results indicated an interaction between visual field and response (yes versus no). There was a right visual field advantage for positive responses, but no difference between visual field for negative responses. Positive responses were faster than negative responses, and this effect was more marked for right visual field presentations. These results were replicated in a second experiment. The results are interpreted as reflecting a left hemisphere superiority at accessing stored structural descriptions of known objects. The possibility that left and right hemispheres use different methods of carrying out the task is also discussed.

Adult↗
PubMed1992

Lingual vibrotactile threshold and suprathreshold responses of normal-speaking black and white young adults.

A paradigm for studying oral sensory tactile function through use of single frequency vibration applied to the dorsal surface of the tongue was administered to a group of 10 young black women and 10 young white normal-speaking women. Analyses showed no differences between groups with regard to lingual vibrotactile threshold of sensitivity or suprathreshold magnitude-estimation scaling responses.

Adult↗
PubMed1992

Differences in lingual vibrotactile threshold shifts during magnitude-estimation scaling between normal-speaking children and children with articulation problems.

The purpose of this study was to investigate differences in function of the tactile sensory system between groups of normal-speaking children and children with articulation problems. This task was accomplished by studying possible tactile threshold shifts occurring during magnitude-estimation scaling of vibratory stimuli presented to the dorsal surface of the tongue. 10 normal-speaking children (M age = 7.8 yr.) and 9 children with articulation problems (M age = 7.5 yr.) participated. The normal-speaking children and articulatory defective children performed differently on the magnitude-estimation scaling task in which threshold was allowed to return to baseline after each stimulus presentation. These two groups of children also showed dissimilar threshold shifts for the suprathreshold intensities employed in the magnitude-estimation scaling.

Articulation Disorders↗
PubMed1991

Hemispheric differences in the processing of pictures of typical and atypical semantic category members.

In the following experiment, pictures of typical and atypical category members were categorised by subjects after presentation to either the left or right visual field. Three different categories were investigated. The results in part replicate a previous study by Zaidel (1987), who found an interaction between visual field and typicality. She suggested this result might reflect different conceptual organisations for each hemisphere. However, in the present study, the Visual Field x Typicality interaction was not evident in the two other categories investigated, and it is argued that any conclusion regarding conceptual organisation may be premature. Further work is needed to address the issue.

Adult↗
PubMed1990

How do readers know where to look next? Local information distributions influence eye fixations.

Skilled readers' eye movements were recorded as they inspected sentences in preparation for comprehension questions. The sentences were written around target words that had uneven distributions of information, in that the words were predictable, given either the first few letters or the last few letters. Some parts of these words can be described as being more important than others for successful word recognition, and the experiments asked whether inspection patterns reflect the uneven distributions. Four types of ten-letter word were used: words with highly redundant endings (e.g. engagement), with moderately redundant endings (e.g. repatriate), with moderately redundant beginnings (e.g. superstore), and words with informative beginnings and endings (e.g. amalgamate). Redundancy was defined operationally in terms of the number of possible completions of a word given the first few or last few letters. A highly redundant ending is therefore one that occurs frequently and cannot be used to identify the word. Words gaining just one fixation received this fixation nearer to the word's centre than in the case of the first fixation upon words gaining two fixations. The single fixation also had a longer duration, giving support to the notion of a convenient viewing location, which, when achieved, can lead to a net saving in inspection time. In the case of words with redundant endings gaining just one fixation, the fixation was nearer to the beginning of the word than in the case of words with informative endings, and this influence of word type upon the location of the first fixation was interpreted in favour of the parafoveal processing hypothesis of eye guidance during reading.

Adult↗
PubMed1989

Eye fixations are influenced by the distribution of information within words.

Reader's eye movements were monitored while they inspected isolated words in preparation for a synonym judgement task. The 10-letter words appeared on a screen near the point of fixation, with the first fixation being imposed near the beginning, or the centre, or the ending of the word. The words themselves had uneven distributions of information, in that the beginnings or the endings contained common sequences of letters in English. Three types of words were used: those with very redundant endings (e.g., yearningly), with moderately redundant endings (e.g., varnishing), and with moderately redundant beginnings (e.g., contravene). Redundancy was defined in terms of the total number of words in English which possess that particular sequence of five letters as the beginning or the ending. The experiments asked whether the convenient viewing location within a word varied according to the distribution of information, and whether the extent of redundancy in a word ending is reflected in the distribution of visual attention given to the word. The results were analysed separately for those cases where the reader made just two fixations upon the word before moving to the synonym task, and for those cases where the reader made exactly three fixations. These were the dominant fixation patterns. Evidence for the notion of a convenient viewing position consisted of long first fixations (when there were just two fixations), when this fixation was near the centre of the word. The distribution of information within the words did not influence the duration of the first fixation, although the duration of the gaze within each half-word did increase when more informative letter sequences were being inspected. The extent of redundancy was also seen to influence the inspection patterns, when a comparison was made between the two types of words with redundant endings. Words with very redundant endings received fewer fixations when the first fixation was at the beginning, and for words gaining exactly two fixations, the second fixation was shorter if the word had a very redundant ending.

Adult↗
PubMed1989

Reading long words embedded in sentences: informativeness of word halves affects eye movements.

The possibility was explored that the informativeness of a specific region within a word can influence eye movements during reading. In Experiment 1, words containing identifying information either toward the beginning or toward the end were displayed asymmetrically around the point of fixation so that the reader was initially presented with either the informative or noninformative zone. Words were read with shorter summed initial fixation time when the reading was started from the informative zone. In Experiments 2 and 3, the target words were presented in sentences that were to be comprehended. More attention was given to the informative endings of words than to redundant endings. The latter were also skipped more often. The duration of the first fixation was not affected by information distribution within the word, whereas the second fixation duration was. The results of these experiments lend good support to the hypothesis of immediate lexical control over fixation behavior and to the notion of a convenient viewing position.

Adult↗
PubMed1988

Information influences the pattern of eye fixations during sentence comprehension.

How does the pattern of eye fixation vary as an informative part of a word is encountered? If the processing of information lags behind the movement of the eyes, then we should expect no variation in the pattern; but if processing is immediate, then the movements of the reader's eyes should correspond to the distribution of information being inspected. An experiment is reported which examined the ways that the text ahead of the point of current fixation can be used to guide the eyes to future fixations, by monitoring fixations during a sentence comprehension task. The patterns of eye fixations upon words with uneven distributions of information (where, for example, words predictable from the sight of their first few letters but not from their last few letters are defined as containing informative beginnings) were observed, and it was found that more and longer fixations were produced when subjects looked at the informative parts of words, particularly at the informative endings of words. The results support the suggestion that eye movements are under the moment-to-moment control of cognitive mechanisms.

Adult↗
PubMed1985

Right-hemisphere interactions in picture-word processing.

The processing of pictures was investigated in three experiments which eliminated the response effects involved in naming. When a categorization task was used, clear advantages in response latency and accuracy were observed for left visual-field (LVF) presentations. This was in contrast to previous investigations which have used a naming task and which have reported right visual-field (RVF) advantages. When a distracting word was added to the display, the pattern of influence also changed from that reported previously. The use of naming tasks has indicated predominantly left-hemisphere effects, with demonstrations of interactions between pictures and words in the RVF. With a categorization task in Experiment 2, however, the only effective words were those related in meaning to the picture, and only when they were projected to the right hemisphere. The third experiment confirmed the LVF advantage for picture processing with masked displays, but found no reliable asymmetry with unmasked presentations. The pattern of semantic facilitation was also confirmed with the masked displays, but when the mask was removed an inhibition effect replaced the facilitation effect. These effects are interpreted as indicating that picture recognition is localized within the right cerebral hemisphere. It is suggested that the facilitating effect of related words is restricted to the left hemisphere because it is an effect upon recognition processes, whereas the inhibition effect reflects response competition. It is also suggested that previous reports of left-hemisphere interference effects are due to effects of response competition in naming tasks.

Adult↗
PubMed1984

The development of word recognition processes.

To observe the course of the development of automatic processes in word recognition, two experiments were performed in which a distracting word interacted with a target stimulus. In Expt 1 the subjects named a simple line drawing, and in Expt 2 they named a word appearing in a rectangle. The distracting word (i) was a semantic associate of the target stimulus, (ii) was graphemically similar to the name of the target, (iii) was phonemically similar to the name of the target, (iv) was unrelated in meaning, orthography and phonology, or (v) was replaced with an unpronounceable letter string. Three groups of subjects were tested. Skilled adult readers were compared with two groups of children. Matched groups of children were used, with similar ages (9-12 years old) and non-verbal spatial abilities, but dissimilar reading ages. All groups of subjects showed semantic interference and graphemic priming from the distractor word in Expt 1, and the children showed phonemic priming. In Expt 2, only the poor readers showed semantic interference, and no groups showed graphemic or phonemic effects. The sensitivity of the poor readers to the distractors indicates that the semantic, graphemic and phonemic codes of words are generated by these subjects, and that the difference in reading age between them and the good readers can be attributed to post-lexical processes such as text integration and articulatory planning and execution.

Age Factors↗