Spatial compatibility effects on the same side of the body midline

Stimulus-response compatibility effects have been hypothesized to result (a) from a subject's innate tendency to respond in the direction of the source of stimulation, (b) from a correspondence between the spatial codes associated with the effector and the stimulus, or (c) from an attentional bias favoring the effector located in the same hemispace as the command signal. Two experiments were conducted to test these three hypotheses. In Experiment 1 the subjects were requested to make unimanual discriminative key-pressing responses to two light stimuli, both appearing to either the right or left of the fixation point. In one condition the two hands were in anatomical position (uncrossed); in the other they were crossed. The procedure of Experiment 2 was similar to that of Experiment 1 with the exception that both hands, always in an uncrossed position, were placed on the same side of the body midline (on the right or left). The results showed that the compatibility effect depends on a correspondence between the spatial codes associated with the location of the effector and the location of the command stimulus.     

Ultradian cyclicity in auditory and visual reaction time during long performance

24 subjects were tested to check the hypothesis proposed by Kleitman about a "basic rest-activity cycle". Reaction time tasks were delivered at 10-min. intervals for 320 min. Spectral density function analyses showed no significant periods within the limits of the cycle. Discussion concerns fulfilling assumptions of spectral analysis and Fisher's test.     

Egocentric and relative spatial codes in S-R compatibility

Summary It has been shown that spatial compatibility is due to a comparison between the spatial codes that describe stimulus and response positions. Such codes are often defined in right-left terms. There are, however, two types of right-left codes that can be used for describing a position in space. One is formed with relation to the egocentric axes and can be termed side, whereas the other is formed with relation to an external reference location and can be termed relative position. Five experiments were conducted to determine the role of these different codes in producing spatial compatibility effects. In Experiments 1 and 2 the position of the stimulus provided the relevant cue for choosing the correct response (i.e., the situation was typical of spatial compability proper), whereas in Experiments 3, 4, and 5 the stimulus provided a locational cue that was not necessary for choosing the correct response (i.e., the situation was typical of the Simon effect). The experimental manipulations concerned the task demands and the time elapsing between availability of the stimulus code and availability of the response code. The results showed that upon stimulus presentation, both stimulus codes (that concerning side and that concerning relative position) were formed, but experimental manipulations determined the one that was effective in yielding compatibility effects. When the task required the use of one type of code, then spatial compatibility depended on that code alone. When the two coding processes were separated in time, then spatial compatibility depended only on the code that was formed simultaneously with the response code.     

Poor hand-pointing to sounds in right brain-damaged patients: not just a problem of spatial-hearing

We asked 22 right brain-damaged (RBD) patients and 11 elderly healthy controls to perform hand-pointing movements to free-field unseen sounds, while modulating two non-auditory variables: the initial position of the responding hand (left, centre or right) and the presence or absence of task-irrelevant ambient vision. RBD patients suffering from visual neglect, unlike RBD patients without neglect and healthy controls, showed a systematic rightward error in sound localisation, which was modulated by the non-auditory variables. Localisation errors were exacerbated by initial hand-position to the right of the body-midline, and reduced by the leftwards initial hand-position. Moreover, for the visual neglect patients, mere presence of ambient vision worsened localisation errors. These results demonstrate that although hand-pointing to sounds has often been considered a straightforward approach to investigate sound-localisation abilities in brain-damaged patients, in some patients it may actually reveal localisation deficits that reflect a combination of impaired spatial-hearing and spatial biases from other sensory modalities (i.e., vision and proprioception).     

Foreground–background segmentation and attention: A change blindness study

One of the most debated questions in visual attention research is what factors affect the deployment of attention in the visual scene? Segmentation processes are influential factors, providing candidate objects for further attentional selection, and the relevant literature has concentrated on how figure–ground segmentation mechanisms influence visual attention. However, another crucial process, namely foreground–background segmentation, seems to have been neglected. By using a change blindness paradigm, we explored whether attention is preferentially allocated to the foreground elements or to the background ones. The results indicated that unless attention was voluntarily deployed to the background, large changes in the color of its elements remained unnoticed. In contrast, minor changes in the foreground elements were promptly reported. Differences in change blindness between the two regions of the display indicate that attention is, by default, biased toward the foreground elements. This also supports the phenomenal observations made by Gestaltists, who demonstrated the greater salience of the foreground than the background.     

The trajectory of a dot crossing a pattern of tilted lines is misperceived

The straight trajectory of a dot crossing a pattern of tilted lines is perceived as being sinusoidal. Manipulation of the size of the angle between the trajectory and the tilted lines, the velocity of the dot, and the distance between the tilted lines shows that the magnitude of the illusion is inversely proportional to the size of the incidence angle, to velocity, and to the distance between the lines. The illusion is interpreted as being the result of an integration process of local distortions occurring at the intersections with the tilted lines.     

Is there a modality effect? Evidence for visual recency and suffix effects

In Experiment 1, four groups of 16 subjects performed ordered recall of six-syllable lists in both suffix and nonsuffix conditions. Sequential presentation of the lists varied for each group. In the auditory presentation, the syllables were delivered from one location only and were read aloud by the subjects. For the visual, spatially nondistributed presentation, the syllables appeared in one location only and were read silently. For visual, spatially distributed presentations, the syllables were spread out either vertically or horizontally and were read silently. Very robust recency and suffix effects were found in the auditory presentation, as well as in visual, spatially distributed presentations. In Experiment 2, 16 subjects performed ordered recall of visually presented lists with the items spread out vertically and conflicting spatial and temporal orders. A reliable recency effect was found for the final block of trials. In Experiment 3, 16 subjects performed ordered recall in the same conditions as in Experiment 2, except that they were instructed to recall the temporal order in which the spatial positions would be filled in. A bow-shaped curve and a strong recency effect were obtained.     

Manual behavior, lateralization of manual skills and cognitive performance of preschool children

Direction and degree of manual specialization (functional asymmetry between the hands) on a pegboard task, and fine motor ability (total number of pegs inserted) of both hands were correlated with verbal and visuospatial performances for 47 preschool children. No significant differences were found between right-, and left-, and mixed-handers even though the best motor skills were shown by the 6 mixed-handed subjects, who also had the highest scores on cognitive tasks. Verbal and visuospatial performances were not correlated with degree or direction of manual specialization. They were instead correlated with the level of motor ability of both hands. Motor maturation should be viewed, then, as a process that implies a richer motor performance of both hands and could be interpreted as a more specific diagnostic parameter than the traditional indices of handedness in cognitive fields.     

Hyperbole,abstract motion and spatial knowledge: sequential versus simultaneous scanning

Hyperbole is an interesting trope in the perspective of Space Grammar, since it is related to the displacing of a limit (Lausberg in Elemente der literarischen Rhetorik. M.H. Verlag, Munchen 1967; see the Ancient Greek meaning ‘to throw over’ > ‘exaggerate’). Hyperbole semantic mechanisms are related to virtual scanning (Holmqvist and P?uciennik in Imagery in language. Peter Lang, Frankfurt am Main, pp 777–785, 2004). Basic concepts of SIZE and QUANTITY, related image-schemas (IS) and conceptual metaphors (UP IS MORE; IMPORTANT IS BIG: Lakoff 1987, Johnson 1987) are implied in hyperbole processing. The virtual scanning is the simulation of a perceptual domain (here, the vertically oriented space). The virtual limit is defined by expected values on the relevant scale. Since hyperbole is a form of intensification, its linguistic interest lies in cases involving the extremes of a scale, for which a limit can be determined (Schemann 1994). In this experimental study, we analyze the concept of ‘limit’ in terms of ‘abstract motion’ and ‘oriented space’ domains (Langacker 1990) with respect to hyperboles expressed by Italian Verbs of movement. The IS considered are PATH and SOURCE-PATH-GOAL. The latter corresponds to a virtual scale whose limit is arrived at, or overcome, in hyperboles.