Are there differential word length effects in the two visual fields?

This study examined whether differential word length effects in the two visual fields imply hemisphere-dependent modes of word recognition. Length was defined as the number of constituent characters of Chinese foreign names (Experiments 1 and 2), as the number of constituent morphemes of three-character words (Experiments 3 and 4), and as that of constituent words of phrases (Experiments 5 and 6). Two types of experimental tasks were adopted, one required linguistic judgments on overall items (Experiments 1, 3, and 5) and the other was target detection tasks performed on the same set of stimuli (Experiments 2, 4, and 6). Five of the six experiments failed to find any kind of interaction between length and visual field. An interaction was observed only for the detection of characters embedded in foreign names, that is, when lexical access is least involved in the task, suggesting that word recognition plays a minimum role in the phenomenon. Other observations suggested that modes of word recognition are more frequency-dependent than hemisphere-dependent, and that Chinese compound words and phrases, although hardly distinguishable, do behave differently.     

Word frequency and laterality effects in lexical decision: right hemisphere mechanisms

Three experiments investigated the role of the right cerebral hemisphere in the word frequency effect observed in visual word recognition. The experiments examined lexical decisions to low and high frequency words as well as non-words in a divided visual field paradigm. Experiment 1 showed a significant word frequency effect only for left visual field presentation. Experiment 2 provided a partial replication of the results of Experiment 1 with a different set of words. In Experiment 3, case alternation was implemented to investigate a possible explanation of the findings. Results of the first experiment were replicated in the condition without case alternation. In the case-alternated condition, the word frequency effect was significant only for right visual field presentations. The present findings emphasize the need to consider that information processing strategies relevant to hemispheric asymmetries might account in part for the word frequency effect.     

Visual interaction: models, systems, prototypes. The Pictorial Computing Laboratory at the University of Rome “La Sapienza”

This paper reports on the research activities performed by the Pictorial Computing Laboratory at the University of Rome, La Sapienza, during the last 5 years. Such work, essentially is based on the study of humancomputer interaction, spans from metamodels of interaction down to prototypes of interactive systems for both synchronous multimedia communication and groupwork, annotation systems for web pages, also encompassing theoretical and practical issues of visual languages and environments also including pattern recognition algorithms. Some applications are also considered like e-learning and collaborative work.     

The modality shift effect and the effectiveness of warning signals in different modalities

Which is better, a visual or an auditory warning signal? Initial findings suggested that an auditory signal was more effective, speeding reaction to a target more than a visual warning signal, particularly at brief foreperiods [Bertelson, P., & Tisseyre, F. (1969). The time-course of preparation: confirmatory results with visual and auditory warning signals. Acta Psychologica, 30. In W.G. Koster (Ed.), Attention and Performance II (pp. 145-154); Davis, R., & Green, F. A. (1969). Intersensory differences in the effect of warning signals on reaction time. Acta Psychologica, 30. In W.G. Koster (Ed.), Attention and Performance II (pp. 155-167)]. This led to the hypothesis that an auditory signal is more alerting than a visual warning signal [Sanders, A. F. (1975). The foreperiod effect revisited. Quarterly Journal of Experimental Psychology, 27, 591-598; Posner, M. I., Nissen, M. J., & Klein, R. M. (1976). Visual dominance: an information-processing account of its origins and significance. Psychological Review, 83, 157-171]. Recently [Turatto, M., Benso, F., Galfano, G., & Umilta, C. (2002). Nonspatial attentional shifts between audition and vision. Journal of Experimental Psychology: Human Perception and Performance, 28, 628-639] found no evidence for an auditory warning signal advantage and showed that at brief foreperiods a signal in the same modality as the target facilitated responding more than a signal in a different modality. They accounted for this result in terms of the modality shift effect, with the signal exogenously recruiting attention to its modality, and thereby facilitating responding to targets arriving in the modality to which attention had been recruited. The present study conducted six experiments to understand the cause of these conflicting findings. The results suggest that an auditory warning signal is not more effective than a visual warning signal. Previous reports of an auditory superiority appear to have been caused by using different locations for the visual warning signal and visual target, resulting in the target arriving at an unattended location when the foreperiod was brief. Turatto et al.'s results were replicated with a modality shift effect at brief foreperiods. However, it is also suggested that previous measures of the modality shift effect may still have been confounded by a location cuing effect.     

The capacity of visual short-term memory within and between hemifields

Visual short-term memory (VSTM) and attention are both thought to have a capacity limit of four items [e.g. Luck, S. J., & Vogel, E. K. (1997). The capacity of visual working memory for features and conjunctions. Nature, 309, 279-281; Pylyshyn, Z. W., & Storm, R. W. (1988). Tracking multiple independent targets: evidence for a parallel tracking mechanism. Spatial Vision, 3, 179-197.]. Using the multiple object visual tracking paradigm (MOT), it has recently been shown that twice as many items can be simultaneously attended when they are separated between two visual fields compared to when they are all presented within the same hemifield [Alvarez, G. A., & Cavanagh, P. (2004). Independent attention resources for the left and right visual hemifields (Abstract). Journal of Vision, 4(8), 29a.]. Does VSTM capacity also increase when the items to be remembered are distributed between the two visual fields? The current paper investigated this central issue in two different tasks, namely a color and spatial location change detection task, in which the items were displayed either in the two visual fields or in the same hemifield. The data revealed that only memory capacity for spatial locations and not colors increased when the items were separated between the two visual fields. These findings support the view of VSTM as a chain of capacity limited operations where the spatial selection of stimuli, which dominates in both spatial location VSTM and MOT, occupies the first place and shows independence between the two fields.     

Interference effects demonstrate distinct roles for visual and motor imagery during the mental representation of human action

Four experiments were completed to characterize the utilization of visual imagery and motor imagery during the mental representation of human action. In Experiment 1, movement time functions for a motor imagery human locomotion task conformed to a speed-accuracy trade-off similar to Fitts' Law, whereas those for a visual imagery object motion task did not. However, modality-specific interference effects in Experiment 2 demonstrate visual and motor imagery as cooperative processes when the action represented is tied to visual coordinates in space. Biomechanic-specific motor interference effects found in Experiment 3 suggest one basis for separation of processing channels within motor imagery. Finally, in Experiment 4 representations of motor actions were found to be generated using only visual imagery under certain circumstances: namely, when the imaginer represented the motor action of another individual while placed at an opposing viewpoint. These results suggest that the modality of representation recruited to generate images of human action is dependent on the dynamic relationship between the individual, movement, and environment.     

The relationship between object files and conscious perception

Object files (OFs) are hypothesized mid-level representations which mediate our conscious perception of persisting objects-e.g. telling us 'which went where'. Despite the appeal of the OF framework, not previous research has directly explored whether OFs do indeed correspond to conscious percepts. Here we present at least one case wherein conscious percepts of 'which went where' in dynamic ambiguous displays diverge from the analogous correspondence computed by the OF system. Observers viewed a 'bouncing/streaming' display in which two identical objects moved such that they could have either bounced off or streamed past each other. We measured two dependent variables: (1) an explicit report of perceived bouncing or streaming; and (2) an implicit 'object-specific preview benefit' (OSPB), wherein a 'preview' of information on a specific object speeds the recognition of that information at a later point when it appears again on the same object (compared to when it reappears on a different object), beyond display-wide priming. When the displays were manipulated such that observers had a strong bias to perceive streaming (on over 95% of the trials), there was nevertheless a strong OSPB in the opposite direction-such that the object files appeared to have 'bounced' even though the percept 'streamed'. Given that OSPBs have been taken as a hallmark of the operation of object files, the five experiments reported here suggest that in at least some specialized (and perhaps ecologically invalid) cases, conscious percepts of 'which went where' in dynamic ambiguous displays can diverge from the mapping computed by the object-file system.     

The role of perception, language, and preference in the developmental acquisition of basic color terms

When learning basic color vocabulary, young children show a selective delay in the acquisition of brown and gray relative to other basic color terms. In this study, we first establish the robustness of this finding and then investigate the extent to which perception, language, and color preference may influence color conceptualization. Experimental tasks were designed to measure different aspects of perceptual color processing (discrimination and saliency), color preference and objective counts of color term frequency in preschool-directed language (books and mothers' speech) were used to compare the acquisition of three groups of colors: primary colors, secondary colors (orange, pink, and purple) that appear at the same time as the primary colors, and secondary colors (brown and gray) that appear late. Although our results suggest that perception does not directly shape young children's color term acquisition, we found that children prefer brown and gray significantly less than basic colors and that these color terms appear significantly less often in child-directed speech, suggesting that color preference, linguistic input, and developing color cognition may be linked.     

Development of preferences for the human body shape in infancy

Two studies investigated the development of infants' visual preferences for the human body shape. In Study 1, infants of 12, 15 and 18 months were tested in a standard preferential looking experiment, in which they were shown paired line drawings of typical and scrambled bodies. Results indicated that the 18-month-olds had a reliable preference for the scrambled body shapes over typical body shapes, while the younger infants did not show differential responding. In Study 2, 12- and 18-month-olds were tested with the same procedure, except that the typical and scrambled body stimuli were photographic images. The results of Study 2 again indicated that only the 18-month-olds had a reliable preference for the scrambled body shapes. This finding contrasts sharply with infants' precocious preferences for human faces, suggesting that infants' learning about human faces and human bodies follow different developmental trajectories.     

Lateralized effects of target location on reaction times when preparing for manual aiming at a visual target

To elucidate the temporal characteristics of information processing for motor action differing in complexity in relation to both perceptual and cognitive information processing, we investigated whether the reaction times (RTs) to a visual target would be affected by task complexity (finger lifting or manual aiming), pre-cueing (with a pre-cue or without a pre-cue), or target location (five horizontal positions). Using the right hand, seven right-handed subjects performed two tasks, finger lifting and manual aiming at a target, with or without a pre-cue. The pre-cue announced the location of the target to be presented. An ANOVA showed significant interactions between task and location and between pre-cue and location with no significant interaction between task and pre-cue, indicating that the task-location interaction does not depend on whether or not a pre-cue is given. The manual-aiming RTs were longer than the finger-lifting RTs, and the effects of the target location on the RTs differed for finger lifting and manual aiming. It can be assumed that the longer RTs of manual aiming reflect the time for information processing that is needed when preparing for the aiming action per se, which is an extra movement performed in addition to the simple initiation of finger lifting. Differential RTs (DRTs) calculated by subtracting the finger-lifting RTs from the aiming RTs were therefore examined. The DRTs significantly differed for target locations (i.e., a lateralized effect), with the DRTs for an ipsilateral target appearing to be significantly shorter than those for contralateral and central targets. The lateralized effect appearing on the DRTs may be mediated by the processing of visual-spatial information about visual targets as motor preparations are made for manual aiming.