The present study investigates the efficiency of haptic search facilitated by the division of the... more The present study investigates the efficiency of haptic search facilitated by the division of the searchable area. Previous studies have shown that scales provided around tactile maps for blind persons can shorten the search time for tactile symbols on the maps, but the optimum number of divisions has not been found. We conducted an experiment in which maps with different numbers of divisions were presented to blindfolded participants. The search times for tactile targets on the maps were measured and a movie that recorded searching behavior was analyzed. Our results indicate that scales with 3 × 4 divisions minimize search time, and the movie analysis reveals that this optimization is determined by the time of both scalecounting and target-searching. This finding elucidates the manner of human haptic search and should be utilized for the optimization of automated tactile map creation.
The perceived temporal order of external successive events does not always follow their physical ... more The perceived temporal order of external successive events does not always follow their physical temporal order. We examined the contribution of self-motion mechanisms in the perception of temporal order in the auditory modality. We measured perceptual biases in the judgment of the temporal order of two short sounds presented successively, while participants experienced visually induced self-motion (yaw-axis circular vection) elicited by viewing long-lasting large-field visual motion. In experiment 1, a pair of white-noise patterns was presented to participants at various stimulus-onset asynchronies through headphones, while they experienced visually induced self-motion. Perceived temporal order of auditory events was modulated by the direction of the visual motion (or self-motion). Specifically, the sound presented to the ear in the direction opposite to the visual motion (ie heading direction) was perceived prior to the sound presented to the ear in the same direction. Experiments...
In visual search tasks, the relative proportions of target-present and -absent trials have import... more In visual search tasks, the relative proportions of target-present and -absent trials have important effects on behavior. Miss error rates rise as target prevalence decreases (Wolfe, Horowitz, & Kenner, Nature 435, 439-440, 2005). At the same time, search termination times on target-absent trials become shorter (Wolfe & Van Wert, Current Biology 20, 121-124, 2010). These effects must depend on some implicit or explicit knowledge of the current prevalence. What is the nature of that knowledge? In Experiment 1, we conducted visual search tasks at three levels of prevalence (6%, 50%, and 94%) and analyzed performance as a function of "local prevalence," the prevalence over the last n trials. The results replicated the usual effects of overall prevalence but revealed only weak or absent effects of local prevalence. In Experiment 2, the overall prevalence in a block of trials was 20%, 50%, or 80%. However, a 100%-valid cue informed observers of the prevalence on the next trial. These explicit cues had a modest effect on target-absent RTs, but explicit expectation could not explain the full prevalence effect. We conclude that observers predict prevalence on the basis of an assessment of a relatively long prior history. Each trial contributes a small amount to that assessment, and this can be modulated but not overruled by explicit instruction.
Http Dx Doi Org 10 1162 Jocn_A_00262, Jun 21, 2012
From which regions of the brain do conscious representations of visual stimuli emerge? This is an... more From which regions of the brain do conscious representations of visual stimuli emerge? This is an important but controversial issue in neuroscience because some studies have reported a major role of the higher visual regions of the ventral pathway in conscious perception, whereas others have found neural correlates of consciousness as early as in the primary visual areas and in the thalamus. One reason for this controversy has been the difficulty in focusing on neural activity at the moment when conscious percepts are generated in the brain, excluding any bottom-up responses (not directly related to consciousness) that are induced by stimuli. In this study, we address this issue with a new approach that can induce a rapid change in conscious perception with little influence from bottom-up responses. Our results reveal that the first consciousness-related activity emerges from the higher visual region of the ventral pathway. However, this activity is rapidly diffused to the entire brain, including the early visual cortex. These results thus integrate previous "higher" and "lower" views on the emergence of neural correlates of consciousness, providing a new perspective for the temporal dynamics of consciousness.
A patch with one texture appears as a distinct perceptual entity within a background region with ... more A patch with one texture appears as a distinct perceptual entity within a background region with contrasting texture if their features differ adequately (texture segregation). If there is no pictorial depth cue such as size, the patch, which is a small closed region, may stand out. Incidentally, if two fields of random dots that are identical except for a slight shift in a region are presented in rapid alternation, the region appears as an entity reciprocating above the background (RDK). With these phenomena, a number of studies have attempted to reveal several types of perception such as texture, subjective contour, or motion. While Klymenko et al. (1989) reported that a flickering region appeared as a background when the temporal frequency was high, most studies have not focused on depth perception. This study investigates apparent depth of a patch of dynamic random noise within a static field of random dots. Dynamic random noise involves spatiotemporal changes and stimulates moti...
A quantitative analysis was made to clarify the ability of human observers to detect a line of a ... more A quantitative analysis was made to clarify the ability of human observers to detect a line of a unique orientation against a background of lines of a different orientation. Results of a psychophysical experiment indicated that the performance of correct judgments increased with the number of adjacent lines under the control of lateral masking effects. A model for decision making was formulated to simulate the results. The consistence between the experiment and the simulation suggested; (1) the human visual system uses differences between adjacent lines of orientations, (2) it integrates the orientation differences into a global percept by the Bayesian inference rule
Examined the effects of a concurrent alphanumeric discrimination task requiring the spatial selec... more Examined the effects of a concurrent alphanumeric discrimination task requiring the spatial selective attention to various motion aftereffects (MAEs). Three Ss with normal or corrected-to-normal vision took part in 3 experiments. The effects of attentional tasks on the MAEs depended on the type of MAE and on the size of the adapting stimulus. For the small adapting stimulus, the strength of the simple translation MAE was attenuated by the concurrent tasks, and the MAE in depth or rotation MAE were not. Using the large stimulus, however, the effects of attention were not observed in all of MAEs. Results suggest that MAEs are not always switched off by selective attention. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
In visual search tasks, the ratio of target-present to target-absent trials has an important effe... more In visual search tasks, the ratio of target-present to target-absent trials has an important effect on miss rates. The low prevalence effect indicates that we are more likely to miss a target when it occurs rarely rather than frequently. In this study, we examined whether probability cueing modulates the miss rate and the observer's criterion. The results indicated that probability cueing affects miss rates, the average observer's criterion, and reaction time for target-absent trials. These results clearly demonstrate that probability cueing modulates two parameters (i.e., the decision criterion and the quitting threshold) and produces a low prevalence effect. Taken together, the current study and previous studies suggest that the miss rate is not just affected by global prevalence; it is also affected by probability cueing.
The present study investigates the efficiency of haptic search facilitated by the division of the... more The present study investigates the efficiency of haptic search facilitated by the division of the searchable area. Previous studies have shown that scales provided around tactile maps for blind persons can shorten the search time for tactile symbols on the maps, but the optimum number of divisions has not been found. We conducted an experiment in which maps with different numbers of divisions were presented to blindfolded participants. The search times for tactile targets on the maps were measured and a movie that recorded searching behavior was analyzed. Our results indicate that scales with 3 × 4 divisions minimize search time, and the movie analysis reveals that this optimization is determined by the time of both scalecounting and target-searching. This finding elucidates the manner of human haptic search and should be utilized for the optimization of automated tactile map creation.
The perceived temporal order of external successive events does not always follow their physical ... more The perceived temporal order of external successive events does not always follow their physical temporal order. We examined the contribution of self-motion mechanisms in the perception of temporal order in the auditory modality. We measured perceptual biases in the judgment of the temporal order of two short sounds presented successively, while participants experienced visually induced self-motion (yaw-axis circular vection) elicited by viewing long-lasting large-field visual motion. In experiment 1, a pair of white-noise patterns was presented to participants at various stimulus-onset asynchronies through headphones, while they experienced visually induced self-motion. Perceived temporal order of auditory events was modulated by the direction of the visual motion (or self-motion). Specifically, the sound presented to the ear in the direction opposite to the visual motion (ie heading direction) was perceived prior to the sound presented to the ear in the same direction. Experiments...
In visual search tasks, the relative proportions of target-present and -absent trials have import... more In visual search tasks, the relative proportions of target-present and -absent trials have important effects on behavior. Miss error rates rise as target prevalence decreases (Wolfe, Horowitz, & Kenner, Nature 435, 439-440, 2005). At the same time, search termination times on target-absent trials become shorter (Wolfe & Van Wert, Current Biology 20, 121-124, 2010). These effects must depend on some implicit or explicit knowledge of the current prevalence. What is the nature of that knowledge? In Experiment 1, we conducted visual search tasks at three levels of prevalence (6%, 50%, and 94%) and analyzed performance as a function of "local prevalence," the prevalence over the last n trials. The results replicated the usual effects of overall prevalence but revealed only weak or absent effects of local prevalence. In Experiment 2, the overall prevalence in a block of trials was 20%, 50%, or 80%. However, a 100%-valid cue informed observers of the prevalence on the next trial. These explicit cues had a modest effect on target-absent RTs, but explicit expectation could not explain the full prevalence effect. We conclude that observers predict prevalence on the basis of an assessment of a relatively long prior history. Each trial contributes a small amount to that assessment, and this can be modulated but not overruled by explicit instruction.
Http Dx Doi Org 10 1162 Jocn_A_00262, Jun 21, 2012
From which regions of the brain do conscious representations of visual stimuli emerge? This is an... more From which regions of the brain do conscious representations of visual stimuli emerge? This is an important but controversial issue in neuroscience because some studies have reported a major role of the higher visual regions of the ventral pathway in conscious perception, whereas others have found neural correlates of consciousness as early as in the primary visual areas and in the thalamus. One reason for this controversy has been the difficulty in focusing on neural activity at the moment when conscious percepts are generated in the brain, excluding any bottom-up responses (not directly related to consciousness) that are induced by stimuli. In this study, we address this issue with a new approach that can induce a rapid change in conscious perception with little influence from bottom-up responses. Our results reveal that the first consciousness-related activity emerges from the higher visual region of the ventral pathway. However, this activity is rapidly diffused to the entire brain, including the early visual cortex. These results thus integrate previous "higher" and "lower" views on the emergence of neural correlates of consciousness, providing a new perspective for the temporal dynamics of consciousness.
A patch with one texture appears as a distinct perceptual entity within a background region with ... more A patch with one texture appears as a distinct perceptual entity within a background region with contrasting texture if their features differ adequately (texture segregation). If there is no pictorial depth cue such as size, the patch, which is a small closed region, may stand out. Incidentally, if two fields of random dots that are identical except for a slight shift in a region are presented in rapid alternation, the region appears as an entity reciprocating above the background (RDK). With these phenomena, a number of studies have attempted to reveal several types of perception such as texture, subjective contour, or motion. While Klymenko et al. (1989) reported that a flickering region appeared as a background when the temporal frequency was high, most studies have not focused on depth perception. This study investigates apparent depth of a patch of dynamic random noise within a static field of random dots. Dynamic random noise involves spatiotemporal changes and stimulates moti...
A quantitative analysis was made to clarify the ability of human observers to detect a line of a ... more A quantitative analysis was made to clarify the ability of human observers to detect a line of a unique orientation against a background of lines of a different orientation. Results of a psychophysical experiment indicated that the performance of correct judgments increased with the number of adjacent lines under the control of lateral masking effects. A model for decision making was formulated to simulate the results. The consistence between the experiment and the simulation suggested; (1) the human visual system uses differences between adjacent lines of orientations, (2) it integrates the orientation differences into a global percept by the Bayesian inference rule
Examined the effects of a concurrent alphanumeric discrimination task requiring the spatial selec... more Examined the effects of a concurrent alphanumeric discrimination task requiring the spatial selective attention to various motion aftereffects (MAEs). Three Ss with normal or corrected-to-normal vision took part in 3 experiments. The effects of attentional tasks on the MAEs depended on the type of MAE and on the size of the adapting stimulus. For the small adapting stimulus, the strength of the simple translation MAE was attenuated by the concurrent tasks, and the MAE in depth or rotation MAE were not. Using the large stimulus, however, the effects of attention were not observed in all of MAEs. Results suggest that MAEs are not always switched off by selective attention. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
In visual search tasks, the ratio of target-present to target-absent trials has an important effe... more In visual search tasks, the ratio of target-present to target-absent trials has an important effect on miss rates. The low prevalence effect indicates that we are more likely to miss a target when it occurs rarely rather than frequently. In this study, we examined whether probability cueing modulates the miss rate and the observer's criterion. The results indicated that probability cueing affects miss rates, the average observer's criterion, and reaction time for target-absent trials. These results clearly demonstrate that probability cueing modulates two parameters (i.e., the decision criterion and the quitting threshold) and produces a low prevalence effect. Taken together, the current study and previous studies suggest that the miss rate is not just affected by global prevalence; it is also affected by probability cueing.
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