Takeo Watanabe

Publications (50)379.47 Total impact

• Article: Perceptual learning and aging: improved performance for low-contrast motion discrimination.

  Jeffrey D Bower, Takeo Watanabe, George J Andersen
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  ABSTRACT: Previous research has shown age-related differences in discriminating motion at different levels of contrast (Betts et al., 2005, 2009, 2012). A surprising result of this research is that older as compared to younger observers showed improved performance in detecting motion of large high-contrast stimuli suggesting age-related differences in center-surround antagonism. In the present study we examined whether perceptual learning methods could be used to improve motion discrimination performance for older individuals under high- and low-contrast conditions. The stimuli were centrally presented Gaussian filtered sine-wave gratings (Gabors) that were either 5° or 0.7° diameter with contrast of 0.92, 0.22, or 0.028. Older and younger participants received 3 days of training. The task was to identify if the motion direction was leftward or rightward. Duration thresholds for motion discrimination were derived using two randomly interleaved staircases and compared between pre-/post-test sessions. Both older and younger subjects showed lower duration thresholds as a result of training. The improved performance, for older subjects, due to training was observed for all size and contrast conditions, with training with small low-contrast stimuli resulting in a 23% improvement in motion discrimination performance. Older observers, as compared to younger observers, did show evidence of decreased spatial suppression across all contrast levels. These results suggest that perceptual learning techniques are effective for improving motion discrimination performance, especially for conditions that are difficult for older individuals.
  Frontiers in psychology. 01/2013; 4:66.
• Source

  Available from: pnas.org

  Article: Resetting capacity limitations revealed by long-lasting elimination of attentional blink through training.

  Hoon Choi, Li-Hung Chang, Kazuhisa Shibata, Yuka Sasaki, Takeo Watanabe
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  ABSTRACT: As with other cognitive phenomena that are based upon the capacity limitations of visual processing, it is thought that attentional blink (AB) cannot be eliminated, even after extensive training. We report in this paper that just 1 h of specific attentional training can completely eliminate AB, and that this effect is robust enough to persist for a few months after training. Results of subsequent behavioral and functional magnetic resonance imaging (fMRI) experiments indicate that this learning effect is associated with improvements in temporal resolution, which are mainly due to processing in the prefrontal areas. Contrary to prior wisdom, we conclude that capacity limitations can be overcome by short-term training.
  Proceedings of the National Academy of Sciences 07/2012; 109(30):12242-7. · 9.68 Impact Factor
• Article: Preference suppression caused by misattribution of task-irrelevant subliminal motion.

  Kazuhisa Shibata, Takeo Watanabe
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  ABSTRACT: It is well known that subjects tend to misattribute task-irrelevant signals, incorporating them into the information on which a decision is made. Such misattribution has been reported to originate only from a social or a cognitive stage of information processing. However, we provide the initial evidence that misattribution also originates at a lower, visuomotor stage. This type of misattribution occurs only when subjects do not notice a visuomotor conflict. Misattribution at a social or a cognitive stage facilitates decision-making if the misattributed information is consistent with the decision and impedes decision-making if the information is in conflict with the decision. However, misattribution originating at a visuomotor stage only impedes decision-making, suggesting a fundamental difference between the mechanisms for the two types of misattribution. Furthermore, misattribution effects that originate in a visuomotor interaction stage also affect subjective preference ratings, suggesting that the misattribution exerts an influence on global brain processing.
  Proceedings of the Royal Society B: Biological Sciences 06/2012; 279(1742):3443-8. · 5.41 Impact Factor
• Article: Monocular deprivation boosts long-term visual plasticity.

  Kazuhisa Shibata, Mitsuo Kawato, Takeo Watanabe, Yuka Sasaki
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  ABSTRACT: Monocular deprivation (MD) has been widely used to measure plasticity in the early visual system [1]. It is widely known that during an early critical period of an observer's life, the ocular dominance in the primary visual cortex is severely disrupted when measured immediately after the offset of MD. In contrast, hardly any change was observed when MD is conducted after the critical period [2]. Here we report that long-term plasticity occurred significantly more rapidly with the non-deprived eye than with the deprived eye of human adults when induced by training on a visual task conducted after three-day MD. Thus, the present results challenge the long-standing view that MD has no long-term influence on the visual function of normal adults.
  Current biology: CB 05/2012; 22(9):R291-2. · 10.99 Impact Factor
• Article: Perceptual learning solely induced by feedback.

  Hoon Choi, Takeo Watanabe
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  ABSTRACT: Although feedback is considered to be an important factor in perceptual learning (PL), its role is normally considered limited to facilitation, rather than direct inducement, of PL. Recent studies, however, have suggested feedback to be more actively involved in the inducement of PL. The current study demonstrates an even more significant role for feedback in PL: feedback can evoke PL of a feature without any bottom-up processing of that feature. We use a "fake feedback" method, in which the feedback is related to an arbitrarily chosen feature, rather than actual performance. We find evidence of PL with this fake feedback method both when the learned feature is absent from the visual stimulus (Experiment 1) and when it conflicts with the visual stimulus (Experiment 2). We call this "feedback-based PL," in contrast with the classical "exposure-based PL." We find that feedback-based PL and exposure-based PL can occur independently of each other even while occurring in the same paradigm. These results suggest that feedback not only facilitates PL that is evoked by bottom-up information, but that it can directly induce PL, where such feedback-based PL occurs independently of exposure-based PL.
  Vision research 01/2012; 61:77-82. · 2.29 Impact Factor
• Article: Is perceptual learning associated with changes in a sensory region?

  Hoon Choi, Takeo Watanabe
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  ABSTRACT: Perceptual learning is defined as long-term improvement in perceptual abilities as a result of perceptual experiences. It is controversial as to whether perceptual learning is associated with changes in a sensory region of the brain or not. Here, we review research that supports, or otherwise, the sensory change hypothesis and discuss what needs to be done in the future to answer this question more definitively.
  F1000 Biology Reports 01/2012; 4:24.
• Article: Decoding Reveals Plasticity in V3A as a Result of Motion Perceptual Learning.

  Kazuhisa Shibata, Li-Hung Chang, Dongho Kim, José E Náñez, Yukiyasu Kamitani, Takeo Watanabe, Yuka Sasaki
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  ABSTRACT: Visual perceptual learning (VPL) is defined as visual performance improvement after visual experiences. VPL is often highly specific for a visual feature presented during training. Such specificity is observed in behavioral tuning function changes with the highest improvement centered on the trained feature and was originally thought to be evidence for changes in the early visual system associated with VPL. However, results of neurophysiological studies have been highly controversial concerning whether the plasticity underlying VPL occurs within the visual cortex. The controversy may be partially due to the lack of observation of neural tuning function changes in multiple visual areas in association with VPL. Here using human subjects we systematically compared behavioral tuning function changes after global motion detection training with decoded tuning function changes for 8 visual areas using pattern classification analysis on functional magnetic resonance imaging (fMRI) signals. We found that the behavioral tuning function changes were extremely highly correlated to decoded tuning function changes only in V3A, which is known to be highly responsive to global motion with human subjects. We conclude that VPL of a global motion detection task involves plasticity in a specific visual cortical area.
  PLoS ONE 01/2012; 7(8):e44003. · 4.09 Impact Factor
• Article: Perceptual learning incepted by decoded fMRI neurofeedback without stimulus presentation.

  Kazuhisa Shibata, Takeo Watanabe, Yuka Sasaki, Mitsuo Kawato
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  ABSTRACT: It is controversial whether the adult primate early visual cortex is sufficiently plastic to cause visual perceptual learning (VPL). The controversy occurs partially because most VPL studies have examined correlations between behavioral and neural activity changes rather than cause-and-effect relationships. With an online-feedback method that uses decoded functional magnetic resonance imaging (fMRI) signals, we induced activity patterns only in early visual cortex corresponding to an orientation without stimulus presentation or participants' awareness of what was to be learned. The induced activation caused VPL specific to the orientation. These results suggest that early visual areas are so plastic that mere inductions of activity patterns are sufficient to cause VPL. This technique can induce plasticity in a highly selective manner, potentially leading to powerful training and rehabilitative protocols.
  Science 12/2011; 334(6061):1413-5. · 31.20 Impact Factor
• Article: Performance Dip in motor response induced by task-irrelevant weaker coherent visual motion signals.

  Yuko Yotsumoto, Aaron R Seitz, Shinsuke Shimojo, Masamichi Sakagami, Takeo Watanabe, Yuka Sasaki
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  ABSTRACT: The Performance Dip is a newly characterized behavioral phenomenon, where, paradoxically, a weaker task-irrelevant visual stimulus causes larger disturbances on the accuracy of a main letter identification task than a stronger stimulus does. Understanding mechanisms of the Performance Dip may provide insight into unconsciousness behavior. Here, we investigated the generalization of the Performance Dip. Specifically, we tested whether the Performance Dip occurs in a motion-related Simon task, and if so, whether the Performance Dip involves the same brain region, that is, the dorsolateral prefrontal cortex (DLPFC), previously implicated in the Performance Dip, or the supplementary motor area (SMA) and pre-SMA, implicated in a motion-related Simon Task. Subjects made manual directional responses according to the color of stochastic moving dots while ignoring the global direction of moving dots, which could be either congruent or incongruent to the response appropriate to the main task. We found that weak incongruent task-irrelevant stimuli caused a Performance Dip, in which the SMA and pre-SMA, rather than DLPFC, played critical roles. Our results suggest a possible common brain mechanism across different neural circuits, in which weak, but not strong, task-irrelevant information is free from inhibition and intrudes into neural circuits relevant to the main task.
  Cerebral Cortex 09/2011; 22(8):1887-93. · 6.54 Impact Factor
• Article: Accounting for speed-accuracy tradeoff in perceptual learning.

  Charles C Liu, Takeo Watanabe
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  ABSTRACT: In the perceptual learning (PL) literature, researchers typically focus on improvements in accuracy, such as d'. In contrast, researchers who investigate the practice of cognitive skills focus on improvements in response times (RT). Here, we argue for the importance of accounting for both accuracy and RT in PL experiments, due to the phenomenon of speed-accuracy tradeoff (SAT): at a given level of discriminability, faster responses tend to produce more errors. A formal model of the decision process, such as the diffusion model, can explain the SAT. In this model, a parameter known as the drift rate represents the perceptual strength of the stimulus, where higher drift rates lead to more accurate and faster responses. We applied the diffusion model to analyze responses from a yes-no coherent motion detection task. The results indicate that observers do not use a fixed threshold for evidence accumulation, so changes in the observed accuracy may not provide the most appropriate estimate of learning. Instead, our results suggest that SAT can be accounted for by a modeling approach, and that drift rates offer a promising index of PL.
  Vision research 09/2011; 61:107-14. · 2.29 Impact Factor
• Article: Spatial shifts of audio-visual interactions by perceptual learning are specific to the trained orientation and eye.

  Melissa A Batson, Anton L Beer, Aaron R Seitz, Takeo Watanabe
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  ABSTRACT: A large proportion of the human cortex is devoted to visual processing. Contrary to the traditional belief that multimodal integration takes place in multimodal processing areas separate from visual cortex, several studies have found that sounds may directly alter processing in visual brain areas. Furthermore, recent findings show that perceptual learning can change the perceptual mechanisms that relate auditory and visual senses. However, there is still a debate about the systems involved in cross-modal learning. Here, we investigated the specificity of audio-visual perceptual learning. Audio-visual cuing effects were tested on a Gabor orientation task and an object discrimination task in the presence of lateralised sound cues before and after eight-days of cross-modal task-irrelevant perceptual learning. During training, the sound cues were paired with visual stimuli that were misaligned at a proximal (trained) visual field location relative to the sound. Training was performed with one eye patched and with only one Gabor orientation. Consistent with previous findings we found that cross-modal perceptual training shifted the audio-visual cueing effect towards the trained retinotopic location. However, this shift in audio-visual tuning was only observed for the trained stimulus (Gabors), at the trained orientation, and in the trained eye. This specificity suggests that multimodal interactions resulting from cross-modal (audio-visual) task-irrelevant perceptual learning involves so-called unisensory visual processing areas in humans. Our findings provide further support for recent anatomical and physiological findings that suggest relatively early interactions in cross-modal processing.
  Seeing and perceiving 01/2011; 24(6):579-94. · 1.18 Impact Factor
• Article: Multisensory perceptual learning reshapes both fast and slow mechanisms of crossmodal processing.

  Anton L Beer, Melissa A Batson, Takeo Watanabe
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  ABSTRACT: Previous research has shown that sounds facilitate perception of visual patterns appearing immediately after the sound but impair perception of patterns appearing after some delay. Here we examined the spatial gradient of the fast crossmodal facilitation effect and the slow inhibition effect in order to test whether they reflect separate mechanisms. We found that crossmodal facilitation is only observed at visual field locations overlapping with the sound, whereas crossmodal inhibition affects the whole hemifield. Furthermore, we tested whether multisensory perceptual learning with misaligned audio-visual stimuli reshapes crossmodal facilitation and inhibition. We found that training shifts crossmodal facilitation towards the trained location without changing its range. By contrast, training narrows the range of inhibition without shifting its position. Our results suggest that crossmodal facilitation and inhibition reflect separate mechanisms that can both be reshaped by multisensory experience even in adult humans. Multisensory links seem to be more plastic than previously thought.
  Cognitive Affective & Behavioral Neuroscience 11/2010; 11(1):1-12. · 3.57 Impact Factor
• Article: Temporally extended dopamine responses to perceptually demanding reward-predictive stimuli.

  Kensaku Nomoto, Wolfram Schultz, Takeo Watanabe, Masamichi Sakagami
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  ABSTRACT: Midbrain dopamine neurons respond to reward-predictive stimuli. In the natural environment reward-predictive stimuli are often perceptually complicated. Thus, to discriminate one stimulus from another, elaborate sensory processing is necessary. Given that previous studies have used simpler types of reward-predictive stimuli, it has yet to be clear whether and, if so, how dopamine neurons obtain reward information from perceptually complicated stimuli. To investigate this, we recorded the activities of monkey dopamine neurons while they were performing discrimination between two coherent motion directions in random-dot motion stimuli. These coherent directions were paired with different magnitudes of reward. We found that dopamine neurons showed reward-predictive responses to random-dot motion stimuli. Moreover, dopamine neurons showed temporally extended activity correlated with changes in reward prediction (i.e., reward prediction error) from coarse to fine scales between initial motion detection and subsequent motion discrimination phases. Noticeably, dopamine reward-predictive responses became differential in a later phase than previously reported. This response pattern was consistent with the time course of processing required for the estimation of expected reward value that parallels the motion direction discrimination processing. The results demonstrate that dopamine neurons are able to reflect the reward value of perceptually complicated stimuli, and suggest that dopamine neurons use the moment-to-moment reward prediction associated with environmental stimuli to compute a reward prediction error.
  Journal of Neuroscience 08/2010; 30(32):10692-702. · 7.11 Impact Factor
• Source

  Available from: usc.edu

  Article: Perceptual learning: cortical changes when cats learn a new trick.

  Yuka Sasaki, Joshua Gold, Takeo Watanabe
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  ABSTRACT: A new study has found that the tuning properties of neurons in the primary visual cortex of cats change as they learn an orientation-discrimination task, casting new light on the neuronal basis of perceptual learning.
  Current biology: CB 07/2010; 20(13):R557-8. · 10.99 Impact Factor
• Source

  Available from: Eleni L Vlahou

  Article: Unattended exposure to components of speech sounds yields same benefits as explicit auditory training.

  Aaron R Seitz, Athanassios Protopapas, Yoshiaki Tsushima, Eleni L Vlahou, Simone Gori, Stephen Grossberg, Takeo Watanabe
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  ABSTRACT: Learning a second language as an adult is particularly effortful when new phonetic representations must be formed. Therefore the processes that allow learning of speech sounds are of great theoretical and practical interest. Here we examined whether perception of single formant transitions, that is, sound components critical in speech perception, can be enhanced through an implicit task-irrelevant learning procedure that has been shown to produce visual perceptual learning. The single-formant sounds were paired at subthreshold levels with the attended targets in an auditory identification task. Results showed that task-irrelevant learning occurred for the unattended stimuli. Surprisingly, the magnitude of this learning effect was similar to that following explicit training on auditory formant transition detection using discriminable stimuli in an adaptive procedure, whereas explicit training on the subthreshold stimuli produced no learning. These results suggest that in adults learning of speech parts can occur at least partially through implicit mechanisms.
  Cognition 03/2010; 115(3):435-43. · 3.16 Impact Factor
• Article: Perceptual learning, aging, and improved visual performance in early stages of visual processing.

  George J Andersen, Rui Ni, Jeffrey D Bower, Takeo Watanabe
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  ABSTRACT: In the present study, we examined whether perceptual learning methods can be used to improve performance of older individuals. Subjects performed a texture discrimination task in the peripheral visual field and a letter discrimination task in central vision. The SOA threshold was derived by presenting a mask following the stimuli. Older subjects (age greater than 65 years) were either trained for 2 days using near threshold stimuli (experimental group) or were trained with the task with supra-threshold stimuli (older control group). The experimental group showed significant improvement in the task as a result of training whereas the older control group showed no significant improvement. The improved performance post-training equaled that of a younger control group and was maintained for at least 3 months. The results of two additional experiments indicate that the improved performance was not due to changes in divided attention, that the effect of perceptual learning was location specific, and that the pattern of learning was similar to that of younger subjects. These results indicate that perceptual learning with near threshold training can be used to improve visual performance among older individuals, that the improvements are not the result of practice with the visual task, and that the improvements do not transfer to non-trained locations.
  Journal of Vision 01/2010; 10(13):4. · 3.38 Impact Factor
• Article: Advances in visual perceptual learning and plasticity.

  Yuka Sasaki, Jose E Nanez, Takeo Watanabe
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  ABSTRACT: Visual perceptual learning (VPL) is defined as a long-term improvement in performance on a visual task. In recent years, the idea that conscious effort is necessary for VPL to occur has been challenged by research suggesting the involvement of more implicit processing mechanisms, such as reinforcement-driven processing and consolidation. In addition, we have learnt much about the neural substrates of VPL and it has become evident that changes in visual areas and regions beyond the visual cortex can take place during VPL.
  Nature Reviews Neuroscience 12/2009; 11(1):53-60. · 26.48 Impact Factor
• Article: 3D surface perception from motion involves a temporal-parietal network.

  Anton L Beer, Takeo Watanabe, Rui Ni, Yuka Sasaki, George J Andersen
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  ABSTRACT: Previous research has suggested that three-dimensional (3D) structure-from-motion (SFM) perception in humans involves several motion-sensitive occipital and parietal brain areas. By contrast, SFM perception in nonhuman primates seems to involve the temporal lobe including areas MT, MST and FST. The present functional magnetic resonance imaging study compared several motion-sensitive regions of interest including the superior temporal sulcus (STS) while human observers viewed horizontally moving dots that defined either a 3D corrugated surface or a 3D random volume. Low-level stimulus features such as dot density and velocity vectors as well as attention were tightly controlled. Consistent with previous research we found that 3D corrugated surfaces elicited stronger responses than random motion in occipital and parietal brain areas including area V3A, the ventral and dorsal intraparietal sulcus, the lateral occipital sulcus and the fusiform gyrus. Additionally, 3D corrugated surfaces elicited stronger activity in area MT and the STS but not in area MST. Brain activity in the STS but not in area MT correlated with interindividual differences in 3D surface perception. Our findings suggest that area MT is involved in the analysis of optic flow patterns such as speed gradients and that the STS in humans plays a greater role in the analysis of 3D SFM than previously thought.
  European Journal of Neuroscience 09/2009; 30(4):703-13. · 3.63 Impact Factor
• Article: Interference and feature specificity in visual perceptual learning.

  Yuko Yotsumoto, Li-Hung Chang, Takeo Watanabe, Yuka Sasaki
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  ABSTRACT: Perceptual learning (PL) often shows specificity to a trained feature. We investigated whether feature specificity is related to disruption in PL using the texture discrimination task (TDT), which shows learning specificity to background element but not to target element. Learning was disrupted when orientations of background elements were changed in two successive training sessions (interference) but not in a random order from trial to trial (roving). The presentation of target elements seemed to have reversed effect; learning occurred in two-parts training but not with roving. These results suggest that interference in TDT is feature specific while disruption by roving is not.
  Vision research 09/2009; 49(21):2611-23. · 2.29 Impact Factor
• Article: The phenomenon of task-irrelevant perceptual learning.

  Aaron R Seitz, Takeo Watanabe
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  ABSTRACT: Task-irrelevant perceptual learning (TIPL) has captured a growing interest in the field of perceptual learning. The basic phenomenon is that stimulus features that are irrelevant to a subject's task (i.e. convey no useful information to that task) can be learned due to their consistent presentation during task-performance. Here we review recent research on TIPL and focus on two key aspects of TIPL; (1) the mechanisms gating learning in TIPL, and (2) what is learned through TIPL. We show that TIPL is gated by learning signals that are triggered from task processing or by rewards. These learning signals operate to enhance processing of individual stimulus features and appear to result in plasticity in early stages of visual processing. Furthermore, we discuss recent research that demonstrates that TIPL is not in opposition to theories of attention but instead that TIPL operates in concert with attention. Where attentional learning is best to enhance (or suppress) processing of stimuli of known task relevance, TIPL serves to enhance perception of stimuli that are originally inadequately processed by the brain.
  Vision research 09/2009; 49(21):2604-10. · 2.29 Impact Factor