Perceptual Deterioration Research Articles

Daily dose-response from short-term monocular deprivation in adult humans.

Short-term monocular deprivation (MD) shifts sensory eye balance in favour of the previously deprived eye. The effect of MD on eye balance is significant but brief in adult humans. Recently, researchers and clinicians have attempted to implement MD in clinical settings for adults with impaired binocular vision. Although the effect of MD has been studied in detail in single-session protocols, what is not known is whether the effect of MD on eye balance deteriorates after repeated periods of MD (termed 'perceptual deterioration'). An answer to this question is relevant for two reasons. Firstly, the effect of MD (i.e., dose-response) should not decrease with repeated use if MD is to be used therapeutically (e.g., daily for weeks). Second, it bears upon the question of whether the neural basis of the effects of MD and contrast adaptation, a closely related phenomenon, is the same. The sensory change from contrast adaptation depends on recent experience. If the observer has recently experienced the same adaptation multiple times for consecutive days, then the adaptation effect will be smaller because contrast adaptation exhibits perceptual deterioration, so it is of interest to know if the effects of MD follow suit. This study measured the effect of 2-h MD for seven consecutive days on binocular balance of 15 normally sighted adults. We found that the shift in eye balance from MD stayed consistent, showing no signs of deterioration after subjects experienced multiple periods of MD. This finding shows no loss of effectiveness of repeated daily doses of MD if used therapeutically to rebalance binocular vision in otherwise normal individuals. Furthermore, ocular dominance plasticity, which is the basis of the effects of short-term MD, does not seem to share the property of 'perceptual deterioration' with contrast adaptation, suggesting different neural bases for these two related phenomena.

On the particular vulnerability of face recognition to aging: a review of three hypotheses.

Age-related face recognition deficits are characterized by high false alarms to unfamiliar faces, are not as pronounced for other complex stimuli, and are only partially related to general age-related impairments in cognition. This paper reviews some of the underlying processes likely to be implicated in theses deficits by focusing on areas where contradictions abound as a means to highlight avenues for future research. Research pertaining to the three following hypotheses is presented: (i) perceptual deterioration, (ii) encoding of configural information, and (iii) difficulties in recollecting contextual information. The evidence surveyed provides support for the idea that all three factors are likely to contribute, under certain conditions, to the deficits in face recognition seen in older adults. We discuss how these different factors might interact in the context of a generic framework of the different stages implicated in face recognition. Several suggestions for future investigations are outlined.

When more equals less: overtraining inhibits perceptual learning owing to lack of wakeful consolidation

Performance on perceptual tasks usually improves with training. However, too much consecutive training can be detrimental. Repeated within-day testing or overtraining demonstrates the detrimental effects this has on perceptual learning. Consolidation of learnt information during sleep has the power to prevent such deficits in learning. However, little is known regarding the role of wakeful consolidation in preventing the effects of overtraining. Here, we report that perceptual deterioration may result from the disruption of early wakeful consolidation processes. Three groups were tested on day 1 and again 24 h later, on a motion discrimination task. Participants who had a 1 h break between the two training sessions on the first day displayed improved accuracy on the second day (i.e. learning). Subjects who only completed the first training session on day 1 also exhibited learning. However, individuals who completed two blocks without a break ('overtraining') showed no improvement in accuracy on day 2. Interestingly, changes in reaction times were not susceptible to the effects of overtraining, but instead speeded up as a function of total performed trials. These data suggest that effects of overtraining might be due to disruption of wakeful consolidation processes.

Retrieval-induced Perceptual Suppression: Selective retrieval of mental images can result in perceptual deterioration of non-retrieved images

An attempt to retrieve an item from memory can result in negative effect on future retrieval of other related-but-unwanted items, and such negative consequence of selective retrieval is called ‘Retrieval Induced Forgetting’ (Anderson, Bjork, & Bjork, 1994). The majority of research on retrieval-induced forgetting has employed word recall task to demonstrate the suppression of non-retrieved items on semantic level. The current study suggests that selective retrieval during mental imagery can invoke deterioration of perceptual representation itself. The participants engaged in mental imagery task in which they retrieved the shape of previously studied line-drawing pictures in mind. The category name and the fragmented lines of each picture were presented as retrieval cues. Experiment 1 measured recall accuracy for the picture names to determine whether mental imagery task can invoke retrieval-induced forgetting in verbal dimension. The result showed that recall accuracy for non-retrieved items in retrieved categories (Rp-) was significantly worse than that for non-retrieved categories (Nrp). Experiment 2 employed perceptual identification task in which participant adjusted the level of occluding noise until they were able to identify the original pictures. Noise level for correct identification was lower for Rp- items than Nrp items when measured with the identical pictures presented at the study phase but not with mirror-reversed pictures. This result confirms the decline in identification performance for Rp- items was mainly due to perceptual suppression than to semantic suppression. Experiment 3 employed recognition between a pair of different pictures that have the same name and meaning. The result showed that recognition time for Rp- items was slower than Nrp items. These results suggest that selective retrieval of specific representation during mental imagery can induce forgetting of semantically related-but-unwanted representations in perceptual dimension.

Retrieval-induced perceptual suppression: selective retrieval of mental images can result in perceptual deterioration of non-retrieved images

Retrieval-induced perceptual suppression: selective retrieval of mental images can result in perceptual deterioration of non-retrieved images

Practice little, gain much: Short training enables long-term resistance to perceptual deterioration

Practice little, gain much: Short training enables long-term resistance to perceptual deterioration

Perceptual deterioration predicts performance today

Perceptual deterioration predicts performance today

Explaining training induced performance increments and decrements within a unified framework of perceptual learning

Practicing sensory tasks could result in two main perceptual outcomes. The first, and more widely documented, is perceptual learning referring to long-lasting improvement of perceptual thresholds. The second is perceptual deterioration, which is observed when the number of trials is increased within a training session or between closely spaced sessions. Recent results with visual texture discrimination show that these two processes inversely affect each other: decremental effects interfere with further learning, while efficient short practice results in a long-term learning effect in which performance decrements are practically eliminated. Further results show that sleep is necessary to preserve learning effects following short training and facilitates the decay of deterioration that normally results from extensive training. We suggest a theoretical link between perceptual deterioration and learning, assuming a system with saturating connectivity. Training strengthens task related connections, with further training leading to saturation of these connections along with strengthening of less efficient connections corresponding to accumulated noise in the network. Such saturation in network connectivity and reduction of signal-to-noise ratio consequently affects the readout of the network, causing deterioration in discrimination performance. Thus, best learning is achieved with short training sessions. Resistance to saturation is achieved by sleep-dependent consolidation of unsaturated connectivity. The different transfer properties of the performance decrements and increments allow us to identify local and global components of perceptual learning and their interactions. This suggests sleep-dependent consolidation mechanisms that induce modifications in higher brain areas that interact with local early visual networks to enable improvement of perceptual abilities.

Global resistance to local perceptual adaptation in texture discrimination

Intensive training or testing reduces performance on perceptual tasks. These effects are specific to basic image features, implicating early stages of the visual stream rather than general fatigue. Recent results show that such adaptation-like performance decrements are practically eliminated following practice with a small number of trials and sleep. This long-term learning effect suggests a link between perceptual deterioration and learning at the neuronal connectivity level: training strengthens task related connections, with further training leading to saturation of these connections along with strengthening of less efficient connections corresponding to accumulated noise in the network. Such saturation in network connectivity and reduction of signal-to-noise ratio consequently affects the readout of the network, causing deterioration in discrimination performance. Resistance to such deterioration is achieved by sleep-dependent consolidation of unsaturated connectivity resulting from short training. Here we show that such training-induced resistance to perceptual decrements generalizes across retinal locations, while suppressive effects due to extensive training were shown to be local. Furthermore, we show that these local suppressive effects are long-term, implying consolidation of these effects into what we term as an “adaptational state” in local visual networks. These experiments, revealing the different transfer properties of performance decrements and increments, allow us to identify local and global components of perceptual learning and their interactions, suggesting mechanisms that induce modifications of higher brain areas which interact with local early visual networks and enable improvement of perceptual abilities.

Audition and Cognition: Where Lab Meets Clinic

Audition and Cognition: Where Lab Meets Clinic

Perceptual Deterioration is Reflected in the Neural Response: Fmri Study of Nappers and Non-Nappers

Repeated training on a perceptual task can result in performance deterioration. In the case of vision, this practice-dependent decrease, or perceptual deterioration is restored by changing the target orientation, spatial location, or by taking a daytime nap. Behavioral studies suggest the locus of these performance changes to be primary visual cortex. We used fMRI to directly probe whether perceptual deterioration and nap-dependent maintenance of performance can be detected at the level of primary visual cortex. We also asked whether these changes are due to a bottom-up, stimulus-driven response or a top-down plasticity of attentional mechanisms. Subjects were scanned while performing a texture-discrimination task. Half the subjects took a nap between sessions. We measured the relationship between changes in performance and changes in BOLD signal modulation between the two groups. Non-nappers showed performance deterioration that was significantly correlated with decreased BOLD signal modulation, exclusively in area V1 and limited to the bottom-up condition. In contrast, no change was detected in performance and BOLD response in the two conditions for nappers. These results indicate that napping prevented performance deterioration, which was reflected in the fMRI response of neurons in V1. Without a nap, perceptual deterioration was related to decreases in the stimulus-driven, bottom-up representation, rather than decreases in attentional modulation to the stimulus.

The neural correlates of perceptual learning and deterioration: a role for attention?

The neural correlates of perceptual learning and deterioration: a role for attention?

The time course and specificity of perceptual deterioration.

Repeated within-day testing on a texture discrimination task leads to retinotopically specific decreases in performance. Although perceptual learning has been shown to be highly specific to the retinotopic location and characteristics of the trained stimulus, the specificity of perceptual deterioration has not been studied. We investigated the similarities between learning and deterioration by examining whether deterioration transfers to new distractor or target orientations or to the untrained eye. Participants performed a texture discrimination task in three one-hour sessions. We tested the specificity of deterioration in the final session by switching either the orientation of the background or the target elements by 90 degrees. We found that performance deteriorated steadily both within and across the first two sessions and was specific to the target but not the distractor orientation. In a separate experiment, we found that deterioration transferred to the untrained eye. Changes in performance were independent of reported sleepiness and awareness of stimulus changes, arguing against the possibility that perceptual deterioration is due to general fatigue. Rather, we hypothesize that perceptual deterioration may be caused by changes in the ability for attention to selectively enhance the responses of relatively low-level orientation-selective sensory neurons, possibly within the primary visual cortex. Further, the differences in specificity profiles between learning and deterioration suggest separate underlying mechanisms that occur within the same cortical area.

Perceptual deterioration is specific to background and target orientation.

Perceptual deterioration is specific to background and target orientation.

Recognition of Facial Expressions: Selective Impairment of Specific Emotions in Huntington's Disease

Recognition of facial expressions of basic emotions was investigated in HL and UJ, two people with Huntington's disease who showed little evidence of general cognitive deterioration. No impairments were found in tests of the perception of age, sex, familiar face identity, unfamiliar face identity, and gaze direction, indicating adequate processing of the face as a physical stimulus. Computer-interpolated ("morphed") images of facial expressions of basic emotions were used to demonstrate deficits in the recognition of disgust and fear for UJ. HL also showed a deficit in the recognition of disgust, and was not very adept (but not significantly impaired) at recognising fear. Other basic emotions (happiness, surprise, sadness, anger) were recognised atnormal levels of performance by HL and UJ. These results show that impairments of emotion recognition can be circumscribed; affecting some emotions more than others, and occurring in people who do not show pronounced perceptual or intellectual deterioration. Questionnaires examining self-assessed emotion indicated normal experience of anger by HL and UJ, but possible abnormalities for disgust and fear. The processes involved in recognising other people's emotions may therefore be linked to those involved in experiencing emotion, and the basic emotions of fear and disgust may have separable neural substrates.