Adaptation aftereffects are the tendency to perceive an ambiguous target stimulus, which follows an adaptor stimulus, as different from the adaptor. A duration dependence of face adaptation aftereffects has been demonstrated for durations... more
Adaptation aftereffects are the tendency to perceive an ambiguous target stimulus, which follows an adaptor stimulus, as different from the adaptor. A duration dependence of face adaptation aftereffects has been demonstrated for durations of at least 500ms, for identity related judgments. Here we describe the duration dependence of the adaptation af-tereffects of very brief (11.7ms-500ms) backwardly masked faces, on both expression and identity category judgments of ambiguous target faces. We find significant aftereffects at minimum duration 23.5ms for emotional expression, and 47ms for identity, but these are abolished by backward masking with an inverted face, although these same adaptors can be correctly categorized above chance. The presence of a short duration adaptation effect in expression might be mediated by rapid transfer of low spatial frequency (LSF) information. We tested this possibility by comparing aftereffects in low pass and high pass filtered ambiguous targets, and found no evidence of independent adaptation of a LSF specific channel.
Research Interests:
Recent demonstrations of the anticonvulsant properties of agmatine suggest it may be considered as a potential adjunct for protection against seizure. We investigated the possibility of an additive anticonvulsant effect between low doses... more
Recent demonstrations of the anticonvulsant properties of agmatine suggest it may be considered as a potential adjunct for protection against seizure. We investigated the possibility of an additive anticonvulsant effect between low doses of agmatine and morphine. The thresholds for the clonic seizures induced by the intravenous administration of gamma-aminobutyric acid (GABA)-antagonist, pentylenetetrazole (PTZ) were assessed in mice. Morphine at lower doses (1–3 mg/kg) increased and at higher doses (30, 60 mg/kg) decreased the seizure threhsold. Pretreatment with a per se non-effective dose of agmatine (1 mg/kg) potentiated the anticonvulsant effect of morphine. The combination of subeffective doses of agmatine and morphine led to potent anticonvulsant effects. The proconvulsant effect of morphine was attenuated by agmatine. Yohimbine with a dose (1 mg/kg) incapable of affecting seizure threshold reversed the effect of agmatine on both anticonvulsant and proconvulsant effects of morphine. These results suggest that agmatine potentiates the anticonvulsant effect of morphine and alpha 2-adrenoceptors may be involved in this effect.
Research Interests:
A brief target embedded in—and coterminating with—a noise mask is identified easily when the duration of the mask is long but not when it is short (Di Lollo, 1980; inverse-duration effect). Identification has been said to be mediated by... more
A brief target embedded in—and coterminating with—a noise mask is identified easily when the duration
of the mask is long but not when it is short (Di Lollo, 1980; inverse-duration effect). Identification has
been said to be mediated by the visible persistence of the target, which outlasted that of the mask. We
tested an alternative account based on input filtering triggered by the onset and offset of the target,
relative to those of the mask, without recourse to visible persistence. The results of Experiment 1 could
not be explained wholly in terms of visible persistence but were entirely consistent with input filtering.
Identification suffered in Experiment 2 when transient responses were attenuated by “ramping.” In
Experiment 3, accuracy improved gradually as a function of leading-mask duration. All results were
consistent with a modified version of von Holst’s (1954) hypothesis that a new stimulus (e.g., the present
mask) establishes an input filter within the system. Any sudden onsets or offsets then lead to the
perception of a new object only when they do not match the input filter, thus becoming segregated from
the temporally leading stimulus.
of the mask is long but not when it is short (Di Lollo, 1980; inverse-duration effect). Identification has
been said to be mediated by the visible persistence of the target, which outlasted that of the mask. We
tested an alternative account based on input filtering triggered by the onset and offset of the target,
relative to those of the mask, without recourse to visible persistence. The results of Experiment 1 could
not be explained wholly in terms of visible persistence but were entirely consistent with input filtering.
Identification suffered in Experiment 2 when transient responses were attenuated by “ramping.” In
Experiment 3, accuracy improved gradually as a function of leading-mask duration. All results were
consistent with a modified version of von Holst’s (1954) hypothesis that a new stimulus (e.g., the present
mask) establishes an input filter within the system. Any sudden onsets or offsets then lead to the
perception of a new object only when they do not match the input filter, thus becoming segregated from
the temporally leading stimulus.
Research Interests:
We report a new mutation in the APP gene. This mutation, like several others (go to http://molgen-www.uia.ac.be/ADMutations5 for more information) clusters just outside the C-terminal of the A sequence and is likely to alter APP... more
We report a new mutation in the APP gene. This
mutation, like several others (go to http://molgen-www.uia.ac.be/ADMutations5 for more information) clusters just outside the C-terminal of the A sequence and is likely to alter APP processing such that more A42 is produced.6 The age at onset of the disease in this family is considerably older than that caused by the other mutation at this site4 (T714I), presumably because alanine causes less disruption to the transmembrane structure of APP than isoleucine. This mutation is the eighth in the cluster just outside the A42 sequence and confirms that mutations at any residue from codon 714 to codon 717 (one helical turn) can disrupt APP processing such that more A42 is (presumably) produced. In the tradition of naming mutations (for examples to go http://molgen-www.uia.ac.be/ADMutations), we suggest naming this mutation the Iranian mutation.
mutation, like several others (go to http://molgen-www.uia.ac.be/ADMutations5 for more information) clusters just outside the C-terminal of the A sequence and is likely to alter APP processing such that more A42 is produced.6 The age at onset of the disease in this family is considerably older than that caused by the other mutation at this site4 (T714I), presumably because alanine causes less disruption to the transmembrane structure of APP than isoleucine. This mutation is the eighth in the cluster just outside the A42 sequence and confirms that mutations at any residue from codon 714 to codon 717 (one helical turn) can disrupt APP processing such that more A42 is (presumably) produced. In the tradition of naming mutations (for examples to go http://molgen-www.uia.ac.be/ADMutations), we suggest naming this mutation the Iranian mutation.
Research Interests:
Communicated by Mark H. Paalman As Human Genome Project exploration continues, the necessity of having a broader spectrum of genomic DNA material from different nationalities to study various aspects of hereditary disease becomes more... more
Communicated by Mark H. Paalman As Human Genome Project exploration continues, the necessity of having a broader spectrum of genomic DNA material from different nationalities to study various aspects of hereditary disease becomes more obvious. The existence of high genetic polymorphism within and between different communities in the world makes it necessary for the gene hunters to investigate many different populations. Iran, a large country with close to 66 million people, is a land of different nationalities, tribes, and religions that offers a highly heterogeneous gene pool to the genetics researcher. The purity of many different races in this country has been highly conserved by geographical borders and by an ancient culture that has always encouraged intrafamilial marriages. All these have created a population that is remarkably heterogeneous yet high in consanguinity rate. During the last five years of investigation we have established a DNA bank, the Iranian Human Mutation Gene Bank (www.IHMGB.com), which contains all genetic diseases studied in Iran that have the Mendelian mode of inheritance. Some of the samples are assigned to common or novel mutations and others belong to patients with clinical profiles associated with particular genetic diseases but undefined mutation. This bank stores samples of DNA from the patient and his/her first-degree relatives together with a comprehensive pedigree and clinical profile for each sample. To facilitate collaboration with other scientists around the world with the same interests, we decided to present our experimental projects online. This DNA bank provides opportunities for us to collaborate with scientists outside Iran. It offers a sample resource to research scientists around the world, at no charge, for the purpose of investigating the various aspects of genetic disorders from prenatal diagnosis to gene structure and function. It is strongly stressed that no commercial benefit is involved in the establishment of this DNA bank and the DNA samples are free of charge. However, to meet our goals and to respect ethical values, DNA samples can only be used under certain conditions stated in the User Consent Form. Hum Mutat 21:146–150
Research Interests:
The presence of a salient distractor interferes with visual search. According to the salience-driven selection hypothesis, this interference is because of an initial deployment of attention to the distractor. Three event-related potential... more
The presence of a salient distractor interferes with visual search. According to the salience-driven
selection hypothesis, this interference is because of an initial deployment of attention to the distractor.
Three event-related potential (ERP) findings have been regarded as evidence for this hypothesis: (a)
salient distractors were found to elicit an ERP component called N2pc, which reflects attentional
selection; (b) with target and distractor on opposite sides, a distractor N2pc was reported to precede the target N2pc (N2pc flip); (c) the distractor N2pc on slow-response trials was reported to occur particularly early, suggesting that the fastest shifts of attention were driven by salience. This evidence is equivocal, however, because the ERPs were noisy (b, c) and were averaged across all trials, thereby making it difficult to know whether attention was deployed directly to the target on some trials (a, b). We reevaluated this evidence using a larger sample size to reduce noise and by analyzing ERPs separately for fast- and slow-response trials. On fast-response trials, the distractor elicited a contralateral positivity (PD)—an index of attentional suppression—instead of an N2pc. There was no N2pc flip or early distractor N2pc. As it stands, then, there is no ERP evidence for the salience-driven selection hypothesis.
selection hypothesis, this interference is because of an initial deployment of attention to the distractor.
Three event-related potential (ERP) findings have been regarded as evidence for this hypothesis: (a)
salient distractors were found to elicit an ERP component called N2pc, which reflects attentional
selection; (b) with target and distractor on opposite sides, a distractor N2pc was reported to precede the target N2pc (N2pc flip); (c) the distractor N2pc on slow-response trials was reported to occur particularly early, suggesting that the fastest shifts of attention were driven by salience. This evidence is equivocal, however, because the ERPs were noisy (b, c) and were averaged across all trials, thereby making it difficult to know whether attention was deployed directly to the target on some trials (a, b). We reevaluated this evidence using a larger sample size to reduce noise and by analyzing ERPs separately for fast- and slow-response trials. On fast-response trials, the distractor elicited a contralateral positivity (PD)—an index of attentional suppression—instead of an N2pc. There was no N2pc flip or early distractor N2pc. As it stands, then, there is no ERP evidence for the salience-driven selection hypothesis.
Research Interests:
Identification of the second of two targets (T2) is impaired when presented shortly after the first (T1). T1-based theories ascribe this attentional blink (AB) to a T1-initiated period of inattention. Distractor-based theories ascribe it... more
Identification of the second of two targets (T2) is
impaired when presented shortly after the first (T1). T1-based
theories ascribe this attentional blink (AB) to a T1-initiated
period of inattention. Distractor-based theories ascribe it to a
disruption of input control caused by post-T1 distractors. The
finding that an AB occurs without intertarget distractors
(Nieuwenstein, Potter, & Theeuwes, Journal of Experimental
Psychology: Human Perception and Performance 35:159-169,
2009) seemingly disconfirms distractor-based theories. The
present experiments addressed different ways in which
distractor-based theories might account for that finding.
Intertarget events were varied in four experiments. Experiment
1 replicated Nieuwenstein, Potter, and Theeuwes’s findings. The
next two experiments tested two ways (lack of visual stimulation,
violation of expectation) in which the blank intertarget
interval might cause an AB. Experiment 4 explored whether
backward-masking of T1 can account entirely for the larger AB
obtained with intervening distractors or whether distractors also disrupt input control. The results disconfirm predictions from distractor-based theories and support the claim of T1-based theories that T1 processing alone is sufficient for the AB.
Simulations based on the eSTST (Wyble, Bowman, &
Nieuwenstein, Journal of Experimental Psychology: Human
Perception and Performance 35:787-807, 2009) and the B&B
models (Olivers & Meeter, Psychological Research, 115, 836-
863 2008) were compared. Predictions were more accurate from the T1-based theory (eSTST) than from the distractor-based theory (B&B).
impaired when presented shortly after the first (T1). T1-based
theories ascribe this attentional blink (AB) to a T1-initiated
period of inattention. Distractor-based theories ascribe it to a
disruption of input control caused by post-T1 distractors. The
finding that an AB occurs without intertarget distractors
(Nieuwenstein, Potter, & Theeuwes, Journal of Experimental
Psychology: Human Perception and Performance 35:159-169,
2009) seemingly disconfirms distractor-based theories. The
present experiments addressed different ways in which
distractor-based theories might account for that finding.
Intertarget events were varied in four experiments. Experiment
1 replicated Nieuwenstein, Potter, and Theeuwes’s findings. The
next two experiments tested two ways (lack of visual stimulation,
violation of expectation) in which the blank intertarget
interval might cause an AB. Experiment 4 explored whether
backward-masking of T1 can account entirely for the larger AB
obtained with intervening distractors or whether distractors also disrupt input control. The results disconfirm predictions from distractor-based theories and support the claim of T1-based theories that T1 processing alone is sufficient for the AB.
Simulations based on the eSTST (Wyble, Bowman, &
Nieuwenstein, Journal of Experimental Psychology: Human
Perception and Performance 35:787-807, 2009) and the B&B
models (Olivers & Meeter, Psychological Research, 115, 836-
863 2008) were compared. Predictions were more accurate from the T1-based theory (eSTST) than from the distractor-based theory (B&B).
Research Interests:
Identification of the second of two targets (T2) is impaired when presented shortly after the first (T1). This attentional blink (AB) is thought to arise from a delay in T2 processing during which T2 is vulnerable to masking. Conventional... more
Identification of the second of two targets (T2) is impaired when presented shortly after the first (T1). This attentional blink (AB) is thought to arise from a delay in T2 processing during which T2 is vulnerable to masking. Conventional studies have measured T2 accuracy which is constrained by the 100% ceiling. We avoided this problem by using a dynamic threshold-tracking procedure that is inherently free from ceiling constraints. In two experiments we examined how AB magnitude is affected by three masking-related factors: (a) presence/absence of T2 mask, (b) T2-mask stimulus onset asyn-chrony (SOA), and (c) level of T2 impoverishment (signal-to-noise ratio [SNR]). In Experiment 1, overall accuracy decreased with T2-mask SOA. The magnitude of the AB, however, was invariant with SOA and with mask presence/absence. Experiment 2 further showed that the AB was invariant with T2 SNR. The relationship among mask presence/absence, SOA, and T2 SNR and the AB is encompassed in a qualitative model.
Research Interests:
Report of a second target (T2) is impaired when presented within 500 ms of the first (T1). This attentional blink (AB) is known to cause a delay in T2 processing during which T2 must be stored in a labile memory buffer. We explored the... more
Report of a second target (T2) is impaired when presented within 500 ms of the first (T1). This attentional blink (AB) is known to cause a delay in T2 processing during which T2 must be stored in a labile memory buffer. We explored the buffer's characteristics using different types of masks after T2. These characteristics were inferred by determining what attributes of T2 are hindered by a given form of masking. In Experiments 1–3, trailing metacontrast and four-dot masks produced ABs of equal magnitudes, implicating the onset-transient triggered by the mask as the mechanism underlying the AB and strongly suggesting a locus in early vision. In Experiment 4, metacontrast and four-dot masks were presented in a common-onset masking (COM) paradigm in which a brief, combined display of T2 and the mask was followed by a longer display of the mask alone. COM is thought to occur late in the sequence of processing events. No AB occurred with COM, confirming the critical role of the mask's onset transients and ruling out a high-level locus for the labile memory buffer.
Research Interests:
Identification of the second of two targets (T1, T2, inserted in a stream of distractors) is impaired when presented within 500 ms after the first (attentional blink, AB). Barring a T1-T2 task-switch, it is thought that T2 must be... more
Identification of the second of two targets (T1, T2, inserted in a stream of distractors) is impaired when presented within 500 ms after the first (attentional blink, AB). Barring a T1-T2 task-switch, it is thought that T2 must be backward-masked to obtain an AB (Giesbrecht & Di Lollo, Journal of Experimental Psychology: Human Perception and Performance, 24, 1454-1466, 1998). We tested the hypothesis that Giesbrecht & Di Lollo's findings were vitiated by ceiling constraints arising from either response scale (experiment 1) or data limitations (experiment 2). In experiment 1, digit-distractors were replaced with pseudoletters to increase task difficulty, bringing performance below ceiling. An AB occurred without backward masking of T2. In experiment 2, a ceiling-free procedure estimated the number of noise dots needed for 80% T2 identification. An AB was revealed: fewer noise dots were required during the AB period than outside it. Both outcomes confirm that an AB can be obtained without either masking of T2 or task switching.
Research Interests:
Salient distractors delay visual search for less salient targets in additional-singleton tasks, even when the features of the stimuli are fixed across trials. According to the salience-driven selection hypothesis, this delay is due to an... more
Salient distractors delay visual search for less salient targets in additional-singleton tasks, even when the features of the stimuli are fixed across trials. According to the salience-driven selection hypothesis, this delay is due to an initial attentional deployment to the distractor. Recent event-related potential (ERP) studies found no evidence for salience-driven selection in fixed-feature search, but the methods employed were not optimized to isolate distractor ERP components such as the N2pc and distractor positivity (P D ; indices of selection and suppression, respectively). Here, we isolated target and distractor ERPs in two fixed-feature search experiments. Participants searched for a shape singleton in the presence of a more-salient color singleton (Experiment 1) or for a color singleton in the presence of a less-salient shape singleton (Experiment 2). The salient distractor did not elicit an N2pc, but it did elicit a P D on fast-response trials. Furthermore, distractors had no effect on the timing of the target N2pc. These results indicate that (a) the distractor was prevented from engaging the attentional mechanism associated with N2pc, (b) the distractor did not interrupt the deployment of attention to the target, and (c) competition for attention can be resolved by suppressing locations of irrelevant items on a salience-based priority map.
Research Interests:
Research Interests:
Research Interests:
Relative blindsight is said to occur when different levels of subjective awareness are obtained at equality of objective performance. Using metacontrast masking, Lau and Passingham (2006) reported relative blindsight in normal observers... more
Relative blindsight is said to occur when different levels of subjective awareness are obtained at equality of objective performance. Using metacontrast masking, Lau and Passingham (2006) reported relative blindsight in normal observers at the shorter of two stimulus-onset asynchronies (SOAs) between target and mask. Experiment 1 replicated the critical asymmetry in subjective awareness at equality of objective performance. We argue that this asymmetry cannot be regarded as evidence for relative blindsight because the observers' responses were based on different attributes of the stimuli (criterion contents) at the two SOAs. With an invariant criterion content (Experiment 2), there was no asymmetry in subjective awareness across the two SOAs even though objective performance was the same. Experiment 3 examined the effect of criterion level on estimates of relative blindsight. Collectively, the present results question whether metacontrast masking is a suitable paradigm for establishing relative blindsight. Implications for theories of consciousness are discussed.
Research Interests:
Objectives: This study was conducted to evaluate the effect of simvastatin (40 mg/day) as an adjuvant therapy to interferon beta (IFNb 1a, 30 mg once weekly) in relapsing–remitting multiple sclerosis patients, compared with placebo.... more
Objectives: This study was conducted to evaluate the effect of simvastatin (40 mg/day) as an adjuvant therapy to interferon beta (IFNb 1a, 30 mg once weekly) in relapsing–remitting multiple sclerosis patients, compared with placebo. Methods: We enrolled 85 patients with relapsing–remitting multiple sclerosis (71% female) who were already receiving IFNb 1a (Avonex), with Expanded Disability Status Scale score of less than 5.0. The patients were assigned (in random and double-blinded fashion) into the two groups of simvastatin and placebo. All patients continued to receive their current IFNb treatment. The outcome measures were total relapse rate, Expanded Disability Status Scale score, and the number of gadolinium-enhanced (Gdþ) and new T2 lesions in magnetic resonance imaging after a 1-year follow-up. We used Mann–Whitney and one-way multivariate analysis of variances to analyze the data. Results: Four patients in the placebo and two in the simvastatin group prematurely withdrew from the study due to experiencing two attacks. The total attack number in the simvastatin group was significantly lower than placebo group (moderate effect size r ¼ 0.29) (p ¼ 0.01). The final Expanded Disability Status Scale scores were lower in the simvastatin group (1.01 AE 1.40, mean AE SD) than in the placebo group (1.73 AE 1.49, mean AE SD), but this difference was not significant after controlling the baseline Expanded Disability Status Scale score (p ¼ 0.07). In the simvastatin group, the mean AE SD of gadolinium-enhanced and new T2 lesions were 0.66 AE 1.18 and 3.39 AE 3.55, respectively, (compared with 0.74 AE 1.21 and 3.39 AE 3.55 in the placebo group). Although there was a decreasing trend in lesions on magnetic resonance imaging, this difference was not statistically significant (p ¼ 0.62). The combination therapy was safe and well tolerated, and no serious adverse effect was noted. Conclusion: Our study supports the safety and efficacy of simvastatin as an add-on therapy to INFb 1a in patients with relapsing–remitting multiple sclerosis. TRIAL REGISTRATION: ClinicalTrials.gov NCT00668343. This interventional study provides Class I evidence stating that adding simvastatin 40 mg/day to IFNb 1a 30 mg a week in patients with relapsing–remitting multiple sclerosis may reduce the relapse rate (moderate effect size r ¼ 0.29) (p ¼ 0.01) compared with treatment with IFNb 1a alone.
Research Interests:
Research Interests:
Research Interests:
The capacity of visual short-term memory (VSTM) is commonly estimated by K scores obtained with a change-detection task. Contrary to common belief, K may be influenced not only by capacity but also by the rate at which stimuli are encoded... more
The capacity of visual short-term memory (VSTM) is commonly estimated by K scores obtained with a change-detection task. Contrary to common belief, K may be influenced not only by capacity but also by the rate at which stimuli are encoded into VSTM. Experiment 1 showed that, contrary to earlier conclusions, estimates of VSTM capacity obtained with a change-detection task are constrained by temporal limitations. In Experiment 2, we used change-detection and backward-masking tasks to obtain separate within-subject estimates of K and of rate of encoding, respectively. A median split based on rate of encoding revealed significantly higher K estimates for fast encoders. Moreover, a significant correlation was found between K and the estimated rate of encoding. The present findings raise the prospect that the reported relationships between K and such cognitive concepts as fluid intelligence may be mediated not only by VSTM capacity but also by rate of encoding. (PsycINFO Database Record
Research Interests:
Research Interests:
We report a new mutation in the APP gene. This mutation, like several others (go to http://molgen-www.uia.ac.be/ADMutations5 for more information) clusters just outside the C-terminal of the A sequence and is likely to alter APP... more
We report a new mutation in the APP gene. This mutation, like several others (go to http://molgen-www.uia.ac.be/ADMutations5 for more information) clusters just outside the C-terminal of the A sequence and is likely to alter APP processing such that more A42 is produced.6 The age at onset of the disease in this family is considerably older than that caused by the other mutation at this site4 (T714I), presumably because alanine causes less disruption to the transmembrane structure of APP than isoleucine. This mutation is the eighth in the cluster just outside the A42 sequence and confirms that mutations at any residue from codon 714 to codon 717 (one helical turn) can disrupt APP processing such that more A42 is (presumably) produced. In the tradition of naming mutations (for examples to go http://molgen-www.uia.ac.be/ADMutations), we suggest naming this mutation the Iranian mutation.
Research Interests:
Research Interests:
Report of a second target (T2) is impaired when presented within 500 ms of the first (T1). This attentional blink (AB) is known to cause a delay in T2 processing during which T2 must be stored in a labile memory buffer. We explored the... more
Report of a second target (T2) is impaired when presented within 500 ms of the first (T1). This attentional blink (AB) is known to cause a delay in T2 processing during which T2 must be stored in a labile memory buffer. We explored the buffer's characteristics using different types of masks after T2. These characteristics were inferred by determining what attributes of T2 are hindered by a given form of masking. In Experiments 1-3, trailing metacontrast and four-dot masks produced ABs of equal magnitudes, implicating the onset-transient triggered by the mask as the mechanism underlying the AB and strongly suggesting a locus in early vision. In Experiment 4, metacontrast and four-dot masks were presented in a common-onset masking (COM) paradigm in which a brief, combined display of T2 and the mask was followed by a longer display of the mask alone. COM is thought to occur late in the sequence of processing events. No AB occurred with COM, confirming the critical role of the mask's onset transients and ruling out a high-level locus for the labile memory buffer.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Relative blindsight is said to occur when different levels of subjective awareness are obtained at equality of objective performance. Using metacontrast masking, Lau and Passingham (2006) reported relative blindsight in normal observers... more
Relative blindsight is said to occur when different levels of subjective awareness are obtained at equality of objective performance. Using metacontrast masking, Lau and Passingham (2006) reported relative blindsight in normal observers at the shorter of two stimulus-onset asynchronies (SOAs) between target and mask. Experiment 1 replicated the critical asymmetry in subjective awareness at equality of objective performance. We argue that this asymmetry cannot be regarded as evidence for relative blindsight because the observers' responses were based on different attributes of the stimuli (criterion contents) at the two SOAs. With an invariant criterion content (Experiment 2), there was no asymmetry in subjective awareness across the two SOAs even though objective performance was the same. Experiment 3 examined the effect of criterion level on estimates of relative blindsight. Collectively, the present results question whether metacontrast masking is a suitable paradigm for establishing relative blindsight. Implications for theories of consciousness are discussed.