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Memory bias in the temporal bisection point.

Levy JM, Namboodiri VM, Hussain Shuler MG - Front Integr Neurosci (2015)

Bottom Line: The ability to time intervals confers organisms, including humans, with many remarkable capabilities.Finally, by using two sets of referent durations, we showed that only memory bias-corrected measures were consistent with a previously reported effect in which the ratio of the referents affects the location of the bisection point.These results suggest that memory effects should be considered in temporal tasks.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, Johns Hopkins University Baltimore, MD, USA.

ABSTRACT
The ability to time intervals confers organisms, including humans, with many remarkable capabilities. A common method for studying interval timing is classification, in which a subject must indicate whether a given probe duration is nearer a previously learned short or long reference interval. This task is designed to reveal the probe duration that is equally likely to be labeled as short or long, known as the temporal bisection point. Studies have found that this bisection point is influenced by a variety of factors including the ratio of the target intervals, the spacing of the probe durations, the modalities of the stimuli, the attentional load, and the inter-trial duration. While several of these factors are thought to be mediated by memory effects, the prototypical classification task affords no opportunity to measure these memory effects directly. Here, we present a novel bisection task, termed the "Bisection by Classification and Production" (BiCaP) task, in which classification trials are interleaved with trials in which subjects must produce either the short or long referents or their midpoint. Using this method, we found a significant correlation between the means of the remembered referents and the bisection points for both classification and production trials. We then cross-validated the bisection points for production and classification trials by showing that they were not statistically differentiable. In addition to these population-level effects, we found within-subject evidence for co-variation across a session between the production bisection points and the means of the remembered referents. Finally, by using two sets of referent durations, we showed that only memory bias-corrected measures were consistent with a previously reported effect in which the ratio of the referents affects the location of the bisection point. These results suggest that memory effects should be considered in temporal tasks.

No MeSH data available.


Memory bias in production and classification. (A) We found a statistically significant correlation between the bias-corrected AM and the classification bisection point (p = 0.022) assuming a movement time 0 ms (left panel). We also found a highly significant correlation (p = 1.9 × 10-7) with the bias-corrected AM for the production bisection point (right panel). (B) These results do not change assuming a different movement time (i.e., 175 ms). Production bisection points were not statistically distinguishable from classification bisection points (C) if movement time was assumed to be zero (p = 0.15, two-tailed Mann–Whitney U-test, U18 = 356, z = -1.45) or (D) if movement time was assumed to be 175 ms (p = 0.64, U18 = 392, z = -0.47).
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Figure 2: Memory bias in production and classification. (A) We found a statistically significant correlation between the bias-corrected AM and the classification bisection point (p = 0.022) assuming a movement time 0 ms (left panel). We also found a highly significant correlation (p = 1.9 × 10-7) with the bias-corrected AM for the production bisection point (right panel). (B) These results do not change assuming a different movement time (i.e., 175 ms). Production bisection points were not statistically distinguishable from classification bisection points (C) if movement time was assumed to be zero (p = 0.15, two-tailed Mann–Whitney U-test, U18 = 356, z = -1.45) or (D) if movement time was assumed to be 175 ms (p = 0.64, U18 = 392, z = -0.47).

Mentions: Next, we sought to assess the degree to which memory biases may have affected the location of the bisection point on both classification and production trials. To this end, we examined the correlation between the bias-corrected mean and the bisection points across subjects for classification trials (p = 0.022, R2 = 0.26) and production trials (p = 1.9 × 10-7, R2 = 0.79) and found both to be significant (Figure 2A, top). (Separating by groups, we found: classification 1/5 s: p = 0.175, R2 = 0.22; production 1/5 s: p = 0.002, R2 = 0.70; classification 2/4 s: p = 0.098, R2 = 0.30, production 2/4 s: p = 3.14 × 10-5, R2 = 0.90.) We examined the co-variation between classification and production bisection points (Figure 2C) and also found no significant difference between these groups (p = 0.15, two-tailed Mann–Whitney U-test, U18 = 356, z = -1.45).


Memory bias in the temporal bisection point.

Levy JM, Namboodiri VM, Hussain Shuler MG - Front Integr Neurosci (2015)

Memory bias in production and classification. (A) We found a statistically significant correlation between the bias-corrected AM and the classification bisection point (p = 0.022) assuming a movement time 0 ms (left panel). We also found a highly significant correlation (p = 1.9 × 10-7) with the bias-corrected AM for the production bisection point (right panel). (B) These results do not change assuming a different movement time (i.e., 175 ms). Production bisection points were not statistically distinguishable from classification bisection points (C) if movement time was assumed to be zero (p = 0.15, two-tailed Mann–Whitney U-test, U18 = 356, z = -1.45) or (D) if movement time was assumed to be 175 ms (p = 0.64, U18 = 392, z = -0.47).
© Copyright Policy
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4493391&req=5

Figure 2: Memory bias in production and classification. (A) We found a statistically significant correlation between the bias-corrected AM and the classification bisection point (p = 0.022) assuming a movement time 0 ms (left panel). We also found a highly significant correlation (p = 1.9 × 10-7) with the bias-corrected AM for the production bisection point (right panel). (B) These results do not change assuming a different movement time (i.e., 175 ms). Production bisection points were not statistically distinguishable from classification bisection points (C) if movement time was assumed to be zero (p = 0.15, two-tailed Mann–Whitney U-test, U18 = 356, z = -1.45) or (D) if movement time was assumed to be 175 ms (p = 0.64, U18 = 392, z = -0.47).
Mentions: Next, we sought to assess the degree to which memory biases may have affected the location of the bisection point on both classification and production trials. To this end, we examined the correlation between the bias-corrected mean and the bisection points across subjects for classification trials (p = 0.022, R2 = 0.26) and production trials (p = 1.9 × 10-7, R2 = 0.79) and found both to be significant (Figure 2A, top). (Separating by groups, we found: classification 1/5 s: p = 0.175, R2 = 0.22; production 1/5 s: p = 0.002, R2 = 0.70; classification 2/4 s: p = 0.098, R2 = 0.30, production 2/4 s: p = 3.14 × 10-5, R2 = 0.90.) We examined the co-variation between classification and production bisection points (Figure 2C) and also found no significant difference between these groups (p = 0.15, two-tailed Mann–Whitney U-test, U18 = 356, z = -1.45).

Bottom Line: The ability to time intervals confers organisms, including humans, with many remarkable capabilities.Finally, by using two sets of referent durations, we showed that only memory bias-corrected measures were consistent with a previously reported effect in which the ratio of the referents affects the location of the bisection point.These results suggest that memory effects should be considered in temporal tasks.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, Johns Hopkins University Baltimore, MD, USA.

ABSTRACT
The ability to time intervals confers organisms, including humans, with many remarkable capabilities. A common method for studying interval timing is classification, in which a subject must indicate whether a given probe duration is nearer a previously learned short or long reference interval. This task is designed to reveal the probe duration that is equally likely to be labeled as short or long, known as the temporal bisection point. Studies have found that this bisection point is influenced by a variety of factors including the ratio of the target intervals, the spacing of the probe durations, the modalities of the stimuli, the attentional load, and the inter-trial duration. While several of these factors are thought to be mediated by memory effects, the prototypical classification task affords no opportunity to measure these memory effects directly. Here, we present a novel bisection task, termed the "Bisection by Classification and Production" (BiCaP) task, in which classification trials are interleaved with trials in which subjects must produce either the short or long referents or their midpoint. Using this method, we found a significant correlation between the means of the remembered referents and the bisection points for both classification and production trials. We then cross-validated the bisection points for production and classification trials by showing that they were not statistically differentiable. In addition to these population-level effects, we found within-subject evidence for co-variation across a session between the production bisection points and the means of the remembered referents. Finally, by using two sets of referent durations, we showed that only memory bias-corrected measures were consistent with a previously reported effect in which the ratio of the referents affects the location of the bisection point. These results suggest that memory effects should be considered in temporal tasks.

No MeSH data available.