Effects of rise/fall time on masked detection thresholds and temporal integration for noise band signals

1994 ◽  
Vol 96 (5) ◽  
pp. 3257-3258
Author(s):  
M. G. Heinz ◽  
C. Formby ◽  
K. L. Mortimer
Keyword(s):  
Temporal Integration ◽  
Noise Band ◽  
Detection Thresholds ◽  
Fall Time ◽  
Masked Detection

Masked detection thresholds and temporal integration for noise band signals

1994 ◽  
Vol 96 (1) ◽  
pp. 102-114 ◽  
Author(s):  
C. Formby ◽  
M. G. Heinz ◽  
C. E. Luna ◽  
M. K. Shaheen
Keyword(s):  
Temporal Integration ◽  
Noise Band ◽  
Detection Thresholds ◽  
Masked Detection

Temporal Integration and the Masking Effect of Spatiotemporal Noise

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 216-216 ◽  
Author(s):  
H T Kukkonen ◽  
J Rovamo
Keyword(s):  
Spectral Density ◽  
Exposure Duration ◽  
Temporal Integration ◽  
Detection Threshold ◽  
Critical Duration ◽  
Masking Effect ◽  
Integration Time ◽  
Detection Thresholds ◽  
Spatial Noise ◽  
Spatiotemporal Noise

In computer-generated spatiotemporal noise every stimulus frame contains a new static noise sample. The spectral density of white spatiotemporal noise is calculated by multiplying the squared rms contrast of noise by the product of the noise check area and the exposure duration of each noise check. When the exposure duration of each noise check is gradually increased, the spectral density of spatiotemporal noise increases, reaching its maximum when noise becomes static. In static spatial noise both stimulus and noise checks have the same duration. The signal-to-noise ratio is known to be constant at detection threshold. Detection thresholds should thus increase in proportion to the spectral density of spatiotemporal noise, which increases with the duration of the noise checks. We measured detection thresholds for stationary cosine gratings embedded in spatiotemporal noise. The exposure duration of the noise checks was increased from one frame duration to the total exposure duration of the stimulus grating. Noise was thus gradually transformed from spatiotemporal to static spatial noise. The contrast energy threshold increased in proportion to the spectral density of spatiotemporal noise up to a noise check duration found to be equal to the integration time for the stimulus grating without noise. After this, energy thresholds remained constant in spite of the increase in the spectral density of spatiotemporal noise. This suggests that the masking effect of spatiotemporal noise increases with the duration of noise checks up to the critical duration marking the saturation of the temporal integration of the signal.

Temporal integration of noise band signals measured in a profile analysis task

1992 ◽  
Vol 92 (4) ◽  
pp. 2317-2317
Author(s):  
C. Formby ◽  
M. G. Heinz ◽  
C. E. Luna ◽  
S. C. Elbert
Keyword(s):  
Profile Analysis ◽  
Temporal Integration ◽  
Noise Band ◽  
Analysis Task

Temporal Integration of Sinusoidal Increments in the Absence of Absolute Energy Cues

2002 ◽  
Vol 45 (6) ◽  
pp. 1285-1296 ◽  
Author(s):  
C. Formby ◽  
M. G. Heinz ◽  
I. V. Aleksandrovsky
Keyword(s):  
Frequency Dependence ◽  
Temporal Integration ◽  
Frequency Selectivity ◽  
Integration Process ◽  
Frequency Range ◽  
Detection Thresholds ◽  
Absolute Energy ◽  
Per Se ◽  
Process Detection ◽  
Random Level

Classical temporal integration (TI) is often viewed as a frequency-dependent, energy-based detection process. Detection thresholds for brief sinusoidal increments in either a fixed-level or a random-level broadband pedestal are reported that refute this traditional perspective of TI. Instead, evidence is presented that indicates (a) detection of absolute energy is not necessary for the TI effect and (b) the frequency dependence of TI is consistent with variations across frequency in peripheral auditory tuning, rather than the integration process per se. When peripheral frequency selectivity is controlled, TI can be explained by a frequencyinvariant integration process over at least the frequency range from 500 to 4000 Hz. This process is characterized by threshold improvements of 8–9 dB per decade increase in duration for increment durations between 10 and 300 ms.

scholarly journals Temporal integration for amplitude modulation in childhood: Interaction between internal noise and memory factors

2021 ◽  
Author(s):  
Laurianne Cabrera ◽  
Irene Lorenzini ◽  
Stuart Rosen ◽  
léo varnet ◽  
Lorenzi Christian
Keyword(s):  
Amplitude Modulation ◽  
Short Term Memory ◽  
Temporal Integration ◽  
Age Groups ◽  
Computational Modelling ◽  
Internal Noise ◽  
Older Children ◽  
Processing Efficiency ◽  
Detection Thresholds ◽  
Gradual Improvement

It is still unclear whether the gradual improvement in amplitude-modulation (AM) sensitivity typically found in children up to 10 years of age reflects an improvement in “processing efficiency” (the central ability to use information extracted by sensory mechanisms). This hypothesis was tested by evaluating temporal integration for AM, a capacity relying on memory and decision factors. This was achieved by measuring the effect of increasing the number of AM cycles (2 vs 8) on AM-detection thresholds for three groups of children aged from 5 to 11 years and a group of young adults. AM- detection thresholds were measured using a forced-choice procedure and sinusoidal AM (4 or 32 Hz rate) applied to a 1024-Hz pure-tone carrier. All age groups demonstrated temporal integration for AM at both rates, that is significant improvements in AM sensitivity with a higher number of AM cycles. However, both 5- 6 years and adults exhibited similar levels of temporal integration, while 7-8 and 10- 11 years showed less integration. This is because at both rates: (i) the youngest group (5-6 years) displayed the worst thresholds with 2 AM cycles but similar thresholds with 8 cycles compared to older children groups, and (ii) adults showed the best thresholds with 8 AM cycles but similar thresholds with 2 cycles compared to older children groups. Computational modelling indicated that higher levels of internal noise combined with poorer short-term memory capacities in children accounted for the developmental trends. Improvement in processing efficiency may therefore account for the development of AM detection in childhood.

Influence of motion on chromatic detection

2004 ◽  
Vol 21 (3) ◽  
pp. 327-330 ◽  
Author(s):  
PATRICK MONNIER ◽  
STEVEN K. SHEVELL
Keyword(s):  
Temporal Integration ◽  
Neural Mechanism ◽  
Circular Path ◽  
Spatial Integration ◽  
Random Condition ◽  
Threshold Elevation ◽  
Detection Thresholds ◽  
Presentation Sequence ◽  
Coherent Condition ◽  
Spatiotemporal Integration

Intense scrutiny has been focused on whether chromatic stimuli contribute to motion perception. The present study considers a related but different question: how does motion affect chromatic detection? Detection thresholds were measured for a disk that underwent a brief (13.3 ms) chromatic change in the L/(L+M) chromatic direction. The disk's presentation sequence and speed (0–16 deg/s) were manipulated. In the coherent presentation sequence, the disk moved smoothly along a circular path centered on the fixation point. In the random presentation sequence, the disk appeared randomly at positions along the circular path. In both types of sequences, the disk underwent a brief chromatic change midway through the temporal presentation sequence. Threshold was elevated in the coherent condition compared to the random condition, and threshold decreased with an increase in speed. The threshold elevation observed in the coherent presentation sequence can be accounted for by temporal integration. The decrease in threshold with an increase in speed can be accounted for by spatial integration. The results, therefore, can be explained by spatiotemporal integration, without invoking a neural mechanism specialized for motion.

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