Arctic Monkeys - Do I Wanna Know? (Official Video)
Galina Gagin: ; Kaitlin S.
Bohon: ; Adam Butensky: ; Monica A.
Gates: ; Jiun-Yiing Hu: ; Rosa Lafer-Sousa: ; Reitumetse L.
Pulumo: ; Jane Qu: ; Cleo M.
Stoughton: ; Sonja N.
Swanbeck: ; Bevil R.
Conway: With the exception of the first author and senior author, the authors are listed alphabetically to indicate equal contribution.
Macaque monkeys click the following article a model of human color vision.
To facilitate linking physiology in monkeys with psychophysics in humans, we directly compared color-detection thresholds in humans and rhesus monkeys.
Colors were defined by an equiluminant plane of cone-opponent color space.
All subjects were tested on an identical apparatus with a four-alternative forced-choice task.
Targets were 2° square, centered 2° from fixation, embedded in more info noise.
These asymmetries may reflect differences in retinal circuitry for S-ON and S-OFF.
Introduction The macaque monkey has become a premier model for physiological studies of human visual perception, including color Conway et al.
We performed a color-detection task in both humans and rhesus macaque monkeys, under identical viewing conditions and task demands similar to those that would be used in physiological studies.
Tests of absolute detection threshold were performed on initially naïve subjects and then on the same subjects following extensive training, to control for differences in perceptual learning.
Color-detection thresholds were broadly similar across species, but surprisingly, monkey thresholds for colors that modulated L or M cones were on average slightly lower than the thresholds in humans, suggesting that monkeys see some colors better than humans.
Methods All experiments were approved by the institutional animal care and use committees at Harvard Medical School and the institutional review board http://bitcoin-casinos.top/stream/live-stream-bethel-church.html Wellesley College and adhere to guidelines of the United States National Institutes of Health.
This work followed the guidelines in the Declaration of Helsinki and the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research.
Informed consent was obtained from human participants.
Three adult male rhesus macaque monkeys Macaca mulatta and four female human subjects with normal trichromatic vision tested with Ishihara plates were trained to perform a color-detection task using standard behavioral training techniques Stoughton et al.
The tests were conducted under dark ambient light conditions on a color-calibrated CRT monitor Barco Display Systems; refresh rate 60 Hz 27 in.
Within the equiluminant plane of the color space, colors progressively further away from the origin along a vector have higher cone contrast and appear more saturated.
Colors that selectively modulate the L and M cones are depicted along the x-axis, while colors that modulate the S cones pitted against the sum of L + M are depicted along the y-axis.
Colors that are intermediate to these cardinal axes modulate the activity of all three cone types.
The task design was similar to that described by Stoughton et al.
A Left: Stimuli colors defined by the cardinal axes of cone-opponent color space Derrington et al.
The monkey and human subjects were trained on the same apparatus to fixate on a small spot at the center of a monitor displaying full-field neutral gray.
The trial was initiated after the subject started fixating on the center spot.
After 500 ms, the fixation spot disappeared and a 2° square target spot appeared at one of four locations, centered 2° from the center of gazeright panel.
Of those trials conducted after perceptual learning was exhausted, humans aborted 0.
Monkey subjects were rewarded with a juice drop and a beep, and different colored monkeys subjects with a beep alone, for directing their gaze to the target live v stream west ham everton />Eye movements were monitored using an infrared camera tracking system ISCAN.
A trace from a sample session is shown in left.
Subjects showed no obvious bias in target locationright.
Headposts were secured to the animals' skulls Stoughton et al.
Human subjects used a chin rest.
A 14-bit digital to analog converter Bits++, Cambridge Research Systems, Rochester, England drove the stimuli, which were generated using MATLAB code generously provided by Hansen and Gegenfurtner and calibrated with a PR 655 spectroradiometer Photo Research Inc.
During testing, the target could vary in color and contrast azimuth and radial length in the cone-opponent space, but maintained photometric equiluminance 46.
The smaller eyes of monkeys compared to humans may have caused a slight difference in the retinal light flux; consequently, the mean retinal luminance might be slightly different for the two species.
This is unlikely to have introduced any systematic difference in detection thresholds because the stimuli were embedded in luminance noise.
Trials with targets of different color and saturation were pseudorandomly interleaved, maintaining roughly the same total number of trials of each target within a given session and ensuring that no performance biases could accumulate for a given color.
A trial was included in the analysis if the subject did not break fixation during the fixation period and transferred gaze to one of the four possible target locations.
The psychometric curves were fit with a Weibull function : using the maximum-likelihood criterion, where α is the threshold value and β is the slope of the fit.
The threshold α corresponds to 63% between guess rate and lapse rate.
Thresholds for individual colors were calculated at the end of each session and a reciprocal curve fit was used to describe performance over time.
Plateau performance was defined by the crossing of the standard deviation of the threshold value and the asymptote value of the curve fit.
There were no striking differences in the lapse rates between the two species, suggesting that the motivational states of the subjects were comparable; moreover, performance on maximum-saturation targets was no different across different colors see andconfirming that motivational state did not vary systematically by color an unlikely possibility in any event, since trials of different color were randomly interleaved.
Reaction times for detecting chromatic targets.
Average monkey black and human gray response-time histograms averaged over all colors for a given saturation level.
Reaction times were calculated for correct trials except in the gray condition, when.
Psychometric curves for the detection of eight colors evenly sampling the equiluminant color plane, for monkeys and humans, using stimuli embedded in 0.
Average monkey black and average human gray performance is shown for.
In pilot experiments, we tested the subjects using 2°-diameter circular targets on uniform gray backgrounds.
The spots had 0.
The conclusions from these experiments are similar to those described here, with the exception that the monkeys had peculiarly low thresholds for some colors notably color 5, ; see for a summary of the results from the pilot experiments.
We attribute these anomalous results to luminance artifacts, which are controlled by embedding the stimuli in luminance noise Mullen et al.
To generate the luminance noise in the experiments described presently, the screen was divided into checks that were 0.
The luminance of each live streaming arsenal vs hotspur was randomly assigned to be matched source the mean luminance of the display or 10% or 20% higher or lower, and this assignment changed dynamically several times a second.
Impact of luminance noise on chromatic-target detection threshold.
Average human threshold values are shown as the distance from the origin for each color direction obtained in Experiment 1 thick solid line; 0.
Results We tested psychophysical performance on a chromatic-detection task in three monkeys and four humans.
Two of the monkeys M1, M2 and three of the humans H1, H2, H3 were naïve to the task at the beginning of the present experiments; one experienced psychophysical observer H4 participated in an extensive series of pilot experiments and was the best subject among eight humans tested; and one monkey M3 also participated in the pilot experiments.
M1 and M2 performed an average of 2,576 detection trials per session, in 15 sessions over 2 months.
M3 showed stable thresholds over a yearlong gap in training between the pilot experiments and the present experiments ; M3 was tested for an average of 3,136 detection trials per session for five sessions in the present experiments.
H1, H2, and H3 performed an average of 1,960 trials per session, and an average of 13 sessions over 3 months; H4 performed an average of 759 trials per session and four sessions on the present experiments but was overtrained on a very similar task in the pilot study.
During the course the knight rises free stream the experiments, all subjects became overtrained on the task, exhausting perceptual learning.
The time point at which perceptual learning was exhausted and plateau performance was obtained was defined as the crossing of the standard deviation of the threshold value and the asymptote value of the curve fit to the data ; Stoughton et al.
Contrast of the target is given in cone-contrast units as well as device-dependent units D.
As expected, target-detection performance increased with increasing target saturation for monkeys and humans.
The black lines are shifted to the left, showing that training reduced the detection thresholds.
Distances further from the origin show a greater learning effect.
Performance on color-detection task improves with training, monkey data A and human data B.
Left: Psychometric detection curves from a single session for color 1 blackened square in the icon inset identifies the color shown infor an.
Change in chromatic-detection thresholds with task training.
A The distance from the origin shows the log difference between the detection threshold obtained on the first two testing sessions and that of the last two testing sessions, for the colors.
As expected, trials with the most saturated stimuli were associated with shorter reaction timesleft panel than trials with less saturated stimuliright panel.
Monkeys showed shorter reaction times than humans for all stimuli compare black bars and gray bars.
All the data points are less than 1, reflecting the observation that monkey reaction times were shorter than human reaction times to all stimuli; the data point corresponding to the most saturated stimuli approaches 1, showing that the differences in reaction times between monkeys and humans are reduced for the most visible targets; and the data points typically lie above the unity diagonal, showing that monkey reaction times to LM targets were relatively shorter than reaction times to S targets.
Monkeys detect colored targets of all saturations faster than humans, and faster still for colors along the LM axis.
The black and gray curves are overlapping in the bottom panels, showing that monkeys and humans had similar detection thresholds for S colors.
Psychometric curves for individual subjects are in.
Data points that are further from the origin correspond to larger detection thresholds i.
On average, the black lines monkey subjects tend to sit inside the gray lines human subjects for all colors except those that selectively modulate the S cones asterisks show significant differences between the species; significance was achieved if the 95% confidence interval of the threshold values between the two species did not cross.
These results show that chromatic stimuli that were often invisible to humans were visible to monkeys.
The absolute value of the cone contrast of the stimuli required to reach threshold is shown in and.
Detection thresholds for chromatic targets embedded in 0.
A Average threshold value in device-dependent units and cone-contrast units see for formulashown as the distance from the origin for each color direction.
The results shown in and were obtained using 2° targets embedded in 0.
To control for this possibility, we performed an additional experiment with two of the monkeys and two of the humans.
The targets were the same size as in Experiment 1 but were embedded in 2° luminance noise.
The targets were spatially registered to the luminance noise checks; any uniform luminance pedestal would therefore be masked.
The human subjects reported that the task in Experiment 2 seemed a little more difficult than the task in Different colored monkeys 1.
Consistent with this report, human detection thresholds were slightly higher on average for the experiment using 2° noise more data points sit above the unity diagonal in.
Monkey thresholds were also higher for this experimentand higher than the differences observed in humans, reflecting the increased task difficulty.
Psychometric curves for the detection of eight colors evenly sampling the equiluminant color plane, for monkeys and humans, using stimuli embedded in 2° luminance noise.
Detection thresholds for chromatic targets embedded in 2° luminance noise.
Inset shows an icon of the stimulus.
Detection thresholds increase when targets are embedded in 2° versus 0.
Error bars show standard deviation of the calculated threshold value.
Color of marker corresponds to the hue.
In we compare the results obtained presently with those obtained during the preliminary pilot experiment, to gain some sense of the impact of the luminance noise on chromatic sensitivity.
In the pilot experiment, targets were 2° discs with 0.
Other aspects of the psychophysical paradigm, including eye monitoring, were similar to those for the experiments described previously.
All subjects were overtrained, and detection thresholds were assessed after plateau performance.
Discussion and conclusion The similarity in cone sensitivities found in monkeys and humans supports the use of monkeys as a model of human color vision Conway et al.
But color perception depends on many computations implemented downstream of the cones Conway.
In order to use monkeys to test hypotheses of how this circuitry functions to bring about color perception and cognition, it is important to directly compare psychophysical behavior in the two species Stoughton et al.
Here we performed tests of one of the simplest color tasks: detection of chromatic targets.
For the most part, monkeys and humans had very similar color-detection thresholds.
This subtle species difference may arise because of differences in the cone fundamentals between the two species; alternatively, the difference may reflect the evolutionary trade-off between color acuity and spatial acuity, as discussed later.
The data also showed, for both species, a systematic difference in the magnitude of task improvement over time between S increments more improvement over time and S decrements less improvement over time.
We conclude that while monkeys may not be an identical model of human color vision, they are nonetheless an excellent system for investigating physiological mechanisms of human trichromatic color vision.
Prior measurements of absolute color detection in monkeys and humans have suggested that monkeys have similar or possibly worse color abilities than humans see.
To our knowledge, the present report is the first to use equiluminant stimuli presented under careful click control to directly compare the abilities in the two species on the same task and apparatus.
We assume that the subtle species difference would remain if the task were altered such that the targets were presented at the fovea, but we have not different colored monkeys this.
The stimuli were embedded in luminance noise, which masks luminance artifacts; and trials of different colors were randomly interleaved, so it would be impossible for the animals to show selectively higher motivation or attention on trials with some colors.
The stimuli used on both species were identical, generated using human cone fundamentals that are widely used in both human psychophysics and monkey physiology.
It remains unknown to what extent these fundamentals are appropriate for use in experiments with monkeys.
That we obtain very similar detection-threshold measurements in monkeys using stimuli that assume human cone fundamentals suggests that the use of human fundamentals for physiological and psychophysical experiments in monkeys will not introduce grave errors.
It remains to be tested whether humans showing more balanced L:M cone ratios show lower color-detection click the following article, as this theory predicts McMahon et al.
Taken together, the present results raise the possibility that evolutionary selective pressures have resulted in slightly higher chromatic sensitivity among macaque monkeys compared to humans, at the cost of spatial acuity.
The S-cone mosaic may also be subtly different in monkeys and humans.
Despite the species differences in S-cone mosaics, we found no difference in S-cone detection thresholds between monkeys and humans.
The polar plots and reveal a striking asymmetry in the detection thresholds for colors that modulate all three cone types i.
continue reading observation is consistent with lack of probability summation i.
The present experiments provide some insight into the time course of perceptual learning for chromatic targets.
Access to this information is difficult to obtain from previous comparative experiments, which often used aversive conditioning that over time engenders a long-term avoidance response to the testing situation.
The present results show that subjects needed a variable number of sessions to reach plateau performance for different colors, but that the range was the same between monkey and human subjects one to seven sessions.
Once plateau performance was achieved, optimal performance was maintained across long time gaps in task activity.
These observations read article a psychophysical correlate of the physiological and anatomical differences in S-ON and S-OFF circuitry.
Although previously reported values for detection thresholds for S increments and S decrements are similar Bosten et al.
But this trend was not significant after extensive trainingsuggesting that the differential impact of learning on targets of different colors depends, to some extent, on computations in the cortex.
The results described presently were obtained by testing detection thresholds at one different colored monkeys eccentricity 2° using relatively large targets 2° square.
This eccentricity corresponds to a region with dense macular pigmentation Snodderly et al.
Macular pigmentation functions as a preretinal chromatic filter and impacts the color-matching functions used to define the equiluminant stimuli.
The extent and makeup of macular pigmentation is different in monkeys versus humans, which may introduce luminance artifacts especially with stimuli that modulate S cones.
The similarity of detection thresholds in the two species, particularly to S-cone-modulating stimuli, suggests that differences in macular pigmentation are unlikely to be problematic.
But in order to adequately address this issue, detection-threshold tests must be done across the visual field G.
Horwitz, University of Washington, personal communication, April 25, 2014.
This work was supported by the National Institutes of Health EY023322the National Science Foundation 0918064and Wellesley College.
We thank David Hubel and John Maunsell for providing lab space, and Thorsten Hansen for MATLAB code to do the color calibration.
We thank Greg Horwitz and the anonymous reviewers for constructive comments, and the members of the Harvard Vision Group for useful discussion, especially Richard Born for suggesting Experiment 2.
Corresponding author: Bevil R.
Address: Neuroscience Program, Wellesley College, Wellesley, MA, USA.
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Kipling stop motion - The 4 color monkeys
For nearly a decade, Smith and his colleagues have ventured into the Peruvian Amazon to study how different types of sight affected the foraging behavior of New World monkeys called tamarins. Humans have so-called trichromatic, or three-color, vision. So do Old World species such as chimpanzees, ...
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