視覺系統會利用時間的訊號群組或分離視覺環境中的不同特徵。過往的研究者認為這可能是因為同時間變化的特徵在神經系統中會被同步的處理，因此時間同步(temporal synchrony)可以做為一個區隔外在環境中不同物件的重要線索。但亦有研究指出相較於時間同步，特徵一系列變化的整體結構(即，時間結構, temporal structure)對於區隔物件的能力來說是更為關鍵的。然而，時間結構的訊號實際上同時包含了一系列時間同步的訊號加上在特徵變化時間點上的不確定性，這可能會與時間同步訊號的雜訊強度有所關聯。因此，本研究嘗試調查時間結構是否是獨立於時間同步之外的時間訊號；抑或是，時間結構實際上只是改變了時間同步訊號的雜訊強度因而改變視覺系統的判斷能力。實驗呈現一對隨機亮度的閃爍圓盤會分別根據兩個不同的時間結構改變亮度。實驗操弄了兩種時間結構的差異：固定結構(fixed structure)、抖動結構(jitter structure)。固定結構的時間結構是完全相同而抖動結構是完全不同的。兩個結構配對中的時間同步的差異量在局部是完全相同的，但是抖動結構的時間同步的方向(提前或延後)是不穩定的因此抖動結構在時間同步的訊息不確定性會相較於固定結構更高。實驗同時也操弄了時間頻率(temporal frequency). 研究總共包含兩個實驗，實驗I當中只呈現一對閃爍圓盤而實驗II中呈現一組由4乘4的閃爍圓盤組成的陣列，知覺上可以被分組成四個橫列或直行所構成。由於實驗II中的訊號來源比起實驗I更多，因此兩個實驗分別操弄了低(實驗I)與高(實驗II)兩種不同的時間同步訊號的信噪比。實驗結果發現在固定結構下，偵測時間同步的能力在高時間頻率會弱於低時間頻率；但是在抖動結構下並沒有發現這個現象。實驗I與實驗II的結果一致，但是實驗II的整體正確率高於實驗I。實驗結果表明，雖然抖動結構下的時間同步的雜訊大於固定結構，但是其偵測時間同步的能力並沒有低於固定結構，因此表示時間結構並不僅僅只是改變了時間同步訊號的雜訊強度。而且這樣現象的趨勢並不因為時間同步訊號的信噪比強弱而有所變化，表示此現象並不局限於同步訊號較不明顯的情境。因此，本研究認為時間結構的訊號應當是獨立於時間同步之外的時間訊號而且這樣的訊號會在高時間頻率下更為顯著(以本研究為例，8赫茲)。

The visual system extracts the temporal information to group and segregate different features in the space. Previous researchers have inferred that the neural system could extract the covary of the features, and therefore, the temporal synchrony is critical for segregating objects in the space. Yet, some studies showed that the overall changing pattern of a series of feature changes (i.e., temporal structure) is more critical than temporal synchrony. Nevertheless, the temporal structure embeds several bundles of temporal synchrony information and the uncertainty on the timing of feature changing simultaneously could relate to the noise of the temporal synchrony detection. Therefore, in the current study, we investigated whether the temporal structure was independent of temporal synchrony. In the experiment, a pair of flickers with random initial luminance altered the luminance followed different temporal structure separately were displayed. We introduced two differences on temporal structure, fixed structure pair and jitter structure pair. The fixed structure had the same temporal structure, but the jitter structure pair was different. At the same time, the amount of local temporal synchrony in both structures remained the same, but the jitter structure was unstable in the direction of the temporal synchrony (lead or lag), resulting in higher uncertainty of the temporal synchrony information. In addition, we modulated the temporal frequency and included two experiments. Experiment I displayed a pair of flickers, and Experiment II displayed a four-by-four flicker lattice, which could perceptually group as four rows or columns. The number of signal sources in Experiment II were greater than those in Experiment I were; thus, we modulated the low and high signal-to-noise ratio conditions. The experiment results showed the detectability of temporal synchrony was worse in high temporal frequency in a fixed structure. Contrarily, we found no detectability difference in the jitter structure. Between Experiments I and II, the tendency of performance variation was consistent, in spite of which the performance in Experiment II was higher than it was in Experiment I. The results indicated that temporal structure was not the uncertainty of the temporal synchrony because performance in jitter structure, in which the uncertainty on timing was higher, was not worse than it was in a fixed structure. This result was not restricted to a high or low signal-to-noise ratio condition and might be a general phenomenon of the temporal synchrony detection task based on luminance. Moreover, the temporal structure is more likely to be independent temporal information and a more salient cue when the temporal frequency is high (e.g., 8 Hz in our research)

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