Python/Psychopy : getKeys collecting keys too early

Question

在下面的代码中，我显示 pic1 3 秒，然后显示固定十字 1 秒，然后显示 pic2 直到用户按下某个键。据我所知，它应该只在我的第三个“for”循环中收集按键，因为这是我创建按键列表并检查按键等的地方。但是，如果我在 pic1 或固定十字期间按下一个按键，如一旦 pic2 出现，它就会立即继续执行代码。它似乎在我的第三个“for 循环”之前注册按键，然后在我的第三个“for 循环”发挥作用时产生效果。我不明白这是如何发生的，因为我在显示 pic1 和固定期间没有检查任何键。有人可以在这里启发我吗？也许我误解了 getKeys 的一些基本原理。

-如果我不按任何键，则会发生预期的行为..它会显示 pic2 并等待按键。仅当按下某个键或经过 60 秒时，它才会继续执行代码(我已将图像设置为显示 60 秒，用户预计会在前 5 秒内做出响应，因此 60 秒只是安全值)。

def block1():

    running = 1

    while running ==1:

        for frames in range(image_frames):   #3 seconds
            pic1[0].draw()
            window.flip()

        for frame in range(fixation):        #1 second
            fix.draw()
            window.flip()

        for frames in range(stim_Frame):   #only moves on with keypress (or 60 secs)
            pic2[0].draw()
            start = window.flip()
            if frames == 0:
                stim_time = start
                print "stim time: "
                print stim_time

            allKeys = event.getKeys(keyList = ('f','h','escape'))
            for thisKey in allKeys:
                if thisKey == 'escape':
                    print "you quit"
                    window.close()
                    core.quit()
                if thisKey == 'f':
                    keyTime=core.getTime()
                    thisResp = 1      
                    print "keytime is: "
                    print keyTime

                elif thisKey == 'h':
                    keyTime=core.getTime()
                    thisResp = 0
                    print "keytime is: "
                    print keyTime

            if thisResp == 1 or thisResp == 0:
                break

        running = 2

    window.flip()

干杯，史蒂夫

Answer 1

event.getKeys() 返回其内存缓冲区中存在的所有键。在第三次循环之前清除该缓冲区。

def block1():

    running = 1

    while running ==1:

        for frames in range(image_frames):   #3 seconds
            pic1[0].draw()
            window.flip()

        for frame in range(fixation):        #1 second
            fix.draw()
            window.flip()

        event.clearEvents()  # Clear the previously pressed keys.

        for frames in range(stim_Frame):   #only moves on with keypress (or 60 secs)
            pic2[0].draw()
            start = window.flip()
            if frames == 0:
                stim_time = start
                print "stim time: "
                print stim_time

            allKeys = event.getKeys(keyList = ('f','h','escape'))
            for thisKey in allKeys:
                if thisKey == 'escape':
                    print "you quit"
                    window.close()
                    core.quit()
                if thisKey == 'f':
                    keyTime=core.getTime()
                    thisResp = 1      
                    print "keytime is: "
                    print keyTime

                elif thisKey == 'h':
                    keyTime=core.getTime()
                    thisResp = 0
                    print "keytime is: "
                    print keyTime

            if thisResp == 1 or thisResp == 0:
                break

        running = 2

    window.flip()