Hack 80. Act Without Knowing It

How do we experience our actions as self-caused? It's not automatic; in fact, the feeling of consciousness may indeed have been added to our perception of our actions after our brains had already made the decision to act.

Place your hand on the table. Look at it as an object, not unlike just about anything else on the table. Now, raise one of your fingers. Why did you raise that one? Can you say? Was it a free choice? Or was the decision made somewhere else, somewhere in your brain you don't have access to? You experienced your finger being raised by you, but what was it in you that caused it?

If you record EEG readings [Hack #2] from the scalps of people just about to decide to raise their fingers and at the same time make them watch a timer and remember at what time they experienced deciding to raise their finger, they're found to report that the experience of deciding to raise their finger comes around 400 ms after the EEG shows that their brain began to prepare to raise their finger.1 Stimulating particular parts of the brain using transcranial magnetic stimulation [Hack #5], you can influence which finger people choose to move,² yet they still experience their choice as somehow willed by them, somehow "theirs."

This is an example of how an action we feel we own may be influenced by things outside of our conscious deliberation. The feeling of conscious will isn't always a good indication that we consciously willed something. And the reverse can also be true. We can disown actions we are responsible for, doing things we don't feel are caused by our own will.

In Action

Draw a cross on a piece of paper. Next, make a pendulum out of something light: a button and a length of string is ideal. Now hold the pendulum over the cross and ask a question ("Is the button on this pendulum blue?" or "Is it lunchtime yet?" perhaps). Know that to indicate "yes" the pendulum will swing clockwise, and to answer "no" the pendulum will swing counterclockwise. Don't rest your arm or elbow on anything as it holds the pendulum. Just watch the pendulum as it begins to swing to answer to your question.

Odds are, the pendulum swung in the way that answered the question correctly.

How It Works

What you've just experienced is called the ideomotor effect.³ It is the ideomotor effect that lies behind Ouija boards, dowsing wands, and facilitated communication (when helpers supposedly channel messages from the severely physically handicapped). There are no demons involved, except for the ordinary everyday human ones.

The movements produced in these cases are entirely self-caused (and, in the case of the Ouija board, self-caused and shared by a group of people)but because we don't feel we've consciously caused the movement, we're able to disown the action and it appears to have an external cause, as if it has nothing to do with us. Spooky! We do (in case you were still worried) have everything to do with it. Muscle readings from people playing with Ouija boards show that self-generated signals move the marker; the marker does not move the people's hands attached to it. Ouija boards only provide answers that the participants already knoweven if that knowledge is false. Some people have had conversations with "dead" people who have turned out to still be alive. Blindfolded participants for whom the board is rotated without their knowledge move the marker to the old, unrotated positions.

So when do we experience an action as self-caused? When don't we? Daniel Wegner of Harvard University4 has suggested that "we experience conscious will when we interpret our own thought as the cause of the action." In other words, we infer our feeling of conscious will when we notice that our intention to act went hand in hand with whatever happened. That means that if we had no such intention, the feeling of conscious will doesn't occur and, conversely, that we can feel an event was self-caused even if it had nothing to do with us. It's similar to the feeling of causation [Hack #79], which we deduce from our perception of eventswe have to, because it's impossible to perceive cause and effect directly. Our senses are all we have to work with.

Wegner suggests that the brain uses three basic principles in deciding whether to deliver an experience of conscious will: priority, consistency, and exclusivity. These are, respectively: that the thought precedes the action at an appropriate interval, that the thought is consistent with the action, and that the thought is the only candidate cause.

Now, in most situations, these conditions are met and we feel as if we properly own our actions. But in some situations, this isn't the case and we disown the action, like those of the pendulum. We make small muscle movements with the hand holding the pendulum, when thinking of the "yes" or "no" answer we expect to receivemuscle movements so small that we're barely aware that we're making them. Perhaps we would be aware of our muscles moving, except that the ultimate effect is so disproportionate: our hands move invisibly, but the pendulum swings obviously. The microthought versus the large swinging response violates the principle of consistency, and we can hardly believe that our own actions are a salient cause. That's why we don't experience self-cause and are willing to speculate about other, more proportionate, candidate causes: spirits from the afterlife and the like.

Given this, it's easy to see how behaviors that happen without much conscious will or any effort manage to escape being labeled as self-caused, such as our "monkey see, monkey do" [Hack #98] response to other people's habits.

The fact that Wegner's principles are used to understand events external to the brain isn't too surprising. After all, we have no direct way of perceiving causation in external events other than by principles like priority, consistency, and exclusivity. What is even more interesting is that the brain uses the same principles for understanding internal events like conscious action. This suggests that there are serious limits to our conscious insight into the workings of our own brains. There are good computational reasons why this should be so. You'd be distracted if you were constantly being informed of just how all your decisions were being made by your brain. Most of the processing has to be below the surface for you to operate efficiently. The ideomotor effect and related phenomenon are evidence that when it came to conscious understanding of our own actions, our brain found it more convenient to evolve a secondary set of mechanisms to infer mental causation than open up our mental modules to give us direct, but time-consuming, insight.

End Notes

1. Kornhuber, H. H., & Deeke, L. (1965). Hirnpotentialänderungen bei Willkürbewegungen und passiven Bewegungen des Menschen: Bereitschaftspotential und reafferente Potentiale. Pflügers Archiv, 284, 1-17. Discussed in Wegner, D. M., & Wheatley, T. P. (1999). Apparent mental causation: Sources of the experience of will. American Psychologist, 54, 480-492.

2. Brasil-Neto, J. P., Pascual-Leone, A., Valls-Solé, J., Cohen, L. G., & Hallett, M. (1992). Focal transcranial magnetic stimulation and response bias in a forced-choice task. Journal of Neurology, Neurosurgery and Psychiatry, 55, 964-966.

3. Wikipedia entry for the ideomotor effect (http://en.wikipedia.org/wiki/Ideomotor_effect).

4. Daniel Wegner's home page (http://www.wjh.harvard.edu/~wegner) and his book on this topic. Wegner, D. M. (2002). The Illusion of Conscious Will. Cambridge, MA: MIT Press.

Now turn to the second list of words, Table 9-6, at the very end of this chapter. Go through the second list and check/tick with a pencil those that feel familiar (if you like, you can put a cross by those you definitely didn't see).

What did you experience? Most people find that while the real words were easy to identify one way or another, certain of the nonwords had a creeping feeling of familiarity. Possibly you checked/ticked some that, in fact, you hadn't seen. If so, your recognition memory has just been royally messed with.

How It Works

This test is a good way to bring out the heuristic, fast-and-loose nature of recognition memory. When we encounter something we have experienced before, familiarity can hit us extremely rapidly. This feeling need not be accompanied by extensive memory information, which shows it isn't due to deep memory retrieval. Instead, recognition memory seems to be piggybacking on the rapid incoming sensory information to flood us with this sense of "having seen." What qualities of perception might be useful? Well, as seen before, items that have been seen recently are processed faster and more easily [Hack #81] we can call this fluent processing, or just fluency. The level of fluency you experience when you encounter something should be an ideal source of information for recognition memory; if you feel fluent in something, it's a good sign you've seen it before. But there's a problem.

Consider catching sight of your partner as you enter your home after work versus the situation in which you catch sight of a less familiar figure in an incongruous situation (say, your boss at a nightclub). The flash of familiarity comes in only the second situation, even though the first is far more common. So it turns out the fluency system is a little bit smarter. It needs to be, or we would spend our waking life overwhelmed by the familiarity of every experienced object in our environment. Other mechanisms are brought in to compensate for the high level of fluency associated with regularly encountered experiences. For example, words are processed extremely fluently, due to our dedicated language systems [Hack #49], and so the mind usually takes this extra fluency into account when presented with meaningful verbal items.

The complication in word lists like the ones in the tables is that there is no clear division between word things and certain of the nonwordlike things, the ones you felt you'd seen before. These nonwords are meaningless yet nonetheless have the structure of words and therefore feed into the mind as easily as they trip off the tongue, becoming more fluent than nonwords ought to be. This discrepancya "surprising fluency," as Whittlesea puts itfools your brain into concluding you've seen the nonwords before. The effect extends to music, with famous tunes, well-structured (catchy) and ill-structured (less musical) novel tones. The brain takes a measure of its own speed of processing (fluency) and uses that to produce smart and fast information about the environmentin this case, whether the specific experience has been had before. Well-structured tunes get falsely tagged as already heard much more than the others, because they have more fluency.

Not all false recognition research revolves around this internal measure of fluency. False familiarity can be produced by other means: for example, subjects can find the word "sleep" familiar when they have previously heard the word "snooze," because the two terms are associated, an effect known as priming [Hack #81] . The argument traditionally goes that the familiarity results not from fluency, but that, if you hear a word (and activate it in your brain), it passes on some of that activation to associated words. That's the principle behind the techniques in [Hack #85], although that's not to say that future research won't settle on an explanation based on a fluency mechanism for these false familiarity effects after all.

In Real Life

This kind of memory illusion serves advertisers well in their search for ways to get products in with the public: word-like product names are not only easier to repeat, but feel more familiar the first time around, as can musical jingles and catchphrases. Bearing in mind the slight, but real effect that mere exposure [Hack #82] can have, this makes fluency a design ambition. It could have more serious ramifications when it comes to the law, as the process of identifying criminals can involve amplification of ambiguous feelings, such as "I've seen you beforebut where?" Such feelings could be produced by preexposure to a suspect among hundreds of mug shots before a lineup or a glimpse of the subject's face in a mug shot book before the ID session has officially begun.

But we must recognize that these highlighted errors reflect a fundamental process, one essential to our day-to-day behavior, as fluent processing flips us into familiarity mode only when something in the environment falls out of line with expectations. It's a handy hack, using "norms on the fly," as Whittlesea puts it.¹

There is an ongoing debate about the localization of mechanisms upon which familiarity responses depend, with the parahippocampal gyrus (part of the limbic system [Hack #7], adjacent to the hippocampus in the temporal lobe) being touted as a candidate region. It is clear that, relative to the healthy brain, damage to temporal lobe regions impair both recognition and recall memory, but there is conflict over whether these amnesiac patients are more prone to these memory errors or actually less; this is becoming a topic of considerable interest in neuroscience.

Familiarity could be considered the cognitive equivalent of sensory pop-out (just like flat shapes that pop out into 3D using shading to emulate shadows [Hack #20] ), but our brain makes sure these things pop out only when they tend to be useful, harnessing higher-level expectations and lower-level rules of thumb to home in on the interesting features of our environment.

End Note

1. Whittlesea, B. W. A., & Williams, L. D. (1998). Why do strangers feel familiar, but friends don't? A discrepancy-attribution account of feelings of familiarity. Acta Psychologica, 98, 141-165.

See Also

· "Social Psychology Principles Can Be Used to Facilitate Eyewitness Testimony" (http://www.uplink.com.au/lawlibrary/Documents/Docs/Doc51.html).

Alex Fradera

Take a break! This is a memory test, so you need to pause for 1 or 2 minutes before reading on.

Now see if you remember your two fla__ words (it should be fairly easy) and whether they were spoken or imagined. You've got a fair chance of being right, although you'd likely make a few slips across the whole list. Try the whole list if you like, giving both items and whether you said them out loud or in your head: bre__, spe__, sal__, tar__, mon__, and spe__. It's probable that you can remember what you said for most words, and usually whether it was spoken or imagined. But while this is not an impossible task, you are in no way guaranteed to get the source of a recalled item correct.

Now in the traditional view of the mind, the idea that memories could stray from their true contextthat there is no master index putting all our memories in their placeis rather troublesome. On the other hand, consider what was done: when you come to look back, you have memories that are in most respects equivalentfor both spoken and imagined answers, you are left with a purely mental record of you saying the word. At the time, saying the word out loud was different from just imagining it, but now all that remains of both events is just an internal image of you saying the word. Yet, somehow, for the most part, we can distinguish the real event from the imaginary kind. That you've done it at all seems a testament to the memory system, as there are no obvious hooks to pull apart the problem.

Let's dig a bit deeper into this...

How It Works

If memories were itemswhole events that were fed into memory from an ideal memory systemit would be odd for us to retrieve a detail stripped of context. In the previous task, this would be knowing a word but not knowing if it were really said; but other mistakes taken from research include confusing the gender of the voice that spoke a word, or whether information was presented in the lab, learned outside it, or given in an audio or visual modality. The fact that we can make these errors pushes us to accept that memories are not holistic (read: nicely packaged) entities. Given further consideration, it is hard to imagine how they could be so and still be useful.

Consider this: how could you (or your brain) objectively and instantly demarcate the boundaries of what constitutes a single event? An event is as long as a piece of string, just as an "item" is as many features as you need to make that item. Figuring out what an "event" or "item" is, is an implausible task. If the brain were to attempt it, we would be stuck halfway to nowhere.

Once we reject this view and, in so doing, are freed to look at memories as collections of features, we can again wonder how it is that we can reconnect a memory detail with its source. This is a property memory needs to function well, so it should come as no surprise that the brain has found a solution. This is the use of multiple processes (parallel processing is a common pattern [Hack #52] ): one to allow quick automated categorization, coupled with a fact-checker to catch any major glitches and inconsistencies.

The quick system is a "heuristic" route, which relies on generalities about the mental world to make snap classifications. So, for example, there is usually a greater degree of perceptual and contextual information in perceived events relative to imagined events. Imagined images are probably sparser in content and richness of detail, so a memory that is full of detail and vividness can be quickly categorized as a good candidate for being a real memory. Even when the situations seem identical, there are subtle differences in memory quality that may be exploited; we can make comparisons in different modalities (audio/visual) to exploit different, but analogous, perceptual and contextual discrepancies.

The second, a "systematic" route, steps through the event in question, using other knowledge bases to appraise whether this labeling is consistent with wider facts (despite my gut feeling, is it really likely I had a pillow fight with Viggo Mortensen last night?) and can step in and reverse decisions made by the quick route.

A.F.

In Real Life

Great examples of source confusion abound. The pioneer neurologist Charcot's patient LeLog was convinced his paralysis was due to his legs being crushed in a traffic accident, yet this injury had never occurred and, in fact, his paralysis had no physical basis. LeLog had mentally rehearsed this situation to the extent that it began to obtain the flavor of reality, leading Charcot to coin the notion that the mind may be parasitized by suggested ideas. A less extreme outcome of source confusion in the healthy mind is unconscious plagiarism.^1,2 This is the consequence of being presented with an idea, usually in a situation in which the ownership may not be explicit or emphasized (brainstorming in a group or hearing a ditty on the radio without any clear sense of the artist), and consequently believing the idea is genuinely your own. Often the individual will rehearse and revisit the idea, and this can demolish its association with an external source or speaker. These errors can lead to merry legal escapades, especially as the accused will be unwilling to back down even in the face of incontrovertible evidence, due to the certainty we have in our own memory. Even Mark Twain, that most individual and independent-minded writer, fell foul of this.³ The same effect may lead to rather less costly squabbles, as evidenced by studies that show identical twins can dispute the possession of certain memories4; the degree of shared existence and confidences in these situations can lead to the real identity of memory protagonists being blurred.

When we turn to the abnormal functioning of the memory system, we are faced with a far more extreme example, that of patients who display confabulations.⁵ These individuals will give fanciful, false responses to questions in totally good faith, mixing details from films, current affairs, or their distant past into statements about their current activities. These individuals can be otherwise functioning fairly normally, and rationally intact, even embarrassed by inconsistencies in the memories they express, but will insist that this is what their minds are offering them. Often information that has been recently presented will be regurgitated as distinctive personal experience, the source dislocated from the item itself.

The reason that we, unlike these patients, rarely produce phantoms of this magnitude is believed to be due to a stellar monitoring and assessment system distributed within the frontal lobes of the brain. It sifts through mental items and labels them correctly as fantasy, fact, or nonsense or warns us that we do not have enough certainty to say either way. We may occasionally forget whether we were intending to turn the oven off or actually did so, but it is rare indeed that we will find ourselves confusing an intention to complete an information-rich task (say, going to visit a relative) with actually having done so.

These systems seem to be at fault within these confabulators, which, in combination with deep memory deficits, allows the creative elements of the mind to weave stories out of piecemeal elements. Confabulations seem to require damage to the two systems together: a severe problem with memory coupled with the lifting of the monitoring systems that prevent flights of fancy and other intact but irrelevant memories being crowned with the status of authenticity.

(

We should also note that, as with many memory dysfunctions, there are likely multiple kinds of confabulation. In particular, damage to the posterior orbitofrontal cortex, a structure in the anterior limbic system (the limbic system is implicated, in part, in memory. See [Hack #7] for more), is argued to cause insistent confabulation by a rather unusual route, namely damage to a motivational system.6 The idea is that memories are normally given markers that signify whether the information "pertains to now," but damage to the brain region warps this mechanism so all memories are tagged this way. Any memory brought into consciousness is accompanied by a deep subjective feeling of relevance that is normally afforded to only truly relevant information.

End Notes

1. Stark, L. J., Perfect, T. J., & Newstead, S. (2004). When elaboration leads to appropriation: Unconscious plagiarism in a creative task. Memory (in press).

2. Applied info about plagiarismhas a cognitive bent but contains lots of practical tips for teacherscan be found at http://www.psychologicalscience.org/teaching/tips/tips_0403.html.

3. Mark Twain anecdote delivered at the dinner given by the publishers of The Atlantic Monthly to Oliver Wendell Holmes, in honor of his 70th birthday, August 29, 1879 (http://www.search-engine-lists.com/marktwain/unconscious-plagiarism.html).

4. Sheen, M., Kemp, S., & Rubin, D. (2001). Twins dispute memory ownership: a new false memory phenomenon. Memory & Cognition, 29(6), 779-788.

5. See "Soul In A Bucket," a chapter of Paul Broks' Into the Silent Land (London: Atlantic Books, 2003), which features a patient who confabulates and an eloquent summary of the features of the condition.

6. Schnider,A. (2003). Spontaneous confabulation and the adaptation of thought to ongoing reality. NatureReviews Neuroscience, 4(8), 662-671 .

Alex Fradera

Do the same with the next set listed in Table 9-4: read the words aloud, then close the book and make a list.

Make your lists before reading ahead to get the most out of this hack.

Don't worry about the words you didn't get. But did your lists include either "needle" or "sleep"? If so, you should know that those two words were phantoms in your mind: They're not in either list! This is the Deese/Roediger/McDermott paradigm, or DRM,¹ and highlights how the fallibility of memory is not limited to the absence of information but includes outright fabrications. Experts believe that this doesn't represent glitches in the system but an outcome of the healthy memory systembuilt as well as needs be.

One point ought to be noted: when this technique is used, subjects are asked not to guess and typically will afterward state that they reported the "critical lure" (the lure is one of the words we asked whether you'd seen just now, but which wasn't in either list, e.g., "needle") not because they had a hunch that it could be there, but because they actually remember seeing it. In other words, there is a reported subjective experience of the word that wasn't there. This experience seems strong enough to produce better memory for the critical lures (which were never seen) than for the real items when retested two days later!

This technique can also be used to test recognition memory, but we are showcasing recall here due to the effect being so surprising, and recognition being already described [Hack #83] .

How It Works

The exact causes of this phenomenon are still up for debate. Obviously, the similarity of the listed items to the critical lure is essentialin the parlance, these words are associates of the lure. A popular argument is that items are represented in the mind in a relational network, each neighbored by its closest associates: when an item is flagged, it sends activation to surrounding nodes, and with the DRM all the critical lure's neighbors are being flagged, setting it off as surely as you could burn down a building by setting fires all around it. Sure enough, the more associates you show, the more the phantom pops out.

Interestingly enough, there have been some recent arguments that this might also be due to fluency [Hack #83], in that you actively pull the word "needle" out of memory to appraise whether it feels as if it were seen recently, and due to all the existing activation, it bubbles into consciousness quicker than it ought. The alternative view would be that when you are struggling to pick your brain for words, the ones that are selected are the most active. This may seem like a slender difference, but one is top-downsome specialist system is doing the choosingand the other bottom-up.

A.F.

What is critical to understand is that an internal representation is being elicited, without the express intention of the subject, and later being confused with an external event. In this sense it is similar to, though distinct from, the memory error described in [Hack #84] .

In Real Life

It's clear that an idea can be lodged in our heads by using backdoor techniques. A thought can be created in our minds with just inference and association, rather than by being explicitly stated.

Indeed, explicitly making a claim or suggestion can provoke people to disagree. If you are trying to persuade people of somethingsuch as your product being somehow better, brighter, or more healthyit may be better to imply an association rather than make a direct claim that can be contested.

The DRM reveals how we may bypass rational channels and achieve this end directly in memory by exploiting the brain's tendency to elicit ideas and concepts as a consequence of exposure to its associates. It suggests that the words "injection," "thimble," and "thread" may spark a thought of "needle" due, not to a leap of logic, but to the dance of association within mental networks.

This hack also serves as a circumscribed example of truly false memory. As told in other hacks [[Hack#83 and [Hack#84], events can be falsely familiar, or wrongly identified as to their sourceeven to the extent of confusing imagination with true past events. Now we see that we can produce information that really wasn't there at all. In addition, studies show that totally false but plausible events can be inserted into people's diaries and then accepted as a true event.2,3 We also know that people presented with a visual scene (such as a photograph) will often remember more of the scene than was actually presented; they fill in the scene with what makes sense to be there. It has been suggested that this phenomenon is a consequence of automatic activation of what is typically associated with this scenevery similar to the DRM situation about which we've been talking. So while we've suggested that memory may be somewhat constructed [Hack #83], these are examples in which memory is totally constructed, providing it fits into the scripts and representations we have of our lives.

Accurate memory is critical when it forms the basis of a criminal accusation. We discussed eyewitness memory [Hack #83] before, but we could also consider recovered memories, particularly those that involve alleged abuse.² Organizations have arisen to highlight how memory slips, such as filling in details that feel as though they could mesh with the situation or mistaking an imagined event for a real event, can lead to nonexperienced events seeming real. However, recent research demonstrates that we can direct ourselves to forget certain events, under the influence of frontally situated brain control systems (systems under voluntary control)that is, given a list of words, you can say to yourself "forget these words" and find those words harder to recall in the future.⁴ Given this, the idea that troubling events inevitably lead to strong and present memories isn't necessarily true, and it seems likely that recovered memories will need to be assessed on their individual basis and content.

The view of the memory system that brain and behavioral sciences have unlocked is one of distributed pattern completion. We ought to reject any notion of a veridical memory system (a memory system of statements corresponding exactly with a truthful reality). The brain doesn't favor discrete storage of information; there isn't a dusty file cabinet filled with DAT tapes stuffed with video and audio files and lists of facts.

Instead, memories are represented in the brain as networks of related features. Features that activate together cohere into a seamless, single, conscious memory. New memories are new associations in the same networks. The mechanisms that contribute to this coherencethe conscious experience of memoryare likely to be an exciting frontier in the years to come, and we hope to see neuroscientific advances combine with refinements of philosophical positions on the concepts of memory: from mental time travel (experiencing the past) to ways of knowing.

Memory may be constructed, but it works and indeed seems fairly optimal for many of our needs. It may be nonveridicalforget about any analogy of cameras rolling in our headsbut its fidelity is good enough that our past is maintained as a largely unbroken narrative, allowing us to be seated in an autobiographical identity.

Perhaps more important, the system is "good enough" to map the broad strokes of our realities: memory performs the functions we need it to. For example, our memory mechanisms mean we're particularly good at remembering the remarkable in our surroundings, and associated concepts come easily to mind. These are useful in real life. In general, it's handy that the concepts "bed" and "sheet" call the associated idea of "sleep" to mindit's only in contrived list-learning situations, such as in the previous "In Action" section, in which we'd label that as a bad thing.

End Notes

1. Roedigger, H. L., & McDermott, K. B. (1995). Creating false memories: remembering words not presented in lists. Journal of Experimental Psychology: Learning Memory and Cognition, 21, 803-814.

2. Loftus, E. F., & Ketcham, K. (1994). The Myth of Repressed Memory: False Memory and Allegations of Sexual Abuse. New York: St Martins Press. See also http://www.fmsfonline.org, a group that campaigns against recovered memory movements.

3. Schacter, D. L., Norman, K. A., & Koutstaal, W. (1998). The cognitive neuroscience of constructive memory. Annual Review of Psychology, 49, 289-318.

See Also

· Anderson, M. C., & Green, C. (2001). Suppressing unwanted memories by executive control. Nature, 410(6826), 366-369.

· Barclay, C. R., & Wellman, H. M. (1986). Accuracies and inaccuracies in autobiographical memories. Journal of Memory and Language, 25, 93-103.

· A good book on the whole issue: Schacter, D. L., Coyle, J. T., Fischbach, G. D., Mesulam, M. M., & Sullivan, L. E. (eds.) (1995). Memory Distortion: How Minds, Brains, and Societies Reconstruct the Past. Cambridge, MA: Harvard University Press.

Alex Fradera

Date: 2015-12-11; view: 614