The coin-in-the-hand test: a new "bed-side" test for the detection of malingering in patients with suspected memory disorder.

photographs of certain famous faces. His performance on the fragmented letters test' of visual perception was, however, impaired. On the cube analysis test' of visuospatial analysis his performance suggested that he was able to integrate stimuli (cubes) into spatial (three dimensional) schemas but he obtained a low score apparently due to omissions associated with neglect. He was able to draw a cube (without a model), making only slight mislocations of certain lines depicting depth. From the time of his admission to the hospital our patient presented with a profound difficulty in telling the time from a clock (or a watch), even when the clock showed a simple "on the hour" time. We investigated this impairment in two experimental sessions, two weeks and four weeks after his admission. In each session the following four conditions were used, involving time telling or clock setting for eight different "on the hour" times, chosen to represent equally the numbers on the left and right hand side of the clock. Each of eight "on the hour" times was presented twice in a random order. (1) The patient was shown a drawn clock face (diameter 12-5 cm) indicating an "on the hour" time. He was asked first to name the time, then to report the position of the clock hands and, finally, to tell the time depicted on the clock. His performance was scored as correct if he gave the appropriate answer before or after identifying the positions of the clock hands; his scores in the two sessions were: 3/16 and 0/16 (correct). (2) He was shown a drawn clock face minus the hands on which he was required to insert the hands to depict a verbally given on the hour time; he scored 16116 (correct) in both sessions. (3) The positions of the hands for an on the hour time were described verbally to the patient who was then required to say what that time was; his scores in the two sessions were 4/16 and 6/16 (correct). (4) He was given the time verbally and was then asked to say in which positions the hands should be; his scores were: 16/16 and 15/16 (correct). The results from these experiments clearly indicate a dissociation between his virtually errorless performance in conditions (2) and (4) where the response involved clock setting and his very poor performance in condition (1) where the response involved time telling from the clock face. His deficit in condition (1) occurred despite consistently accurate and unhesitating identification of the positions of the hands. When he was shown a clock face and asked to name the time, he seemed rather bewildered and reluctant to respond to the question. With encouragement he would refer to the "12" to which the long hand was pointing as the hour and the number to which the short hand was pointing as referring to the number of minutes to, or past 12 o'clock. For example, he would refer to "eight o'clock" as "eight minutes to 12" or "eight minutes past 12" and to "four o'clock" as "four minutes to 12" or "four minutes past 12". In condition (3), in which he was asked to tell the time on the basis of verbal information about the positions of the hands, his performance was better than in condition (1) but still impaired. By contrast, in conditions (2) and (4) he would respond readily and accurately, by setting the clock or giving verbally the positions of the short and long hands in the appropriate positions. Three weeks after the second experimental session his performances in conditions (2), (3), and (4) were virtually perfect and half of his responses in condition (1) were correct. Deficits in telling the time from a clock face have previously been reported in association with visuospatial neglect2 and it would be reasonable to argue that inattention to the left-hand-side underlay our patient's inability to recognise the time on a clock face. Against such an explanation would be the fact that consistently, readily, and without prompting he located accurately the numbers on the left-hand-side of the clock. He was also able to set the time on demand normally, a task that necessitates accurate search of the left-hand-side. Indeed, his satisfactory performance on other tests that are dependent on accurate recognition of (non-degraded) visual stimuli suggested that his visuospatial neglect was task specific-that is, it was mainly manifested when stimulus arrays were meaningless (for example, cancellation tests) rather than when stimuli were continuous or meaningfully integrated (for example, pictorial material depicting animals, objects, and, presumably, a clock face). 3 A particularly striking finding was that he could not identify the time from a clock face on which he himself had only just correctly inserted the hands to depict a specified time. This is akin to certain well established and apparently counter-intuitive neuropsychological syndromes involving other kinds of symbolic activity, such as dyslexia without dysgraphia and selective impairment of auditory comprehension of words in the presence of preserved ability to produce them on demand, or vice versa.4 Our data suggest that in the "telling the time" task our patient was unable to access factual knowledge about clocks and time, despite the fact that he had available to him all the relevant information. Exploration of his ability to represent visuospatial relations intemally was not possible within the time before his recovery. It is, however, relevant to add that at the time of the first set of experiments he was able to navigate us in a car through a fairly complex route in North London. This finding would normally contradict a significant distortion of visuospatial representations. As far as we know, this form of transient specific time telling deficit, in the context of accessible information about the positions of the hands on a clock face and intact ability to set the time on demand, has not previously been reported. We would like to suggest that this deficit be referred to as "horologagnosia" (from the Greek meaning an impairment of the ability to tell the time).