phantabulation: a case of visual imagery interference on visual perception

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This article was downloaded by: [University of Chicago Library] On: 13 November 2014, At: 00:24 Publisher: Routledge Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Neurocase: The Neural Basis of Cognition Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/nncs20 Phantabulation: A case of visual imagery interference on visual perception Gianna Cocchini ab , Owen Lello b , Robert D. McIntosh c & Sergio Della Sala c a Department of Psychology, Goldsmiths University of London, London, UK b Department of Psychology, Blackheath Brain Injury Rehabilitation Services, London, UK c Human Cognitive Neuroscience, Department of Psychology, University of Edinburgh, UK Published online: 21 Aug 2013. To cite this article: Gianna Cocchini, Owen Lello, Robert D. McIntosh & Sergio Della Sala (2014) Phantabulation: A case of visual imagery interference on visual perception, Neurocase: The Neural Basis of Cognition, 20:5, 581-590, DOI: 10.1080/13554794.2013.826689 To link to this article: http://dx.doi.org/10.1080/13554794.2013.826689 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions

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This article was downloaded by: [University of Chicago Library]On: 13 November 2014, At: 00:24Publisher: RoutledgeInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: MortimerHouse, 37-41 Mortimer Street, London W1T 3JH, UK

Neurocase: The Neural Basis of CognitionPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/nncs20

Phantabulation: A case of visual imageryinterference on visual perceptionGianna Cocchiniab, Owen Lellob, Robert D. McIntoshc & Sergio Della Salac

a Department of Psychology, Goldsmiths University of London, London, UKb Department of Psychology, Blackheath Brain Injury Rehabilitation Services,London, UKc Human Cognitive Neuroscience, Department of Psychology, University ofEdinburgh, UKPublished online: 21 Aug 2013.

To cite this article: Gianna Cocchini, Owen Lello, Robert D. McIntosh & Sergio Della Sala (2014) Phantabulation: Acase of visual imagery interference on visual perception, Neurocase: The Neural Basis of Cognition, 20:5, 581-590,DOI: 10.1080/13554794.2013.826689

To link to this article: http://dx.doi.org/10.1080/13554794.2013.826689

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”)contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensorsmake no representations or warranties whatsoever as to the accuracy, completeness, or suitabilityfor any purpose of the Content. Any opinions and views expressed in this publication are the opinionsand views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy ofthe Content should not be relied upon and should be independently verified with primary sources ofinformation. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands,costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly orindirectly in connection with, in relation to or arising out of the use of the Content.

This article may be used for research, teaching, and private study purposes. Any substantial orsystematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distributionin any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found athttp://www.tandfonline.com/page/terms-and-conditions

Neurocase, 2014Vol. 20, No. 5, 581–590, http://dx.doi.org/10.1080/13554794.2013.826689

Phantabulation: A case of visual imagery interferenceon visual perception

Gianna Cocchini1,2, Owen Lello2, Robert D. McIntosh3, and Sergio Della Sala3

1Department of Psychology, Goldsmiths University of London, London, UK2Department of Psychology, Blackheath Brain Injury Rehabilitation Services, London, UK3Human Cognitive Neuroscience, Department of Psychology, University of Edinburgh, UK

We report the case of a 52-year old man who, following rupture of an anterior communicating artery aneurysm,presented with a phenomenon not previously described, which we have labelled “Phantabulation.” Phantabulationis characterized by frequent and purposeful interactions with contextually appropriate imagined objects. We sug-gest that this phenomenon results from confusion between real and imagined objects, caused by failure to inhibitflorid visual imagery, facilitated by cortical release mechanisms.

Keywords: Visual imagery; Perception; Confabulation; Stroke.

We report on the case of patient MT who, fol-lowing the rupture of an anterior communicatingartery aneurysm, presented with a phenomenon notpreviously reported. He mimed actions with non-existent objects, interacting with them appropri-ately to the context, and confabulating about them,in the absence of any signs of classic hallucinations.For example, he would appear to smoke a cigaretteand extinguish it in an ashtray, though neitherobject was present. When asked to draw, he reachedas if for the real pencil on the table, but thenmimed the picking up and drawing actions, leav-ing no visible marks on the paper. He ignoredthe fact that his actions had no actual results andcould provide detailed sensory descriptions of the(phantom) objects with which he was interacting.On direct, repeated questioning, he was able toachieve insight into the imaginary nature of theseobjects; yet, he showed remarkably little concernabout this behavior. We have termed this phe-nomenon “Phantabulation,” echoing a label givento the complex hallucinations of Charles Bonnet

Address correspondence to Gianna Cocchini, Psychology Department, Goldsmiths University of London, New Cross, London SE146NW, UK. (E-mail: [email protected]).

We are grateful to Nicoletta Beschin for her help in mapping the patient’s lesion reconstructed in Figure 1.

syndrome: “Phantom visual images” (Schultz &Meltack, 1991).

CASE REPORT

MT (not his real initials) is a right-handed (lat-erality quotient = 0.79; Oldfield, 1971) man with11 years of formal education, who at the timeof testing was 52 years old. He had a historyof untreated anxiety. Prior to his stroke, he hadbeen a heavy drinker and smoked cannabis reg-ularly. He was admitted to hospital for the rup-ture of an aneurysm of the anterior communi-cating artery. An external ventricular drain wasinserted immediately and coil embolization of theright anterior communicating artery was performedon the following day. A series of neuroimagingscans (see Figure 1) performed 10 days after thevascular accident showed a right ventro-medialfrontal and intraventricular hemorrhage. As is typi-cal in hemorrhages (Catani, et al., 2012), the lesion

c© 2013 Taylor & Francis

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582 COCCHINI ET AL.

Figure 1. Reconstruction of MT’s area of lesion (MRIcro, www.mricro.com, Rorden & Brett, 2000) at 10 days post-stroke. The patient’slesion was superimposed onto a 2D axial rendering on the Montreal Neurological Institute (MNI) representative brain in stereotacticspace. Note that the right side of the reproduction corresponds to the right side of the brain. [To view this figure in color, please visit theonline version of this Journal.]

also damaged white matter tracts, including shortfrontal lobe connections (Catani, et al., 2012) aswell as the longer arcuate fasciculus (Catani &Thiebaut de Schotten, 2008).

On clinical examinations, the patient provedblind in the right eye, in line with pre-chiasmaticdamage; he did not show motor or somatosensorydeficits, his proprioception was also normal.

MT came to our attention 2 months later, whenhe was transferred to the brain injury rehabilita-tion ward. He appeared as an intelligent man with agood understanding of social context, able to makeoccasional subtle and appropriate humorous jokes.General examination was part of routine assess-ment but informed consent was obtained to furtherinvestigate some aspects of his cognitive deficits.

COGNITIVE ASSEMENT

MT’s performance at formal assessment is reportedin Table 1. He was disorientated to time and space:he committed gross errors in estimating the currentdate, including the year and the month; he fre-quently got lost in the ward and was unable to findhis room or familiar communal rooms. There wasno evidence of verbal short-term memory impair-ment, simultanagnosia, neglect, or constructionalapraxia. He performed poorly on most sub-testsof the visual object and space perception battery(VOSP) and just above cut-off on Street’s com-pletion task, which assesses visual perception ofdegraded figures. He responded correctly when pre-sented with classical illustrations to assess amodalperception (i.e., perception of a complete struc-ture when only some of its parts are presented).He performed very well on visual imagery tests,with ceiling performance on two of the three sub-tests of the visual imagery test battery (object sizesand object colors). MT showed persistent long-term memory impairments and deficits on executivetests. When asked about his problems, he mentionedonly some vision and memory difficulties.

Verbal continuous recognition task

To avoid interference from visual perceptual prob-lems, a verbal version of the classical contin-uous recognition task by Schnider and Ptack(1999) was devised. Names of objects illustratedin the Snodgrass and Vanderwart pictures (used inthe original test) were read aloud, and MT wasrequired to say whether each word had alreadybeen presented in that current run. There were fourruns, and each of them consisted of eighty wordswithin which four target words were repeated eighttimes each. Run 2 was given immediately after thefirst run, with Run 3 after a 5-minute break andRun 4 after a further 30 minutes. At the begin-ning of each run, MT was explicitly instructed todetect targets repeated on the current run only. MTshowed a dramatic increase in false alarms (FAs)between Run 1 and subsequent runs (i.e., when pre-vious targets where now functioning as distracters)(see Table 1). He tended to falsely recognize previ-ously encoded stimuli as current targets, suggestinga difficulty in suppressing previously acquired infor-mation.

Source monitoring test

Some authors have observed that even healthyvolunteers, especially older people, may have dif-ficulties in discriminating between external andinternal sources of information (e.g., Johnson, DeLeonardis, Hashtroudi, & Ferguson, 1995). These“reality monitoring errors” may occur if mem-ory traces derived from imagination are mistakenlyidentified as referring to an actual percept. To assesswhether Phantabulations may, at least in part, resultfrom reality monitoring errors, MT and five age-matched healthy controls (average age 60.0, SD= 3.5) were given a modified version of Henkel,Johnson, and De Leonardis’ (1998) test. They wereasked to view a series of 30 large stimuli. Halfof the stimuli (Perceived condition) consisted ofa concrete word with the related black and white

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PHANTABULATION 583

TABLE 1MT’s performance on a battery of cognitive tests

Test1 MT scores #Cut-off test/interpretation

Repeatable battery for the assessment of neuropsychological status Cut-offImmediate memory—index score (0–130) 57 80Visual/constructional—index score (0–130) 50 80Language—index score (0–130) 75 80Attention—index score (0–130) 85 80Delayed memory—index score (0–130) 40 80Total score—index score (0–130) 52 80Addenbrooke’s cognitive examinationAttention and orientation (0–18) 15 17Memory (0–26) 12 18Fluency (0–14) 9 9Language (0–26) 26 24Visuo-spatial (0–26) 12 15Total score (0–100) 74 86Verbal short-term memorySpan forward (0–16) 7 4Span backward—(0–14) 6 4Street’s completion testCorrected score (0–14) 3.25 2.25Constructional apraxia testCorrected score (0–14) 11.75 8Visual imagery testColor (0–25) 25 22.7∗∗∗Animal’s tails (0–20) 15 14.8∗∗∗Size comparison (0–16) 16 16∗∗∗Visual object and space perception battery Test interpretationScreening test (0–20) 18 PassIncomplete letters (0–20) 9 FailSilhouettes (0–30) 8 FailObject decision (0–20) 2 FailProgressive silhouettes (0–20) 16 FailDot counting (0–10) 1 FailPosition discrimination (0–20) 17 FailNumber location (0–10) 6 FailCube analysis (0–10) 3 FailVisual illusionsAmodal completion3D cube behind bars “a cube with bars on it” Normal completionFour black circles partially covered by rectangles “4 circles and 4 rectangles” Normal completionNeglect testsLine cancellation (0–40) ∗∗ No evidence of neglectDrawings from memory (house, person, flower) (0–3) 3 No evidence of neglectSimultanagnosia testColor test (random, single, and mixed conditions) (0–6) 6 No evidence of

simultanagnosiaLine length test (complete and separate shapes) (0–6) 16 No evidence of

simultanagnosiaStroop test##

Colored letters (0–6) 6Neutral (0–9) 9Congruent (0–6) 6 Ceiling performanceIncongruent (0–6) 6 Ceiling performanceHayling and Brixton testHayling—overall scaled score (1–10) 4 Low averageBrixton—overall scaled score (1–10) 2 Abnormal

(Continued)

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584 COCCHINI ET AL.

TABLE 1. Continued.

Test1 MT scores #Cut-off test/interpretation

Continuous recognition task—verbal versionHits % FAs %

Run 1 89 6 == =Run 2 (immediately after) 75 78 FAs after Run 1 suggests

deficit in suppressingpreviously encoded

informationRun 3 (5 minute delay) 93 60Run 4 (30 minute delay) 86 67

#Abnormal test performance is indicated in bold. ∗∗MT cancelled the lines without touching the sheet so no mark was left. Fromdirect observation, MT clearly attended to all stimuli. ∗∗∗Cut-off scores represent the value at 2 SDs from age-matched controls’ averageperformance. Data taken from Hanley, Young, and Pearson (1991). ##Patients’ responses were very quick. At the end of the test, MTadded: “I concentrated on the task and ignored the different colour.” FAs = False Alarms.1Repeatable battery for the assessment of neuropsychological status (Randolph, 1998); Addenbrooke’s cognitive examination—revised(Mioshi, Dawson, & Mitchell, 2006); Verbal short-term memory (Wechsler, 1997); Street’s completiontest (Spinnler & Tognoni, 1987);Contrustional apraxia test (Spinnler & Tognoni, 1987); Visual imagery test (Hanley et al., 1991); Visual object and space perceptionbattery (Warrington & James, 1991); Visual illusions (taken from Kaniza, 1980, figures 2.4 and 2.6); Neglect tests (from BIT; Wilson,Cockburn, & Halligan, 1987); Simultanagnosia Test (Humphreys & Riddoch, 1993); Stroop test (Stroop, 1935); Hayling and Brixtontest (Burgess & Shallice, 1997); Continuous recognition task (Schnider & Ptak, 1999).

line drawing displayed underneath it (e.g., the word“APPLE” with a picture of an apple below it);the other half (Imagined condition) consisted ofa concrete word only (e.g., the word “BOX” writ-ten without any picture). Stimuli for Perceived andImagined conditions were piloted to balance themfor physical and semantic similarity.

Stimuli from each condition were displayed for6 seconds each, in random order, and partici-pants were asked to estimate how many secondsit would have taken to draw the picture indicatedby the word. This drawing time estimation taskwas used to induce a mental image of the stim-ulus. Participants were then engaged in a generalconversation for 15 minutes, after which they weregiven a surprise memory test in which the 30 wordswere re-presented, shuffled randomly with 15 newconcrete words. For each word, participants were

asked to state whether it had been presented ear-lier with a picture, had been imagined, or wasnew.

MT identified most of the perceived stimuli cor-rectly, but erroneously classed many imagined andnew stimuli as previously perceived (see Table 2).Misidentifications of imagined and new stimuliwere, respectively, 7 and 17 standard deviationshigher than those of the matched controls. Thisstrong tendency to misidentify even new stimuli asperceived suggests that MT elicited strong visualimages of the object not only in memory but evenduring stimulus word viewing. This is supportedby a chance observation made during a practicetrial: the examiner pointed out that, for a word thatMT had just read, there was no image and MThad to imagine one, to which MT commented withsurprise, “Oh...there isn’t one!”

TABLE 2MT’s and matched controls’ performance on the source monitoring test

Perceived stimuli recognized as Imagined stimuli recognized as New stimuli recognized as

Perceived Imagined New Perceived Imagined New Perceived Imagined New

MT 86.7∗ 6.5 6.5 46.7∗∗ 26.7 26.7 53.3∗∗∗ 13.3 33.3Healthy controls Mean 72.0 12.0 16.0 5.3 90.7 4.0 1.3 2.7 96.0

SD 19.1 11.9 10.1 5.6 3.7 3.7 3.0 3.7 6.0

Correct responses are underlined. ∗Within 1 standard deviation from norms; ∗∗7.4 standard deviations higher than norms; and∗∗∗17.4 standard deviations higher than norms.

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PHANTABULATION 585

OBSERVATIONS OF “PHANTABULATIONS”

Phantabulations occurred quite regularly and didnot appear to be specific to any situation, time,or location. They could occur spontaneously dur-ing a conversation with the examiners, relatives, orfriends and sometimes during formal test sessionsthat were video or audio recorded, allowing for laterevaluation and transcription. Phantabulations weremainly linked to visual information, and MT neverreported auditory hallucinations. However, someinvolvement of somatosensory modalities was occa-sionally observed. On one occasion, for instance,MT held an imaginary bottle, commenting “it’squite light.” Phantabulations could be triggered bya variety of stimuli, which could be either endoge-nous (e.g., talking about or imagining an object)or exogenous (e.g., seeing a basin could triggerMT to begin brushing his teeth with an imaginarytoothbrush).

Nevertheless, simply asking MT to imagine anobject did not necessarily trigger a Phantabulation.On a few occasions, MT was asked to look at awhite sheet and to imagine that some drawings (i.e.,either a picture of a house or a clock) were illus-trated on it. He was then encouraged to enrich eachimage by responding to some questions about color,size, pleasantness, or the position of details (e.g.,“Point to the windows of the house” or “Point tothe digits of the clock”). MT’s visual imagery wasvery good; he provided clear plausible responsesand showed a good ability to form and manipulatevisual images. However, when asked whether therewas a drawing on the sheet in front of him, he said“ . . . there is nothing here . . . it’s all my imagi-nation.” Similarly, Phantabulations were not easilyinduced by looking at another person’s behavior.During a testing session, the examiner pretended tograsp a box of sweets from a shelf, to pick one outand unwrap it; then, MT was asked to kindly putthe wrapper in the bin. MT looked puzzled, he heldout his hand to get the paper and then asked “Arewe pretending?”

By contrast, when MT generated a mental imageeither spontaneously or in response to currentneeds, this often induced Phantabulations, as onnumerous occasions when he was asked to drawpictures or write his name. MT would usually pickup the real pencil but mime the act of drawing inthe air just above the sheet, leaving no trace onthe paper. When questioned about his drawings,he would answer questions and point toward spe-cific details of his “drawing.” MT seemed convinced

by his “perception” of reality, and he was per-plexed when contradictory evidence was presented.Indeed, MT acted in accordance with his erroneousbeliefs even in more intimate situations. On oneoccasion, for example, a nurse guided him to thetoilet door, as he had some difficulty in finding hisway there. Once alone in front of the toilet door,he started to undress himself to sit on an imagi-nary toilet. The nurse quickly came back to guidehim inside of the room, at which MT looked per-plexed, as if he could not understand why he wasbeing asked to move.

These effects were quite robust and long-lasting.On several occasions, MT failed to acknowledgeexplicitly that his drawing was only imagined,despite occasionally showing some insight. On oneoccasion, while drawing a clock face, he sponta-neously put down the pencil and commented “Mydrawing is weird, you know? . . . a clock shouldbe with numbers 1, 2, . . . .” Another time, aftera long conversation about a (phantom) drawing,the examiner asked him, “If I showed this drawingto T [another examiner observing the examination]would he be able to tell what has been drawn onthis sheet?” MT replied, “It would be amazing ifhe could,” and only after several questions aboutthe reason for this, MT added “ . . . because thereis nothing there!” After this statement he immedi-ately stopped smiling and he looked at the sheet ina perplexed manner.

Some further interesting aspects of MT’s behav-ior are illustrated by the following episode. Duringa testing session, MT complained of having aheadache and asked permission to take a painkiller.He then pretended to pull out with his right handfrom the left pocket of his jacket a pill dispenser,to take one of them and to drink some water froma glass, though none of these objects were presentin the room. The following (taped) conversationensued:

Examiner: “How do you know . . . that these arethe correct pills?”

MT: “I recognise them”

Examiner: “You recognise them from what?”

MT: “Well paracetamol is paracetamol . . . onceyou get to know them you can spot them fromanywhere . . . very distinctive the originals [. . .]”

Examiner: “Are they square . . . are they . . . ?”

MT: “Round”

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586 COCCHINI ET AL.

Examiner: “Thick or thin?”

MT: “ . . . pretty thin really, certainly not thick”

Examiner: “Are they red . . . ?”

MT: “No they are white . . . yes, [. . .]”

Examiner: “Would you like to show me one ofthese pills?”

MT: “Yes sure” [MT pulled out from his pocketan imaginary blister of pills and squeezed oneout onto the examiner’s hand adding “Just oneparacetamol?” For the remaining part of the con-versation the examiner held her right hand open inclear view of MT.]

Examiner: “OK” [. . .] Looking at the contentof her hand the examiner added: “ . . . and thisis the white pill that you have just taken? Thesame?”

MT: “Yes, exactly the same”

Examiner repeated: “Is it exactly the same?”

[MT nodded to confirm].

Examiner: “ . . . and if I take this pill will myheadache go away?”

MT: “It should do, yes”

Examiner (looking at her hand) added: “Youknow...I have a problem . . . I can’t see the pill inmy hand”

MT (looked very serious and concerned): “Youcan’t really see it?”

Examiner: “No, I can’t”

MT: “You can’t see it . . . oh . . . this is because itis not there, is it?”

Examiner: “So it’s not there?”

MT: “No it’s not”

Examiner: “Am I holding something?”

MT: “No” [. . .] “But I can give you a real one ifyou want” (giggling)

Examiner: “Yeah, is it here the real one?”

MT: “The real one is here” (again picking up animaginary pill dispenser from the same pocket).MT put on the table the imaginary pill dispenserand added “Here is the real one” and pretended toput a pill on the examiner’s hand.

Examiner: “Can I have also a glass of water?”

MT nodded and put an imaginary glass of wateron the table.

The examiner mimicked the action of picking upthe glass with her left hand and she held it in frontof MT, then the examiner added “So, I’m holdinga glass of water and a pill . . . ”

MT: “Yes, the paracetamol”

Examiner: “The real one . . . .this time?”

MT: “Yes, yes”

The examiner looked at her hands and added: “Ihave again a problem . . . . I can’t see them.”

MT (looking very perplexed): “You can’t see?”

Examiner: “No, I can’t see the glass...”

MT: “Oh gosh!”

Examiner: “What do you think?”

MT was visibly concerned and after some thinkingadded “It is not a question of lack of light, is it? . . .

The light is on, here . . . and it’s not dark”

Examiner: “Indeed”.

MT: “We can still use the torch (picking up withhis right hand an imaginary torch, then pointing itdown on the top of the examiner’s hands and mov-ing it left and right) . . . just to check if you can seethe light bouncing . . . ”

Examiner: “Yeah . . . but why do you think that Icannot see these things?” [looking at her hands]

MT: “ . . . it’s . . . it’s . . . because there’s nothingthere, is it?”

Examiner: “Is nothing there?”

MT: “Yeah”

Examiner: “This explains why I cannot see them.”

MT: “Yeah . . . it’s just pretending”

Examiner: “Ok, so were we just pretending?”

MT (looking a bit relieved): “Well . . . I think itlooks in that way, isn’t it? really . . . logically”

Examiner: “Yes, it looks so. But before, you actu-ally saw the pill in my hand?”

MT: “Well . . . it’s suggestion, isn’t it? I thought Idid, I wanted to, so I did . . . . but I don’t think Ican actually see it to be honest . . . because it’s notthere!” [. . .]

Examiner: “Does this happen frequently? . . . Tothink that things are there when they are actuallynot?”

MT: “Not often . . . fairly . . . rarely . . . when I’mvery tired [. . .]”

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PHANTABULATION 587

Finally, MT also showed a few instances of a phe-nomenon that looked like reduplicative paramnesiafor places. On one occasion, after a testing session,he welcomed the examiners into his hospital roombehaving as if it was his house. “This is my roomwhere I live...it is my mum’s house.” Once inside, heopened the door of an en-suite bathroom and added“Two beds, one here (indicating the WC) and onethere (indicating the basin).” Then, walking towardthe mirror as if to avoid bumping into the two beds,he pointed to the mirror and added “This is thewindow.” Going back to the bedroom, MT claimedthat it was his bedroom in the flat that his partnerhad decorated.

Recovery and follow-up

About 8 months after his brain lesion, MTshowed a dramatic reduction in the numberof episodes of Phantabulation. Three monthslater, these had ceased completely, and he wasdischarged.

The examiners visited MT one last time, at home,15 months after his acute brain lesion. He was eagerto converse with the examiners but was not muchinterested in completing formal tests, though, onrequest, he drew a clock from memory flawlessly.He appeared much better oriented to space andtime, committing only one error on the date ofthe month (anticipated by 1 day). He still had avisual deficit for the right eye and mentioned somecontinuing visual and memory difficulties. Someof his conversation clearly showed some degree ofretrograde and anterograde amnesia. He had diffi-culty remembering what had happened or what hehad eaten the day before, and he could rememberonly some of the people he had met at the hos-pital, and some related events, but quite vaguely.He did not recognize the two examiners, despitehaving seen one of them on a daily basis duringhis time on the ward and the other on severaloccasions.

During the conversation, which lasted a cou-ple of hours, he interacted normally with var-ious objects, smoking several cigarettes, drink-ing tea, and moving objects without any signof Phantabulation. His mother confirmed that hehad never shown Phantabulations since he left thehospital. When asked if he remembered havingimagined objects that were not present, he lookedsurprised and asked his mum if he really haddone so.

DISCUSSION

For about 8 months, MT showed a highlyunusual phenomenon, unique in our experience, inwhich he appeared to interact purposefully withobjects not physically present. These episodes of“Phantabulation” were quite frequent and vivid,could occur at any time of day, and were trig-gered either by MT’s urge to complete a task (e.g.,performing a psychometric test) or by less explicitneeds, such as desiring to hold a cigarette during aconversation.

MT could describe the imagined objects veryaccurately, providing rich sensory details toquestioning, mostly visual but sometimes alsosomatosensory. Phantabulations were emotionallyneutral and were always referred to contextuallyplausible objects. When challenged with clearlycontradictory information, MT tried to accountfor his Phantabulations with logical explanations,often confabulating. Therefore, MT seemed able toreach logical conclusions, though they were basedon incorrect premises. On repeated questioning,he would usually capitulate eventually, concludingor acknowledging that the objects must have been“pretended.” This suggests that the phenomenonwas not completely detached from monitoringof reality. Considering MT’s non-verbal com-munication, he was apparently unaware of theunreal nature of his perceptions while he wasexperiencing them. He typically looked puzzledwhen confronted with contradictory informationand quite relieved when he managed to providewhat he considered a plausible explanation.Such “explanations,” together with evidence ofreduplicative paramnesia, are unusual in patientssuffering from hallucinations, and they support thehypothesis of an important delusional componentof Phantabulations.

MT had memory deficits and presented with con-fabulatory tendencies. However, his confabulationswere unusual as, contrary to classic confabulations(e.g., Kopelman, 2010), they never considered auto-biographical or future thinking events. Rather, theyinvolved solely current events and seemed to pro-vide him with a means to rationalize his interactionswith imagined objects.

Phantabulations may appear to share some simi-larities with utilization behavior (Lhermitte, 1983).However, contrary to utilization behaviors (see e.g.,Boccardi, Della Sala, Motto, & Spinnler, 2002),Phantabulations were not triggered by environmen-tal cues but rather by endogenous drives. Moreover,

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unlike utilization behavior (e.g., Besnard et al.,2010), the actions characterizing Phantabulationepisodes were never socially inappropriate.

Despite some points of resemblance, MT’sbehavior also cannot be classed within any ofthe various types of hallucinations described inthe literature. Before brain damage, MT wasa heavy drinker and cannabis user. Withdrawalfrom these substances may cause brief pareidolichallucinations, whose content often consists of per-ceiving distorted animals or persons (Lilliputianhallucinations; Sims, 2003) and which are usuallyassociated with tremor, occasional loss of con-sciousness, and altered arousal with sleep disor-ders, such as insomnia and nightmares (Manford& Andermann, 1998). Phantabulations showednone of these features, and MT never reportedsleep problems. They also appeared quite dis-tinct from hallucinations associated with psychi-atric syndromes, which are predominantly audi-tory, with recurrent themes of high emotionalvalence, often delusional and triggered by anxi-ety (e.g., David, 2004; Pierre, 2010; Sims, 2003).Interaction with the “object” of the psychiatrichallucinations is highly unusual and very limited(Manford & Andermann, 1998; Sims, 2003), wheresuch interaction was a defining characteristic ofPhantabulation. Moreover, Phantabulations werealways contextually appropriate, such as holding apen to perform a drawing, which is not typical ofpsychiatric hallucinations.

Visual hallucinations following brain damage area central feature of Charles Bonnet syndrome.These hallucinations appear within the blind visualfield (e.g., Vaphiades, Celesia, & Brigell, 1996),especially under conditions of dim light or whenthe patients are somnolent (e.g., Kazui et al., 2009;Schultz, Needham, Taylor, Shindell, & Melzack,1996). In common with sufferers of Charles Bonnetsyndrome, MT showed a visual impairment, dueto damage to the visual pathway coupled withintact visual primary cortex (Ffytche, Howard,Brammer, Woodruff, & Williams, 1998). Moreover,Phantabulations occurred more frequently, thoughnot solely, in MT’s blind visual field. However,the content of hallucinations in Charles Bonnetsyndrome tends to be recurrent (e.g., Manford& Andermann, 1998), occasionally bizarre andamusing (Ffytche et al., 1998) but not purpose-ful. Such patients are well aware of the unrealnature of their hallucinations while they are expe-riencing them (Ffytche et al., 1998; Kazui et al.,2009; Lalla & Primeau, 1993; Schultz et al.,

1996; Teunisse, Cruysberg, Hoefnagels, Verbeek,& Zitman, 1996) and show very limited inter-action, if any, with them. For example, Kazuiet al.’s (2009) patient, claimed not to be ableto touch the cats “despite her efforts to do so”(p. 79). The purposeful, contextually appropri-ate interaction with the imagined objects there-fore distinguishes Phantabulations clearly fromthe hallucinations observed in Charles Bonnetsyndrome.

Some authors have suggested that a corti-cal release phenomenon may be responsible forhallucinations. Indeed, while perception of visualstimuli normally inhibits endogenous activation ofthe visual cortex, in the absence of exogenous infor-mation, the spare visual areas would suffer fromsensory deprivation, releasing these areas from thenormal regulatory system (Cogan, 1973) and lead-ing to the formation of hallucinations as in CharlesBonnet syndrome (Ffytche et al., 1998; Kazui et al.,2009; Manford & Andermann, 1998). However,the explanation for cortical release predicts a rela-tively “casual,” simple, and probably recurrent con-tent of hallucinations. On the contrary, MT’s phe-nomenological perceptions were apparently com-plex and tightly linked to current context and hisactual needs, more in line with a top-down pro-cess. That is, he “perceived” a toothbrush whenhe needed to brush his teeth, and he “perceived”a painkiller pill when he had headache. He neverreported contextually incongruous hallucinations.Unlike patients showing hallucinations, MT seemedto “reinterpret” reality according to specific needs.For example, as in reduplicative paramnesia, heseemed to “reduplicate” objects. However, vivid-ness of Phantabulations is crucial, as MT actuallyinteracted with the imaginary objects to a muchgreater extent than is observed in classical redu-plicative paramnesia. It is therefore important toexplain why MT “saw” in first place non-existentobjects and why he perceived exactly the objectsthat were functional to his goal. A possible expla-nation may be found in a combination of factorsalso involving visual imagery.

The role of visual imagery in false percep-tion is not new and other authors have suggestedthat “complex visual hallucinations [. . .] could beinitiated by visual imagery” (Wünderlich et al.,2000, p. 561; see also Goldenberg, Müllbacher, &Nowak, 1995). MT’s performance on the sourcemonitoring tests confirms his tendency to con-fuse imagined with real information, and his per-formance on the verbal continuous recognition

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PHANTABULATION 589

task suggests a difficulty in suppressing previousinformation.

MT’s visual imagery was well preserved in for-mal tests and he was clearly imagining in finedetail some of the phantom objects he interactedwith, and the phantom drawings he produced.Interestingly, Ffytche et al. (1998) observed thatthe releasing mechanism could also involve ven-tral extrastriate activity, and other authors observedadditional activation of frontal and parietal cor-tex, suggesting that extrastriate activity may bemodulated by frontal and parietal top-down mech-anisms that mediate “retrieval of object represen-tations from long-term memory and their mainte-nance through visual imagery” (Ishai, Ungerleider,& Haxby, 2000, p. 979). MT’s executive processesare compromized, as confirmed by his poor per-formance on some relevant tests (e.g., Brixtontest). Therefore, visual imagery may account forthe highly purposeful content of Phantabulations,which may have been enhanced by the corticalrelease mechanism and lack of inhibition due to thefrontal damage.

Phantabulations are characterized by the pur-poseful interaction with contextually appropriateimagined objects. We suggest that these episodes, inpatient MT, may depend on a combination of phe-nomena, whereby the effects of a top-down mecha-nism involving florid visual imagery is facilitated bycortical release due to frontal damage, resulting in aconfusion between real and imagined objects. Theseabnormal percepts are probably enhanced by anassociated malfunction of the fronto-parietal path-way, which fails to inhibit the imaginary processesand the evocation of their related actions.

Original manuscript received 24 October 2012Revised manuscript received 17 June 2013Revised manuscript accepted 1 July 2013

First published online 21 August 2013

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