衝動 (性格)

衝動粵拼cung1 dung6英文impulsivity形容詞impulsive)喺性格心理學上係一種特質(trait)。响廿一世紀初,性格心理學界對「衝動」嘅具體定義仲未有完全一致嘅共識;不過一般嚟講,話一個人衝動係指嗰個人做嘢唔諗後果[1][2],而衝動嘅人成日都會因為佢哋唔諗後果,做出一啲短期內得益但長遠嚟講搞到自己受損嘅行為[3][4]

「我都知吸毒第時可以好長手尾,不過總之家陣爽咗先啦。」
「哎吔,又試唔覺意隨手買咗柞唔等使嘅嘢返嚟。今個月又赤字喇。」

舉個例說明,想像家陣有個人俾人引佢吸毒,由佢嘅角度睇嘅話:佢揀吸毒可以為自己帶嚟短期嘅快感,但噉做長遠嚟講會有上癮等嘅重大負面後果;而相對嚟講,如果佢揀唔吸毒就會而家冇得享受快感,但噉做長遠就唔使承受吸毒引起嗰啲重大後果-揀唔吸毒嘅話,第時就會得到更加大嚿嘅快感;即係話喺成個過程裏面,個人要由短期嘅快感長遠嘅利益之間二揀一[註 1][4];如果話一個人衝動嘅程度高,通常係話佢傾向會揀短期快感多過揀長遠利益,而如果話一個人衝動嘅程度低,就通常係話佢傾向顧及長遠利益多啲[5][6]

衝動呢個概念喺精神醫學同相關領域上好受關注:衝動性格可以引致好多唔健康嘅行為,例如衝動嘅人更加易會走去吸毒同有第啲形式嘅物質濫用[6],又或者係會成日衝動買嘢搞到財政上有問題[7];另一方面,研究又表明咗衝動係好多種心理病嘅重要症狀之一,好似過度活躍症(ADHD)[8]躁鬱症(BPAD)[9]同埋好幾種嘅性格障礙[10]嘅患者都會有衝動得滯嘅情況。因為噉,理論性嘅心理學神經科學上都有重點研究衝動,會諗衝動行為要點樣量度,又或者係諗應該用咩精神科藥先至可以有效噉處理衝動相關問題[11],而呢啲研究係廿一世紀初精神健康知識嘅重要一環。

概念定義

睇埋:衝動性格特質動物行為學同埋認知心理學

要研究衝動,第一步係要定義「衝動」一詞。喺廿一世紀初嘅心理學上,定義「性格上嘅衝動」會用到以下呢啲概念[註 2]

延遲折扣

 
家陣俾一個人喺「即刻攞到一件蛋糕」同「一個禮拜後攞到嗮成個蛋糕」當中二揀一,佢會點樣揀呢?
內文:延遲折扣

延遲折扣(delay discounting)呢個概念可以攞嚟思考「衝動」:想像家陣擺隻大鼠喺個入面,籠入面有兩個掣,撳   掣會即刻得到一粒嘢食,而撳   掣會喺 5 分鐘之後得到一粒一樣嘅嘢食,兩個掣喺撳咗一嘢之後 5 分鐘之內唔會有反應,結果通常係,隻大鼠肚餓嗰陣會走去撳   掣,但會對   掣不聞不問;另一方面,如果更改兩個掣嘅結構,變成撳   掣會喺 5 分鐘之後得到一嚿大嚿啲嘅嘢食嘅話,隻大鼠就比較有可能會對   掣有興趣-於是學界有咗個諗法,主張喺隻大鼠心目中,一嚿嘢食嘅主觀價值會隨住「得到佢要等嘅時間」而下降,而一樣事物隨住「得到樣嘢要等嘅時間」嘅主觀價值下降就係所謂嘅延遲折扣(由延遲造成嘅折扣)。延遲折扣嘅現象喺等嘅多種動物身上都可以觀察得到[12][13]

根據廿一世紀初嘅雙曲線折扣(hyperbolic discounting)模型,一件事物嘅主觀價值會跟從以下呢條式[14]

 ,當中
  •  折扣因素(discount factor;指折扣之後淨低原本數值嘅幾多百分比,呢個數值愈細反映件嘢嘅主觀價值跌得愈勁),
  •   係延遲(要等幾耐先可以得到件事物),而
  •   呢個參數就主宰咗個個體嘅折扣程度,呢個參數大致反映咗個個體有幾衝動[14][15]

延遲折扣係衝動嘅重要一環:想像有個人,佢有個朋友喺度嘗試說服佢吸毒;佢有足夠嘅認知能力,知道啲毒品吸咗之後會喺短時間之內好興奮好過癮,但佢亦都知道,吸毒上癮長遠嚟講係有好負面嘅後果嘅(長期會令自己得到嘅快感總量大跌)-即係話佢要喺「短期嘅細嚿利益」同「長期嘅大嚿利益」兩個選擇當中二揀一,就好似延遲折扣實驗嘅情境噉。實證嘅心理學研究表明,人同人之間喺延遲折扣上有差異-有啲人會比較唔睇重長遠嘅利益(  數值比較大),令到佢哋主觀噉覺得長遠嘅大嚿利益冇咁有價值,即係比較傾向會為咗短期嘅快感而犧牲長期嘅利益,而衝動研究上一般認為,一個個體嘅   數值愈大,就表示佢愈衝動[16][17]

重要變數 1:性格衝動由一個個體喺延遲折扣當中嘅拆扣參數   反映;  數值愈大衝動程度就愈高。

抑制控制

 
「咦,綠燈喎,等我過馬路先...」
跟住喺下一刻,盞交通燈紅燈,個人就即刻跟住停低(抑制「過馬路」呢個行動)。
內文:抑制控制
睇埋:埃奧華賭錢遊戲

抑制控制(inhibitory control)係指一個個體「抑制就嚟要郁手做嘅行動」嘅能力:呢個概念可以用去-唔去(go/no go)嘅測試嚟諗;又想像家陣擺隻大鼠喺個籠入面,籠入面有個掣同一盞燈[18][19]

  • 每當盞燈閃綠色光(訊號go signal)嗰陣,隻大鼠就要喺 1 秒內去撳個掣,撳啱咗嘅話就有嘢食;而經驗顯示,隻大鼠好快就會學識一見到盞燈閃綠色光就去撳掣。
  • 跟住想像加一條新嘅規則,由而家開始,每次盞燈閃綠色光嗰陣,都有若干機率  )會係盞燈喺 0.2 秒之後閃紅色光(唔去訊號;no-go signal),如果出現咗唔去訊號,噉隻大鼠就要唔好去撳掣,而如果佢冇做到抑制自己撳掣嘅行動嘅話,就會受到懲罰,例如個籠會有電流通過電佢,令佢有嘅感覺;

每當隻大鼠見到去閃綠燈(去訊號)嗰陣,佢都會為咗想有嘢食而有股動力去撳掣(行動),而如果跟住出現紅燈(唔去訊號),佢就需要停低唔好做出「撳掣」呢一個舉動(抑制就嚟要郁手做嘅行動)。一隻動物-無論係大鼠定係人都好-喺去-唔去測試當中「對唔去訊號俾正確嘅反應嘅機率」( )就反映咗佢嘅抑制控制能力[18][20]

一般認為,衝動係同抑制控制成大致反比嘅:去-唔去測試嘅研究方法可以攞嚟喺人身上做[註 3];一個人抑制控制能力愈高,就反映佢嘅衝動程度愈低,反之亦然;如果話一個人衝動嘅話,就表示佢抑制控制能力低,成日都會一見到想要做嘅嘢就即刻郁手去做,明知噉做會有後果都係照做;例如一個因為衝動而暴飲暴食嘅人噉,佢往往都係一見到嘢食(去訊號)就會有股衝動走去食(行動),就算佢跟住就諗起「食得多得滯會搞到自己」嘅後果(唔去訊號),都照樣繼續食(抑制失敗)[21]。除咗暴飲暴食之外,抑制控制能力亦都同好多衝動相關嘅心理病有啦掕-例如係過度活躍症(ADHD)[22]爛賭[23]等嘅心理病嘅患者都傾向有抑制控制能力過低嘅情況。

重要變數 2:性格衝動由一個個體喺去-唔去測試當中嘅表現反映;  數值愈大衝動程度就愈低。

延遲滿足

 
棉花糖實驗:「小弟弟/小妹妹,我都知呢粒包咗朱古力棉花糖望落好好食。而家我行開 15 分鐘,如果你可以忍住唔食粒糖忍到我返嚟為止,我就送成大包噉嘅糖俾你。」
內文:延遲滿足
睇埋:棉花糖實驗

延遲滿足(delayed gratification)係另一個反映衝動嘅變數。延遲滿足反映一個個體「抗拒誘惑」嘅能力[24]

延遲滿足可以用棉花糖實驗(marshmallow experiment)嘅方式嚟思考:棉花糖實驗係一種常用於人類細路身上嘅心理實驗,成日俾人攞嚟研究衝動同埋過度活躍症等嘅課題;喺呢個實驗裏面[24][25]

  • 研究員會將一個細路帶入去一間實驗室入面,俾個細路喺張檯前面坐低,檯上面有一隻碟,碟上面擺咗粒望落好好食嘅棉花糖喺度;
  • 跟住個研究員會同個細路講,話自己要行開 15 分鐘,再同個細路(如實噉)話如果佢可以一路忍住唔去食粒糖,一路忍到個研究員返嚟為止嘅話,噉個研究員就會送一大包同一樣樣嘅糖(或者第樣個細路鍾意想要嘅嘢)俾佢;
  • 喺個研究員行開咗嗰 15 分鐘期間,個研究員嘅同事會一路監察住個細路,睇吓個細路可以抗拒「郁手去食粒綿花糖嘅慾望」抗拒到幾耐,最後會得出一個數值  -即係「個細路能夠忍到幾耐」。

延遲滿足可以想像成延遲折扣抑制控制嘅結合版本:當一個人(或者第啲動物)進入「要喺一嚿細嘅即時利益同大嘅延遲利益之間二揀一」(延遲折扣情境)噉嘅情況嗰陣,佢要响腦入面衡量嚿延遲利益嘅價值,而如果佢決定咗覺得延遲嗰嚿利益價值夠大,值得為咗呢嚿利益而放棄嚿細嘅即時利益,佢就要壓抑(抑制控制)自己想去郁手攞嚿即時利益嗰股衝動。事實係實證研究表明:一個細路喺棉花糖實驗嘅表現-以  量度-同佢延遲折扣嘅   同抑制控制表現有相當強嘅相關[26];而有過度活躍症嘅細路-已知佢哋係零舍衝動-冇一般嘅細路咁能夠忍住唔去食粒糖[27]

重要變數 3:性格衝動由一個個體喺棉花糖實驗(或者類似測試)當中嘅表現反映;  數值愈大衝動程度就愈低。

認知偏向

睇埋:雙重過程理論同埋啟發法

衝動呢個概念仲可以由認知嘅角度嚟諗。喺廿一世紀初嘅認知心理學上有所謂嘅雙重過程理論(dual-process theory),根據呢個理論,認知過程(大致上係指入面嘅資訊處理過程)可以分做兩大種-第一型過程(Type 1 process)同第二型過程(Type 2 process),呢兩種過程嘅對比如下[28][29][30]

第一型過程:
直覺
第二型過程:
理性
定義性嘅特徵 唔使用到工作記憶 要用到工作記憶
通常有嘅特徵
  • 快(可以即刻俾答案)
  • 可以同時處理大量資訊
  • 平行(可以同時做幾樣作業)
  • 意識
  • 易受認知偏誤左右
  • 自動化嘅
  • 智能嘅相關比較弱
  • 慢(要諗吓先俾到答案)
  • 淨係有得同時處理少量資訊
  • 串連(冇時同時做幾樣作業)
  • 有意識
  • 冇咁易受常見嘅認知偏誤左右
  • 受控嘅
  • 同智能嘅相關比較強
相關腦區[31]

杏仁核(amygdala)等

前額皮層(PFC)等

衝動俾人指係可以想像成一個人有幾依賴第一型過程:當一個人跟第一型過程行事嗰陣,佢嘅行為會傾向由一啲自動化同無意識嘅習慣主導,即係例如見到嘢食就習慣性噉去食、一發作就習慣性噉去點火食煙... 呀噉;第二型過程就唔同,會有能力响郁手之前思考吓嗰樣行動應唔應該做(例:「我有股動力去食嘢,但我知自己要減肥,所以都係唔食好啲」),所以會比較有能力抑制啲唔恰當嘅行為;於是有研究者就主張,一個人衝動程度高好多時都係因為佢太過依賴第一型過程嚟行事,而事實係實驗嘅研究表明咗,太過依賴第一型過程嚟行事同各種嘅上癮有正嘅相關[31][32]

重要變數 4:性格衝動由一個個體『有幾依賴第一型過程』反映;依賴第一型過程嘅程度愈高,衝動程度就愈高。

神經底質

睇埋:犒賞系統同埋快感中心

神經造影研究可知,同衝動有啦掕嘅腦區包括咗以下呢啲[33][34]

杏仁核

內文:杏仁核
睇埋:動機強度

杏仁核(amygdala)係個顳葉(temporal lobe)內部兩粒好似杏仁噉形嘅結構,功能上主管情緒,而且對情緒性記憶嘅產生不可或缺;例如實驗性嘅研究就發現,用微弱電流等嘅方法刺激杏仁核嘅某幾忽會搞到隻動物突然變得有攻擊性,而刺激杏仁核嘅另外幾忽又會令隻動物突然間馴嗮[35]

 
一個人腦由左面(左圖)同前面(右圖)望嘅立體圖解;紅色嗰兩粒就係左腦右腦杏仁核

杏仁核仲主宰咗動機強度(motivational salience)-動機強度係指一個個體嘅行為有幾趨近一件物體或者事件,包括咗擺幾多注意力落去件物體事件嗰度呀噉,大致上反映「隻動物有幾重視嗰件物體事件」,而杏仁核引起嘅情緒變化會強烈噉影響隻動物對一件物體事件嘅動機強度,例如一件犒賞引起嘅情緒反應愈勁,隻動物就愈會想要件犒賞,就愈會(例如)集中注意力落去件犒賞身上[36]

神經造影研究指,杏仁核敏感得滯傾向會搞到一隻動物衝動:杏仁核會响隻動物感知想要嘅嘢(例如嘢食)嗰陣啟動,尤其如果嗰樣想要嘅嘢係可以即刻得到嘅話,杏仁核活動會零舍勁[37];簡化噉講嘅話,無論人定第啲動物,都有「某啲個體嘅中側杏仁核特別敏感,容易一見想要嘅嘢就有強烈嘅活動」噉嘅情況,而呢啲個體亦都傾向會一見到想要嘅嘢(可以係毒品或者呀噉)就即刻將注意力集中嗮喺嗰樣嗰度或者變到好興奮,通常都會比較容易忍唔住即刻想郁手攞嗰樣嘢-比較衝動[33]

前額皮層

 
一個人左腦嘅 3D 圖解;紅色嗰忽就係前額皮層。
內文:前額皮層
睇埋:自控能力

前額皮層(prefrontal cortex,PFC)係大腦皮層哺乳類大腦最外面嗰浸神經組織)最近額頭嗰一橛,出嗮名專門幫手做一啲所謂嘅「高層」認知功能,例如係計劃決策呀噉;前額皮層會由底層啲嘅腦區(例如 VTA)嗰度接收由某啲神經傳遞素傳嘅訊號,又能夠向伏隔核(NAc;會對嘢食等嘅犒賞有反應嘅腦區)等嘅多個腦區傳訊號-「能夠向 NAc 傳訊號」就表示,前額皮層有可能對伏隔核等嘅犒賞結構作出一定程度嘅管控,而廿一世紀初嘅研究的確顯示,前額皮層會扮演啲噉嘅功能[33][38]

前額皮層嘅管控功能對衝動同自我控制嚟講好重要:

  • 有研究者試過一路用神經造影技術監察受試者嘅腦活動,一路要佢哋做延遲折扣決策,叫佢哋做若干次「喺一嚿細嘅短期得益同一嚿大嘅延遲得嗌之間二揀一」噉嘅決擇,發覺前額皮層某幾橛嘅活動同個體嘅  顯著相關,又同嚿延遲得益嘅量有正相關[39][40]
  • 簡化噉講,前額皮層嘅神經細胞運算每個選項嘅價值(睇埋效益),然後按每個選項嘅主觀價值嚟傳訊號去腦嘅其餘部份,調控嗰啲部份嘅活動,例如家陣前額皮層決定咗「短期快感嗰個選項冇長期利益嗰個咁好」,佢就會傳訊號阻止杏仁核產生「會引導個人去追求短期快感」嘅情緒變化[33]

因為噉,前額皮層嘅功能對一個人嘅自控能力有深遠嘅影響[41],而前額皮層出現病變往往會搞到個病人喺自控能力上出現異常[42]

第啲腦區

... 等等。

精神醫學研究

 
1915 年法國一幅海報呼籲人唔好酗酒-圖入面個男人掛住飲酒,而佢老婆同對仔女喺度求佢放低支酒。
睇埋:衝動控制障礙同埋黑暗三角特質

衝動呢個概念喺精神醫學上相當受關注,因為過高嘅衝動性同好多種嘅心理病都有啦掕:

  • 過度活躍症(ADHD):ADHD 係一種心理病,特徵係個人專注力唔夠而且鍾意係噉郁(坐唔定);有 ADHD 嘅細路好多時因為佢哋喺學校難以集中精神聽書或者做功課,而喺學習上遇到障礙,所以呢種病相當受心理學界關注;高嘅衝動性係 ADHD 嘅其中一個重要症狀[43],而有 ADHD 嘅細路喺棉花糖實驗當中嘅表現明顯差過一般嘅細路[27]
  • 躁鬱症(bipolar disorder,BPAD):BPAD 嘅患者特徵係會一時情緒低落一時又會情緒好高漲,情緒低落嗰陣成個人會冇嗮心機做嘢,而喺高漲階段嗰陣個人通常會變到異常咁衝動,容易因此做出啲唔理性嘅行為[9]
  • 物質濫用(substance abuse):物質濫用泛指一個人係噉勁吸一啲對身體有害(但好多時能夠帶嚟短期快感)嘅物質,包括咗酗酒吸毒等嘅行為-呢啲物質好多時都係長遠嚟講會傷身,甚至搞到個人上癮嘅,所以物質濫用嘅問題相當受關注;研究指,衝動嘅人比較容易有物質濫用嘅行為[44][45]
  • 暴飲暴食:暴飲暴食係指一個人响短時間之內勁喺度食嘢,好多時會搞到自己體重失控並且影響健康;暴飲暴食好多時都係源於個人嘅自控能力失靈,搞到個患者喺短時間內衝動程度大升,從而忍唔住走去勁搵啲令自己爽嘅嘢嘢食[21],而研究指,性格衝動嘅人比較容易出現暴飲暴食嘅行為[46]
  • 衝動買嘢:衝動買嘢係指個人成日一見到想要嘅嘢就買,而且買起上嚟唔諗後果(即係例如就算碌爆咗張信用咭都照買),容易會搞到個人喺財政上出現問題[47];有一部份嘅市場學工作者會專登靠引消費者衝動買嘢嚟圖利[48]
  • 心理病態(psychopathy):心理病態係一種性格上嘅問題,涉及個人唔識-心理學研究發現,一般人喺見到自己以外嘅人或者驚嗰陣,都會或多或少噉出現驚嘅反應(同理心),所以唔會想做出令其他人痛或者驚嘅行為;相比之下,心理病態嘅人缺少咗呢種反應-佢哋咩都唔驚,就算明知自己做緊嘅嘢(例如係操縱人、攻擊人甚至殺人)會令其他人受苦或者驚,佢哋都唔會有咩感覺;呢啲人亦都傾向因為唔識要「驚有後果」而有衝動嘅行為[49]

... 等等。

相關性格測驗

廿一世紀初嘅心理學精神醫學都會用一啲性格測驗(指通過心理測量核實過嘅量度性格用架生)嚟量度一個人有幾衝動。比較多人用嘅衝動性格測驗有以下呢啲:

問題數量[註 4] 問題類型
巴拉特衝動量表[50][51]
(Barratt Impulsiveness Scale,BIS)
30 條,分 3 個子量表 6 個因素 每條 1-4 分,分數反映一樣衝動相關行為發生得有幾密。
艾森克衝動量表[52][53]
(Eysenck Impulsiveness Scale)
54 條 每條都反映一樣衝動相關行為,以 Yes/No 噉嘅形式答。
迪卡文衝動清單[54][55]
(Dickman Impulsivity Inventory)
63 條,當中 23 條係虛問題
淨低嗰 40 條成 2 個因素。
每條都反映一樣衝動相關行為,以 True/False 噉嘅形式答。
行為抑制系統 / 行為啟動系統[註 5][56]
(Behavioral Inhibition System / Behavioral Activation System)
24 條,成 2 個因素 李卡特量表 1-4 分

註釋

  1. 詳情可以睇延遲折扣
  2. 技術性啲噉講,性格上嘅衝動係一個複合嘅心理建構,由多個變數反映。可以睇吓因素分析嘅嘢。
  3. 因為道德嘅問題,做喺人身上嘅研究正路唔會用引起嘅或者,而係會用人道啲嘅嘢做懲罰,例如「失敗咗就會搞到參與實驗得到嘅獎金減少」呀噉。
  4. 以最新版本作準
  5. 睇埋強化敏感度理論(RST)。喺 RST 當中,衝動可以局部噉視為「犒賞系統敏感得滯」。

睇埋

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