郝亞楠 宋勃東 王 巖 張 欽 郎 越

(首都師范大學心理學系, 北京市“學習與認知”重點實驗室, 北京 100037)

詩人拜倫曾說過, “悲觀的人雖生猶死, 樂觀的人永生不老”。積極心理學之父Martin Seligman也曾在他的暢銷書《活出最樂觀的自己》中談到,樂觀帶給人們大量的好處(洪蘭譯, Seligman,2010/1991), 可以體現(xiàn)在身心健康, 社會適應等諸多方面。這與大量學者通過實證研究考察樂觀對個體身體、心理和行為等方面影響的結果相一致。比如, 樂觀與身體健康(Hingle et al., 2014;Warner, Schwarzer, Schüz, Wurm, & Tesch-R?mer,2012)、幸福感(Solberg Nes, Evans, & Segerstrom,2009; Ammirati, Lamis, Campos, & Farber, 2015)、生活質量(Wrosch & Scheier, 2003; Zaslavsky et al.,2015)和工作滿意度(Kwok, Cheng, & Wong, 2015)等方面的提高存在顯著正相關。樂觀還與抗壓能力的增強(Jobin, Wrosch, & Scheier, 2014; Taylor,Larsen-Rife, Conger, Widaman, & Cutrona, 2010),抑郁癥狀的緩解(Hirsch, Nsamenang, Chang, &Kaslow, 2014)、創(chuàng)傷后應激障礙綜合征的減少(Gil& Weinberg, 2015), 以及創(chuàng)傷后的成長(Shand,Cowlishaw, Brooker, Burney, & Ricciardelli, 2015)等存在顯著正相關。不過, 樂觀的前期研究大都集中在它與其他主題的關系方面, 主要描述樂觀者的行為表現(xiàn)。但是有關樂觀心理機制探討的研究較少, 僅有Aspinwal, Richter和Hoffman (2001)提出的樂觀信念的適應功能(the adaptiveness of optimistic beliefs), 即樂觀的信念有助于個體靈活地分配認知資源, 從而更好地追求目標。但是該理論的后續(xù)研究很少。而近年, 隨著積極心理學的興起, 越來越多的研究者開始深入探討樂觀影響個體行為的內在心理機制, 這對于解釋樂觀的發(fā)生具有重要的啟示意義。

1 氣質性樂觀的界定

1.1 氣質性樂觀的定義

人格維度的樂觀和悲觀廣泛存在于大眾的智慧中, 而將樂觀作為一種人格特質的研究, 可追溯到30年前樂觀問卷——生活定向測驗(the Life Orientation Test, 簡稱 LOT) ——的誕生(Scheier& Carver, 1985)。在該研究中, Scheier和 Carver界定了氣質性樂觀(dispositional optimism)即一種對未來的總體的積極期待。這一定義提出的依據(jù)是動機的自我調節(jié)理論——期待?價值理論(Scheier & Carver, 1992)。該理論強調期待在行為調節(jié)中的關鍵作用, 當個體對目標持有積極期待時, 他們會采取趨近行為不斷縮短自己與目標的距離直至實現(xiàn)目標; 當個體對目標持有消極期待時, 他們會采取回避行為并放棄目標(Scheier &Carver, 1985, 1992), 這就是樂觀(optimism)和悲觀(pessimism)。樂觀既是一種穩(wěn)定的人格特質,又是一種認知結構, 其核心是期待。它表現(xiàn)為期待未來有很多好事情的發(fā)生(Scheier & Carver,1992; Carver & Scheier, 2014)。因此, 在面對困難時, 氣質性樂觀者傾向于堅信自己的目標能夠實現(xiàn), 受趨近動機調節(jié)和支配; 氣質性悲觀者則傾向于放棄目標, 受回避動機調節(jié)和支配(De Pascalis, Cozzuto, Caprara, & Alessandri, 2013;Rygula, Golebiowska, Kregiel, Kubik, & Popik,2015)。另外, Peterson和Seligman (2004)還將樂觀作為24項性格優(yōu)勢之一, 認為樂觀與希望、未來意識(future-mindedness)及未來定向(future orientation)一起代表了指向未來的認知、情緒與動機心理層面的積極特質。

氣質性樂觀的常用測量工具是生活定向測驗(LOT) (Scheier & Carver, 1985), 它于1994年得到修訂(LOT-R)。該測驗(LOT-R)采取自我報告法,共10個題目, 包括6個正式題目和4個附加題目,得分越高代表越樂觀。它測量了樂觀和悲觀兩個維度, 具有較高的信效度(Scheier, Carver, & Bridges,1994; Steca, Monzani, Greco, Chiesi, & Primi, 2015;溫娟娟, 2012), 而且被翻譯修訂成如漢語(溫娟娟,2012), 葡萄牙語(Laranjeira, 2008), 德語(Glaesmer,Hoyer, Klotsche, & Herzberg, 2008), 希伯來語(Benyamini & Raz, 2007)等多種語言, 是目前樂觀研究中使用最多的問卷。

當前, 盡管學者對樂觀概念的界定有很多種,如樂觀的解釋風格(洪蘭譯, Seligman, 2010/1991)、學業(yè)樂觀(Beard, Hoy, & Woolfolk Hoy, 2010;Sezgin & Erdogan, 2015)等等, 但是因為LOT-R問卷的廣泛應用, 使得其所測量的氣質性樂觀成為目前樂觀研究中最常用的界定方法。本文中的樂觀專指氣質性樂觀。

1.2 樂觀與希望的區(qū)分

為了進一步明確樂觀概念的界定, 我們將其與心理學中最相近的概念——希望——進行比較。Snyder等人(1991), Snyder, Feldman, Taylor,Schroeder和 Adams (2000)將希望(hope)定義為一種積極的動機性狀態(tài), 這種狀態(tài)是以指向目標的動力和達到目標的路徑的交互作用為基礎形成的(引劉孟超, 黃希庭, 2013), 也就是說希望是動機和方法的交互作用。樂觀和希望均是一種指向未來的人格特質。而且, 一些研究者用希望和樂觀的測量工具(AHS/HS vs. LOT-R)對兩者的關系進行實證研究, 發(fā)現(xiàn)兩者之間存在顯著正相關(Rajandram et al., 2011; Rand, 2009)。

雖然樂觀和希望存在共同點, 但它們并非同一概念。從定義來說, 樂觀更強調達到目標的動力的重要性, 即對未來的積極期待會促使人們行動, 但并未明確說明如何行動。而希望則將動力和路線放到了同等重要的位置(Snyder et al., 2000;Snyder, 2002)。從實證研究來看, 有研究者對1996至 2012年發(fā)表的希望和樂觀的文獻進行元分析,發(fā)現(xiàn)樂觀與某些變量諸如自尊或正性負性情緒等的相關顯著大于希望, 而希望與壓力、幸福感的相關顯著大于樂觀(Alarcon, Bowling, & Khazon,2013)。還有研究發(fā)現(xiàn), 在預測應對策略如積極重評的使用中, 樂觀的影響比希望大。反之, 在預測自我效能感時, 希望的影響顯著大于樂觀。此外,該研究還發(fā)現(xiàn)相對于希望的目標, 樂觀的目標更為寬泛(Bryant & Cvengros, 2004)?？梢钥闯? 樂觀與希望是有一定聯(lián)系但卻不同的兩個概念。

2 樂觀者的正性偏向

樂觀者總是在每一個困難中看到機會, 悲觀者總是在每一個機會中看到困難。溫斯頓?丘吉爾的這句名言, 是樂觀者具有正性偏向的最好闡述。研究也發(fā)現(xiàn), 活得開心幸福的人似乎帶著玫瑰色的眼鏡, 更愿意對積極刺激多加注意(Raila,Scholl, & Gruber, 2015)。從樂觀的定義來看, 樂觀者持有積極期待并且擁有趨近動機。而他們所具有的這一正性偏向不僅體現(xiàn)在期待和動機方面,還體現(xiàn)在注意、知覺、記憶、解釋風格、應對策略的選擇及情緒方面。這些既是樂觀者的行為表現(xiàn), 也是樂觀者的心理反應。

2.1 樂觀者對正性信息的注意偏向

注意偏向(attentional bias)是指相對中性刺激,個體對情緒刺激表現(xiàn)出不同的注意分配(Cisler &Koster, 2010)。樂觀者表現(xiàn)出對正性信息的注意偏向。Segerstrom (2001)要求被試判斷正、負性情緒詞、工具詞匯(控制條件)的書寫顏色, 發(fā)現(xiàn)樂觀者判斷正性情緒詞產(chǎn)生的Stroop效應大于負性情緒詞; 悲觀者僅在判斷負性情緒詞時產(chǎn)生Stroop效應, 判斷正性情緒詞產(chǎn)生的 Stroop效應不顯著。這說明, 詞的情緒性信息有效地干擾了不同樂觀程度被試對詞顏色的命名, 樂觀者產(chǎn)生了對正性情緒詞的注意偏向, 悲觀者則對負性情緒詞產(chǎn)生了注意偏向。同樣采用情緒 Stroop范式, 另有研究得出了相似的結果即樂觀者命名正性情緒詞顏色的時間顯著長于中性詞(Karademas, Kafetsios,& Sideridis, 2007)。同時, 樂觀者對負性信息的注意會減少。比如, Isaacowitz (2005)運用眼動追蹤技術考察樂觀者的注意偏向, 實驗要求被試觀察皮膚癌圖片, 結果表明與悲觀者相比, 樂觀者會選擇性地忽視負性信息, 這從另一側面體現(xiàn)了樂觀者的正性偏向。

2.2 樂觀者對正性信息的知覺偏向

知覺偏向(bias in perception)是指由于知覺主客體的特殊性以及一些外界環(huán)境因素的作用, 人在知覺過程中會產(chǎn)生一些與客觀現(xiàn)實不相符合的知覺結論(周曉虹, 1997)。樂觀者表現(xiàn)出對正性信息的知覺偏向。例如在遭遇相同困難時, 樂觀者報告獲得的社會支持高于悲觀者(Srivastava,McGonigal, Richards, Butler, & Gross, 2006;Wimberly, Carver, & Antoni, 2008)。而且在控制了社會支持的實際給予量后, 他們知覺到的依然較高 (Vollmann, Antoniw, Hartung, & Renner, 2011)。另外, 樂觀者在追求目標過程中報告獲得的進步要比悲觀者多 (Monzani et al, 2015)。相應地, 樂觀者知覺到負性信息就會減少。如面對同樣的負性事件, 樂觀者知覺到的壓力強度比悲觀者小(Jobin et al., 2014)。同樣, 相對悲觀者, 樂觀者知覺到的疼痛較輕(Geers, Wellman, Helfer, Fowler,& France, 2008; Hood, Pulvers, Carillo, Merchant,& Thomas, 2012)且持續(xù)時間也較短(Goodin,Kronfli, et al., 2013)。

2.3 樂觀者對正性信息的記憶偏向

記憶偏向(memory bias)指在控制了一般記憶能力后, 某種人格特質差異對某一特殊類型經(jīng)驗的回憶或再認有更好或更壞的傾向(引楊慧, 吳明證, 劉永芳, Li, 2012)。樂觀者表現(xiàn)出對正性信息的記憶偏向, 也就是說, 樂觀者更容易回憶起好的、正性的或有利于自己的內容。例如在玩撲克牌二十一點游戲時, 盡管成功的概率是隨機的,但是樂觀者一周后回憶贏錢的次數(shù)顯著多于悲觀者。換句話說, 樂觀者回憶出的正性信息比悲觀者多(Gibson & Sanbonmatsu, 2004)。還有研究要求被試瀏覽甲狀腺機能亢進相關的負性、中性及正性信息后進行自由回憶, 發(fā)現(xiàn)氣質性樂觀分數(shù)越高的被試回憶出正性信息的數(shù)量越多(Luo,2008)。同樣采用自由回憶的方式, 另有研究也發(fā)現(xiàn), 樂觀者回憶出積極詞匯的數(shù)量多于悲觀者(李燚, 2011)。

2.4 樂觀者具有積極解釋風格

解釋風格是一種認知性人格變量, 是人們對發(fā)生在自己身上不好事件的原因進行解釋時的習慣性態(tài)度(Peterson & Seligman, 1984)。氣質性樂觀者表現(xiàn)出積極的解釋風格即他們會將壞事情歸因為不穩(wěn)定的、特定的、外在的。Peterson (2000)曾提出大樂觀(氣質性樂觀)和小樂觀(樂觀的解釋風格)的概念, 并指出兩者相關的必然性。國內溫娟娟、鄭雪和張靈(2007)也認為樂觀是一種人格特質, 表現(xiàn)為一種積極的解釋風格。而且, 從理論上來說, 氣質性樂觀作為一種人格特質, 可能會影響人們的解釋風格(Rusting & Larsen, 1998), 即樂觀者在面對挫折時傾向于采取積極的解釋風格。從實證研究來說, 已有研究也發(fā)現(xiàn)氣質性樂觀和樂觀的解釋風格存在顯著正相關(溫娟娟, 鄭雪,2011; 祁珍華, 陳瑨, 江虹, 張紅靜, 2012; Zhang et al., 2014)。

不同的解釋風格可能是造成樂觀者和悲觀者行為結果差異的重要原因。如在追求成功方面,具有樂觀解釋風格的人在遇到困難時更容易繼續(xù)堅持, 這不僅體現(xiàn)在保險銷售方面(Seligman &Schulman, 1986), 還表現(xiàn)在軍事院校的訓練(Schulman, Castellon, & Seligman, 1989)或者團體運動方面(Carron, Shapcott, & Martin, 2014); 在學業(yè)方面, 采取樂觀解釋風格的學生的學業(yè)成績高于那些持有悲觀解釋風格的學生(Maleva, Westcott,McKellop, McLaughlin, & Widman, 2014; Peterson& Barrett, 1987)。而在其他方面諸如面對負性事件時, 持有樂觀解釋風格的學生的自殺意圖也少于悲觀的學生(Hirsch & Rabon, 2015)。

2.5 樂觀者選擇積極應對策略

應對策略是指個體面對不同的應激事件時所采取的認知和行為方式(Lazarus & Folkman,1984)。它和上述解釋風格既有區(qū)別又有聯(lián)系, 解釋風格是對人們行為的原因進行歸因, 而應對策略是個體對壓力性事件或情境的威脅性進行評估并作出相應的行為反應。解釋風格會影響人們對事件的應對策略, 對事件的積極解釋有利于個體采取積極應對策略, 對事件的消極解釋則有利于個體采取消極的應對策略(Sanjuan & Magallares,2015)。樂觀者持有積極解釋風格, 面對壓力事件傾向于采取積極應對策略。已有研究發(fā)現(xiàn)樂觀與積極應對策略的選擇存在顯著正相關(Chang &Chan, 2015; Goodin, Glover, et al., 2013; Goodarzi,Shokri, & Sharifi, 2015; Lee & Mason, 2013; Perera& McIlveen, 2014)。另外, Carver等人(1993)對乳腺癌患者進行追蹤研究也發(fā)現(xiàn), 樂觀者多采取事先計劃、積極重塑及幽默等積極應對策略; 反之,悲觀者則是采取否定事實、抑制抵觸情緒及放棄努力等消極應對策略。

積極應對策略的選擇是使樂觀者獲得更多益處的重要原因。有研究發(fā)現(xiàn)積極應對策略的應用是使樂觀者比悲觀者更易適應壓力的中介變量(Büyüka?ik-?olak, Gündo?du-Aktürk, & Bozo, 2012;Taylor et al., 2010, 2012), 也是減輕疼痛 (Hood et al., 2012; Wright et al., 2011)的中介變量, 還是學生運動員對學業(yè)和運動都感到較高滿意的原因(Gaudreau, Gunnell, Hoar, Thompson, & Lelièvre,2015)。

樂觀者為什么會采取積極應對策略？除了與解釋風格有關之外, 還可能與動機有關。有研究指出自我決定動機在樂觀和積極應對策略關系中起中介作用。換言之, 與低樂觀水平的學生相比,高樂觀水平的學生在參與活動時更易被自我決定動機驅使, 進而采取積極的應對策略(Thompson& Gaudreau, 2008)。

2.6 樂觀者體驗較多積極情緒

樂觀可能使人們長期處于一種積極的心境即積極的情緒狀態(tài)。樂觀者相信未來會發(fā)生很多好事情, 而這些好事情會使人們產(chǎn)生積極情緒(Strümpfer, 2006)。而且, 樂觀者會不斷為預期目標的實現(xiàn)而努力, 他們在不斷趨近目標的過程中也會體驗到較多的積極情緒(Carver & Scheier,2001; Ilies & Judge, 2005)。大量實證研究也發(fā)現(xiàn)樂觀與積極情緒存在顯著正相關(Cristea et al.,2011; Lench, 2011; Penedo et al., 2003; Segerstrom,Taylor, Kemeny, & Fahey, 1998)。還有研究發(fā)現(xiàn),作為一種樂觀干預的樂觀訓練既提高了樂觀水平也提高了被試的積極情緒體驗(Hanssen, Peters,Vlaeyen, Meevissen, & Vancleef, 2013; Peters, Flink,Boersma, & Linton, 2010)。

同時, 樂觀者體驗到的消極情緒會少于悲觀者。比如樂觀者觀看悲傷情節(jié)時產(chǎn)生的負面認知少于悲觀者(McHale, Clark, & Tramonte, 2015)。樂觀者面對心愛之人死亡時所產(chǎn)生的痛苦體驗也比悲觀者少(Boelen, 2015)。此外, 還有研究發(fā)現(xiàn)樂觀與焦慮及抑郁情緒呈顯著負相關(李恒芬, 曹素霞, 張勇, 2006; Johnson & Endler, 2002)。

2.7 小結

樂觀能夠給個體帶來諸多好處, 可能是因為樂觀者具有正性偏向。這一偏向主要表現(xiàn)在注意、知覺、記憶、解釋風格、應對策略的選擇、情緒、期待與動機方面。其中, 期待是樂觀的核心結構,而樂觀者持有積極期待可能是他們表現(xiàn)出正性偏向的基礎。期待會影響人們對信息的選擇加工(Iida, Nakao, & Ohira, 2012; Summerfield & Egner,2009)。同理, 積極期待會使樂觀者在認知過程中表現(xiàn)出正性偏向。與消極期待和無期待相比, 積極期待會使人更傾向于選擇加工正性信息(McNulty & Karney, 2004; Helfe, Elhai & Geers,2015)。而樂觀者在認知過程中表現(xiàn)出的正性偏向會使他們在面對負性或壓力事件時, 更傾向于采取樂觀的解釋風格和積極的應對策略。同時, 積極期待也會使樂觀者產(chǎn)生趨近動機并且誘發(fā)積極情緒(Scheier & Carver, 1985, 1992)。

樂觀者具有正性偏向是樂觀者的心理機制,但是它并不具有唯一性。另外, 這一偏向可能受其他因素的影響。當所呈現(xiàn)的信息具有自我相關性時, 樂觀者在認知過程中并未表現(xiàn)出正性偏向。如有研究發(fā)現(xiàn), 面對自我相關的正性信息, 樂觀者和悲觀者投入的注意資源并無顯著差異。而對于自我相關的負性信息, 樂觀者卻比悲觀者投入更多的注意資源(Aspinwall & Brunhart, 1996)。還有研究發(fā)現(xiàn), 相對于悲觀者, 樂觀者能回憶出更多的自我相關信息, 但是這與信息的效價無關(Abele & Gendolla, 2007)。這或許是因為與自我無關信息相比, 自我相關信息具有更重要的意義,所以樂觀者對這些信息進行精細加工以便采取積極主動的應對策略。

3 樂觀者正性偏向的神經(jīng)生理機制

通過上面的論述, 我們了解到樂觀者比悲觀者關注更多的正性信息并表現(xiàn)出正性偏向。而究其神經(jīng)機制可能與前扣帶回喙部(rostral anterior cingulate cortex, rACC)、前額葉皮質(prefrontal cortex)的激活水平相關。在上述這些神經(jīng)機制方面, 樂觀者和悲觀者表現(xiàn)出顯著的差異。

3.1 前扣帶回喙部

前扣帶回喙部位于前額葉皮質的吻側, 與傳遞情緒與動機信息的腦區(qū)如杏仁核有緊密聯(lián)系(Vogt & Pandya, 1987)。近年, 有研究發(fā)現(xiàn)與悲觀者相比, 樂觀者前扣帶回喙部的激活水平會增強(Sharot, Riccardi, Raio, & Phelps, 2007)。

Sharot等人(2007)的腦成像研究(functional Magnetic Resonance Imaging, fMRI)發(fā)現(xiàn), 前扣帶回喙部的BOLD (blood oxygenation level dependent)信號差值(想象未來積極事件?想象未來消極事件)與樂觀分數(shù)存在顯著正相關。也就是說, 樂觀分數(shù)越高, BOLD的信號差值越大, 即前扣帶回喙部的激活水平在想象未來積極事件時越高, 在想象未來消極事件時越低。這說明隨著樂觀分數(shù)的升高, 前扣帶回喙部的激活在想象未來積極事件時會增強, 這一增強反映了個體的自我調節(jié), 即對正性信息產(chǎn)生注意與警覺偏向。而已有研究發(fā)現(xiàn),前扣帶回喙部激活的增強與正性信息的加工相關。例如, 有研究采用 fMRI考察時間估計任務中正性反饋與負性反饋腦區(qū)激活水平的差異, 發(fā)現(xiàn)正性反饋時前扣帶回喙部的激活水平顯著高于負性反饋(Nieuwenhuis, Slagter, Von Geusau, Heslenfeld,& Holroyd, 2005)。另外, 在臨床研究方面, 前扣帶回喙部的高激活被認為是抗抑郁治療效果的指標, 即這一激活的增強表示抑郁癥患者癥狀好轉,比如他們更容易注意正性信息(Hunter, Korb,Cook, & Leuchter, 2013)。這從反面體現(xiàn)了前扣帶回喙部激活水平的增強在正性信息加工中的重要作用。

總之, 隨著樂觀分數(shù)的升高, 前扣帶回喙部的激活水平也會增強, 而這一區(qū)域激活水平的增強與正性信息的加工相關, 因此, 前扣帶回喙部激活的增強可能是樂觀者對正性信息表現(xiàn)出偏向的原因。

3.2 前額葉皮質

前額葉皮質負責高級運動的控制、計劃和執(zhí)行。它的解剖結構包括背側前額葉、扣帶前回、內側額葉及眶額皮層(周曉琳, 高定國等譯,Gazzaniga, Ivry, & Mangun, 2011/2009)。樂觀者正性偏向的神經(jīng)基礎可能涉及前額葉皮質(Bangen et al., 2014; De Pascalis et al., 2013)。

樂觀者左側額上回(left-superior frontal gyrus)的激活會增強。有研究通過腦電圖(EEG)記錄靜息狀態(tài) α波的激活, 發(fā)現(xiàn)樂觀與左側額上回的激活存在顯著正相關, 與右側扣帶回后部(the rightposterior cingulate cortex)的激活存在顯著負相關。作者認為樂觀與這兩個區(qū)域的相關不僅反映了他們對趨近與獎勵的敏感性, 還反映了樂觀者對能夠獲得獎賞的期待。而左側額葉激活的增強可能是導致高樂觀的原因(De Pascalis et al., 2013)。

除了左側額上回外, 前額葉腹內側皮層(ventral medial prefrontal cortex)、前額葉背內側皮層(dorsal medial prefrontal cortex)以及額下回(inferior frontal gyrus) 的激活水平也與樂觀相關。這些腦區(qū)激活的降低可能與樂觀者對負性信息的不敏感有關。有研究發(fā)現(xiàn), 在加工負性信息的過程中, 這些腦區(qū)的激活會隨著樂觀分數(shù)的提高而下降(Bangen et al., 2014)。作者認為這是因為樂觀降低了負性信息的凸顯性。而已有研究發(fā)現(xiàn)上述腦區(qū)激活的增強與抑郁癥患者、焦慮癥患者亦或創(chuàng)傷后應激障礙患者對負性刺激的加工增強有關(Mcclure et al., 2007; Morey, Petty, Cooper, LaBar,& McCarthy, 2008; Strawn et al., 2012)。例如, 相對于中性刺激, 創(chuàng)傷性綜合癥患者在加工負性信息過程中額下回的激活水平會增強(Morey et al.,2008)。這從反面證明了上述腦區(qū)激活的下降與個體對負性信息加工的減弱相關。也就是說, 前額葉腹內側皮層、前額葉背內側皮層以及額下回激活的降低與樂觀者對負性信息的不敏感有關。

3.3 小結

總之, 樂觀者表現(xiàn)出正性信息偏向與前扣帶回喙部、前額葉皮質的激活水平變化有關。這些腦區(qū)激活的變化與情緒信息加工相關, 可能反映了正性信息的凸顯性的提高以及負性信息的凸顯性的降低, 進而導致樂觀者表現(xiàn)出正性偏向。不過, 上述研究主要考察的是樂觀者在注意、情緒及期待方面表現(xiàn)出正性偏向的神經(jīng)生理機制。前文所提到的一些腦區(qū)如前扣帶回喙部、前額葉皮質等均是與注意、認知控制、情緒調節(jié)亦或期待相關的腦結構(Henseler, Krüger, Dechent, &Gruber, 2011)。而且, 研究中所用的實驗范式也是用來考察注意、情緒調節(jié)或期待, 比如表情匹配任務或想象未來積極或消極事件(Hariri, Bookheimer,& Mazziotta, 2000)。目前, 尚未有研究考察樂觀者在其他方面, 如知覺、記憶、解釋風格及動機等等, 表現(xiàn)出正性偏向的神經(jīng)生理機制。

為什么樂觀者和悲觀者前扣帶回喙部和前額葉皮質的激活水平會不同？這可能與遺傳有關。大量雙生子研究發(fā)現(xiàn)樂觀的遺傳度大約為30%(Caprara et al., 2009; Mosing, Zietsch, Shekar,Wright, & Martin, 2009; Mosing, Pedersen, Martin,& Wright, 2010; Plomin et al., 1992)。如 Mosing等人(2009)以3053對50歲至94歲的雙生子為研究對象發(fā)現(xiàn)樂觀的遺傳度為36%。同年, Caprara等人以428對23歲至24歲的雙生子為研究對象發(fā)現(xiàn)樂觀的遺傳度為 28%。近年, 學者還開始考察是否存在特定的基因成分直接影響樂觀和悲觀,但是結果并不一致。如 Saphire-Bernstein, Way,Kim, Sherman和Taylor (2011)的研究發(fā)現(xiàn)催產(chǎn)素受體(OXTR)基因的rs53576 GG型可能是樂觀的生物學基礎, 因為相對于rs53576 AA等位基因攜帶者, GG基因攜帶者的樂觀水平較高。但是, 另一項對美國 1229名女性的研究發(fā)現(xiàn)上述兩組基因攜帶者的樂觀分數(shù)并無顯著差異(Cornelis et al.,2012)。 Strohmaier等人則(2013)發(fā)現(xiàn), 男性鈣離子通道基因(CACNA1)中的rs1006737 AA等位基因攜帶者的樂觀水平較低?？傊? 樂觀和悲觀的差異部分源于遺傳, 而未來研究還需深入考察是否存在特定的基因(如催產(chǎn)素受體基因的 rs53576 GG型等)對樂觀具有獨特的作用。

4 總結與展望

綜上所述, 樂觀給個體帶來諸多好處是因為樂觀者具有正性偏向, 并主要體現(xiàn)在注意、知覺、記憶、解釋風格、應對策略的選擇、情緒、動機及期待方面。而這種偏向的神經(jīng)機制可能與前扣帶回喙部、前額葉皮質激活水平密切相關。盡管有關樂觀心理機制的研究已經(jīng)取得上述成果, 但是該領域仍存在不足之處, 未來研究需要注意以下三點：

首先, 未來研究應該著重考察樂觀核心認知結構——期待——本身的認知機制。樂觀從本質上來說是一種認知結構, 其核心是期待。借助期待結果的好壞, 這種維度也包含著情緒的意味(Carver & Scheier, 2014)。而當前樂觀的研究基本上是通過劃分不同樂觀程度的受試者來考察樂觀者和悲觀者在認知加工過程中的不同表現(xiàn), 進而探討樂觀的心理機制(Levens & Gotlib, 2012;Gibson & Sanbonmatsu, 2004), 較少對樂觀核心的認知結構——期待——本身進行深入考察。當然,這主要是因為我們在實驗室很難對特質樂觀進行嚴格的操縱。但是氣質性樂觀的概念卻給我們提供了一個新的研究思路, 即對個體的期待進行操縱。我們可以在實驗室條件下通過操控某些變量使被試產(chǎn)生一種積極或消極的期待, 然后考察不同期待對認知過程的影響, 從而揭示樂觀認知機制。Segerstrom (2011)曾提到在樂觀作為一種人格特質得到深入研究之前, 心理學家就曾經(jīng)通過操作期待來使人們變得更樂觀或更悲觀。如Carver,Blaney和Scheier (1979)通過指導語對期待進行操作, 發(fā)現(xiàn)誘發(fā)出積極期待的個體解決難題的時間顯著長于那些誘發(fā)出消極期待的個體。未來, 我們可以延長線索提示范式中的線索提示與預期刺激(正性或負性)之間的時間間隔, 并且在其中安排某些認知任務, 這樣便可通過不同情緒期待下被試完成認知任務的差異來考察積極期待對認知的影響, 進而深入探討樂觀的認知心理機制。

其次, 未來研究應該合理劃分樂觀和悲觀。已有的樂觀實驗研究大多單純以悲觀為基線考察樂觀的心理機制, 這可能不夠全面。Scheier和Carver (1985)提出氣質性樂觀時認為樂觀和悲觀是一個維度的兩端, 但是現(xiàn)有研究發(fā)現(xiàn)樂觀和悲觀這兩個維度之間僅呈低相關(Herzberg, Glaesmer,& Hoyer, 2006; 溫娟娟, 2012)。而且, 個體可以同時具有高樂觀和高悲觀這兩種特質傾向(Benyamini,2005; 陶沙, 2006)。這說明, 樂觀的反面可能是缺乏樂觀而并非悲觀(Marshall, Wortman, Kusulas,Hervig, & Vickers, 1992)。同理, 悲觀的反面也不是樂觀, 而是缺乏悲觀(Robinson-Whelen, Kim,MacCallum, & Kiecolt-Glaser, 1997)。缺乏樂觀與存在悲觀可能會造成不同的后果(Norem & Chang,2001)。所以, 這就意味我們不能僅依據(jù)LOT-R問卷總分簡單地將個體歸為樂觀者或悲觀者。未來,一方面, 我們可以依據(jù)樂觀LOT-R問卷兩個維度的得分高低劃分不同氣質性樂觀類型的個體來考察樂觀的心理機制。如有研究據(jù)此分類, 發(fā)現(xiàn)具有高樂觀低悲觀傾向的個體占總體的 35.9%; 同時具有高樂觀高悲觀傾向的個體占 19.8%; 不具有明顯樂觀悲觀傾向的個體占 21%; 具有低樂觀高悲觀傾向的個體占 23.4%, 并且上述 4種類型在壓力和抑郁量表上的得分具有顯著差異(陶沙,2006)。這說明, 不同氣質性樂觀類型的劃分是有必要的。另一方面, 在進行回歸預測分析時, 我們不僅以樂觀LOT-R的總分為預測變量, 還可以以各維度分數(shù)為預測變量。如有研究以樂觀維度和悲觀維度的分數(shù)為預測變量發(fā)現(xiàn), 悲觀維度而非樂觀維度的分數(shù)能夠顯著預測工作記憶中情緒信息的連接和打破能力(Levens & Gotlib, 2012)。

再次, 未來研究應該采取事件相關電位(ERP)技術考察樂觀發(fā)生作用的時間特征。樂觀發(fā)生的作用可能會隨著時間而變化。比如樂觀是對未來的積極期待, 但是當所期待的事件未能實現(xiàn)時,樂觀者會感到更多的失望或悲傷嗎？有研究發(fā)現(xiàn)面對落空的期待, 相對于消極期待者, 積極期待者感知到的負面情緒并沒有顯著增加(Brown &Marshall, 2001)。這有可能是因為期待落空之后,樂觀者能夠迅速地調整自己的情緒。不過因為這一結果是通過調查研究獲得的, 可能由于其所測量情緒的滯后性, 所以研究并未發(fā)現(xiàn)樂觀者與悲觀者所經(jīng)歷情緒的差異。而且到目前為止, 考察樂觀神經(jīng)生理機制的研究均是采用fMRI或EEG的方法(De Pascalis et al., 2013; Sharot et al., 2007),主要是從大腦空間上揭示了樂觀的神經(jīng)生理基礎,卻沒有采用高時間分辨率的事件相關電位技術(ERP)考察樂觀發(fā)生作用的時間特征。

總之, 未來研究應進一步考察樂觀的核心即期待的作用機制。這種期待既有情緒的意味也有動機的成分, 從而產(chǎn)生對未來及現(xiàn)在正在進行任務的影響。而這些是探究樂觀心理機制的核心。我們對基于此發(fā)展的樂觀人格特質的考察, 也可以不必拘泥于樂觀和悲觀的兩級劃分, 而將對未來的期待作為核心部分。另外, 神經(jīng)機制方面, 樂觀與涉及情緒與動機信息加工的腦結構如前扣帶回喙部、前額葉皮質的激活水平存在顯著相關。由此, 未來研究可以將期待?價值理論、人格理論與神經(jīng)基礎全面整合, 深入且全面考察樂觀的心理機制。

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