不禁, 赶忙, 亲眼, 特地, 特意: adverbs of manner
【六10】方式副词 / adverbs
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
These five adverbs go between the subject and the verb and say how the action is done. 不禁: one cannot help doing, an involuntary reaction (我不禁笑了). 赶忙: one hurries to do it at once, in a narrated past (他赶忙站了起来). 亲眼: with one's own eyes (亲眼看到; likewise 亲耳听到, 亲手做). 特地 and 特意: one does it specially, out of consideration or for a definite purpose (妈妈特意做了我爱吃的菜).
特地 and 特意 are nearly interchangeable. Keep them apart from 赶紧 (which also works for commands), 故意 (on purpose, often with ill will) and 亲自 (in person: 亲自去, go there yourself).
Register: mostly narration and careful writing, which is why they sit naturally in the retelling of a scene from a novel.
Examples
听到这个好消息，我不禁笑了起来。
Tīngdào zhège hǎo xiāoxi, wǒ bùjīn xiào le qǐlai.When I heard the good news, I couldn't help laughing.
妈妈知道我今天回家，特意做了我爱吃的菜。
Māma zhīdào wǒ jīntiān huí jiā, tèyì zuò le wǒ ài chī de cài.Mum knew I was coming home today and had specially cooked my favourite dishes.
你不用特地跑一趟，发个消息就行了。
Nǐ bú yòng tèdì pǎo yí tàng, fā ge xiāoxi jiù xíng le.You needn't make a special trip; a message will do.
看到客人来了，老师赶忙站起来迎接。
Kàndào kèrén lái le, lǎoshī gǎnmáng zhàn qǐlai yíngjiē.Seeing the guests arrive, the teacher hurried to his feet to welcome them.
这件事是我亲眼看见的，不会有错。
Zhè jiàn shì shì wǒ qīnyǎn kànjiàn de, bú huì yǒu cuò.I saw this with my own eyes, so there is no mistake.
看着那些老照片，他不禁红了眼睛。
Kànzhe nàxiē lǎo zhàopiàn, tā bùjīn hóng le yǎnjing.Looking at those old photos, he couldn't help his eyes turning red.
Common mistakes
✗ 你赶忙过来！ → ✓ 你赶紧过来！ (赶忙 only narrates what someone did, it cannot give an order).
✗ 他特意把我的杯子打碎了。 → ✓ 他故意把我的杯子打碎了。 (特意 is a considerate purpose, 故意 a deliberate and often hostile act).
✗ 我亲眼听到了他的声音。 → ✓ 我亲耳听到了他的声音。 (亲眼 goes with seeing, 亲耳 with hearing).