Domestic dogs (Canis familiaris) recognise meaningful content in monotonous streams of read speech

Domestic dogs (Canis familiaris) can recognize basic phonemic information from human speech and respond to commands. Commands are typically presented in isolation with exaggerated prosody known as dog-directed speech (DDS) register. Here, we investigate whether dogs can spontaneously identify meaningful phonemic content in a stream of putatively irrelevant speech spoken in monotonous prosody, without congruent prosodic cues. To test this ability, dogs were played recordings of their owners reading a meaningless text in which we inserted a short meaningful or meaningless phrase, either read with unchanged reading prosody or with an exaggerated DDS prosody. We measured the occurrence and duration of dogs’ gaze at their owners. We found that, while dogs were more likely to detect and respond to inserts that contained meaningful phrases spoken with DDS prosody, they were still able to detect these meaningful inserts spoken in a neutral reading prosody. Dogs detected and responded to meaningless control phrases in DDS as frequently as to meaningful content in neutral reading prosody, but less often than to meaningful content in DDS. This suggests that, while DDS prosody facilitates the detection of meaningful content in human speech by capturing dogs’ attention, dogs are nevertheless capable of spontaneously recognizing meaningful phonemic content within an unexaggerated stream of speech.

家犬（Canis familiaris）能够识别人类言语中的基础音位信息，并对指令做出响应。这类指令通常以孤立形式呈现，并伴随被称为面向犬类言语（dog-directed speech, DDS）的夸张韵律语调。本研究旨在探究家犬能否在无匹配韵律线索的情况下，自发识别以单调韵律呈现、看似无关的连续言语中的有意义音位内容。为验证该能力，我们向家犬播放其主人朗读无意义文本的录音，文本中嵌入了一段简短的有意义或无意义短语，这些短语要么以正常朗读韵律呈现，要么以夸张的面向犬类言语韵律呈现。我们记录了家犬注视主人的频次与持续时长。研究结果显示：尽管家犬对以面向犬类言语韵律呈现的有意义短语的检测与响应概率更高，但它们仍能识别以中性朗读韵律呈现的此类有意义嵌入短语。家犬对以面向犬类言语韵律呈现的无意义对照短语的检测与响应频次，与对中性朗读韵律下的有意义内容相当，但低于对面向犬类言语韵律下的有意义内容的响应频次。这表明，尽管面向犬类言语韵律通过吸引家犬的注意力，提升了其对人类言语中有意义内容的检测效率，但家犬依然能够自发识别非夸张韵律的连续言语中的有意义音位内容。